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Application ManualAboveNEMA Motors

Application Manual for AboveNEMA Motors

Siemens Industry, Inc.Drive Technologies Division

Large Drives4620 Forest AvenueNorwood, OH 45212

Telephone: (513) 841-3100Fax: (513) 841-3101

Visit us on the web at:USA.Siemens.com/motors

http://www.usa.siemens.com/motors


General Information

The information in this manual is company confidential and is for use by Siemens Industry, Inc.employees only.

Information in this manual is subject to change without notice.

NOTE: This manual supersedes all previous versions of the Application Manual for Above NEMAMotors ANAM-00001-0118.


Table of ContentsSection 1: Product Information .......................................................................................................... 5

Section 2: Electrical Information ..................................................................................................... 23

Section 3: Mechanical Information ................................................................................................. 35

Section 4: Accessories ...................................................................................................................... 95

Section 5: Standards ...................................................................................................................... 121

Section 6: Testing ........................................................................................................................... 154

Section 7: Special Applications and Formulae .............................................................................. 165


Product Information

Section 1Page 1Date Jan-18

Table of ContentsProduct Range and Scope .................................................................................................................. 2 Horizontal ODP/WPI/WPII/TEWAC – 4kV .............................................................................................. 2 Horizontal TEFC – 4kV ........................................................................................................................ 3 Horizontal TEAAC – 4kV ..................................................................................................................... 4 Horizontal ODP/WPI/WPII/TEWAC – 6.6kV ........................................................................................... 5 Horizontal TEFC – 6.6kV ..................................................................................................................... 6 Horizontal TEAAC – 6.6kV .................................................................................................................. 7 Vertical ODP/WPI/WPII – 4kV ............................................................................................................... 8 Vertical TEFC/TEAAC – 4kV ................................................................................................................. 9Siemens AboveNEMA Motor Features at a Glance ......................................................................... 10 4 Open Drip-Proof / Weather Protected Type I (CG Motors) .................................................................. 10 Weather Protected Type II (CGII Motors)........................................................................................... 11 Totally Enclosed Water-to-Air Cooled (CGG Motors) ......................................................................... 12 Totally Enclosed Fan Cooled (CZ / CGZ Motors) ................................................................................ 13 Totally Enclosed Air-to-Air Cooled (CAZ Motors) ............................................................................... 14 IEEE 841 Specified Motors (CZ / CGZ Motors) ................................................................................... 15

API 541 / API 547 Specified Motors .................................................................................................. 16Induction Motor Type Designations and Mechanical Features ...................................................... 17 4 Basic Type Modifications .................................................................................................................. 17 Frame Modifications ........................................................................................................................ 18


Product Information


Product Range and Scope

Horizontal ODP / WPI / WPII / TEWAC– 4kV

Open Drip Proof / Weather Protected Type I /Weather Protected Type II / Totally Enclosed Water-Air Cooled


Product Information



Horizontal TEFC – 4kV

Totally-Enclosed Fin Cooled


Product Information



Horizontal TEAAC – 4kV

Totally-Enclosed Air-Air Cooled


Product Information



Horizontal ODP / WPI / WPII / TEWAC – 6.6kV

Open Drip Proof / Weather Protected Type I /Weather Protected Type II / Totally Enclosed Water-Air Cooled


Product Information



Horizontal TEFC – 6.6kV

Totally-Enclosed Fin Cooled


Product Information



Horizontal TEAAC – 6.6kV

Totally-Enclosed Air-Air Cooled


Product Information



Vertical ODP/WPI/WPII – 4kV

Open Drip Proof / Weather Protected Type I / Weather Protected Type II


Product Information



Vertical TEFC / TEAAC – 4kV

Totally-Enclosed Fin Cooled / Totally-Enclosed Air-Air Cooled


Product Information


Siemens AboveNEMA Motor Features at a Glance

Open Drip-Proof / Weather Protected Type I (CG / 1RA Motors)


Product Information



Weather Protected Type II (CGII / 1RP / 1SP Motors)


Product Information



Totally Enclosed Water-to-Air Cooled (CGG / 1RN / 1SL Motors)


Product Information



Totally Enclosed Fan-Cooled (CZ / CGZ / CMZ / 1LA / 1NS Motors)


Product Information



Totally Enclosed Air-to-Air Cooled (CAZ / 1RQ / 1SG Motors)


Product Information



IEEE 841 Specified Motors (CZ / CGZ / CMZ / 1LA / 1NS Motors)


Product Information



API 547 / 541 Specified Motors


Product Information


Induction Motor Type Designations and Mechanical Features

Basic Type Modifications

CG - ODP, WPI 500, 580, 680, 800, 1120* Frames

CGII - WPII 500, 580, 680, 800, 1120*, SH630**, SH710** Frames

CGG - TEWAC 580, 680, 800, 1120*, SH630** & SH710** Frames

CZ or CGZ or CMZ - TEFC 500, 580, SH400**, SH450**, 880**, SH560** Frames

CAZ - TEAAC 580, 680, 800, 1120*, SH630**, SH710** Frames

1RA – ODP, WPI 500, 580, 680, 800 Frames

1RP – WPII 500, 580, 680, 800, SH630**, SH710** Frames

1SP – WPII (Div. 2) 500, 580, 680, 800, SH630**, SH710** Frames

1RN – TEWAC 580, 680, 800, 1120*, SH630** & SH710** Frames

1SL – TEWAC (Div. 2) 580, 680, 800, 1120*, SH630** & SH710** Frames

1RQ – TEAAC 580, 680, 800, 1120*, SH630** & SH710** Frames

1SG – TEAAC (Div. 2) 580, 680, 800, 1120*, SH630** & SH710** Frames

1LA – TEFC 500, 580, SH400**, SH450**, 880**, SH560** Frames

1NS – TEFC (Div. 2) 500, 580, SH400**, SH450**, 880**, SH560** Frames

* available only in vertical orientation**available only in horizontal orientation


Product Information


Induction Motor Type Designations and Mechanical Features

Frame Modifications

AO - Separate Fan Motor to blow air over the totally enclosed frame (TEAO)

B – External blower with a top enclosure

BB – Internal and external blowers with a top enclosure

D – Flanged. Indicates that motor is to be supplied with a D-flanged bearing housing onthe drive end.

F – Horizontal motor with flanged housing

HS – Vertically mounted hollow shaft

N – Motors with designation ‘N’ (ex. NCZ) represent non-standard frame sizes that areavailable upon special request. Consult factory for description of offerings.

P – Pipe-Ventilated Motor

S – Short shaft (only for 500/580 frames). Indicates motor is to be supplied withSiemens standard short shaft extension for direct connection except on 680 frameseries where no suffix is used.

V – Vertically mounted motor

Y – Special mounting. Non-NEMA BA dimension, but is Norwood standard.

YZ – Special mounting and special shaft extension

Z – Special shaft length, diameter or keyway. Indicates motor is to be supplied withnon-standard or special shaft dimensions.


Electrical Information

Section 2Page 1Date Dec-17

Table of ContentsInsulation Systems ............................................................................................................................. 2 Insulation System Reference .............................................................................................................. 2 Insulation System (600 volts and lower onlyl) .................................................................................... 2 MI-CLAD Insulation System (0-4,200 volts) ........................................................................................ 3 MICALASTIC Insulation System (0-7,200 volts) ................................................................................... 4 MICALASTIC Insulation System (0-15,000 volts) ................................................................................. 5External Load Wk2 Capabilities .......................................................................................................... 6External Connection Diagrams .......................................................................................................... 9 Three Phase – 9 Lead - Wye................................................................................................................ 9 Part Winding Start – Three Phase – 9 Lead - Wye ................................................................................ 9 Three Phase – 9 Lead - Delta ............................................................................................................ 10 Part Winding Start – Three Phase – 6 Lead - Wye .............................................................................. 10 6 Lead – Wye Delta Start .................................................................................................................. 11Temperature Rise Standards ........................................................................................................... 12




Insulation Systems

Insulation System Reference

Table 2.1. Corresponding Insulation Type to VoltageType/ Voltage 0-4200 Volts 4201-7200 Volts 7201-13800 Volts

MI-CLAD Yes1,2 No NoMedium Voltage

MicalasticYes1 Yes No

Micalastic3 Yes Yes Yes

1If coils require Mica wrapped strand insulation they will be built as Micalastic.2All API MI-CLAD stators will be built in house with a VPI epoxy-based resin.3All SH630 & SH710 motors will use the Micalastic Insulation SystemNote: SH560 can not have a MI-CLAD insulation system.

Insulation System (only 600 volts and lower)

This stator is insulated with a Class “F” insulation system. The conductor is Class “H” heavypolyester/amide-imide enamel insulated round copper wire and is wound as a group of coils(Each wire of a turn is one continuous piece of wire per group of coils).

A slot liner made of a polyester fiber/film laminate is placed in each slot. When the coilsbecome loose in the slots, they are tightened by using additional slot liner material. A centertrough made of polyester fiber/film laminate is placed between the top and bottom coils in theslot.

After the coils have been placed in the slots, a piece of acrylic varnished glass tubing isplaced on each lead. The phase groups are insulated on both ends with sheets of varnished glasscloth. The slot liner is folded over the coils and a polyester glass mat laminate top stick isinserted in the stick notches.

Jumper and neutral connections are made with compression type solderless connectorsand insulated with acrylic glass tubing. Jumpers, neutrals, leads and the end opposite leads aresecurely tied with polyester tie tape.

The completely wound stator is dipped two times in Class "H" hybrid epoxy insulatingresin and baked after each dip.




Insulation Systems

MI-CLAD Insulation System (0-4,200 volts)

The conductors are made of rectangular copper insulated with heavy polyester/amide-imide enamel or heavy polyester/amide-imide enamel plus varnished single Dacron glass. Insome cases, the conductors are insulated with reinforced Mica tape. Strands of the wound coilloop are bonded with a polyester resin during a hot pressing operation. The loop is then spreadand properly shaped.

The entire coil is taped with reinforced Mica tape. The number of layers of tape increasewith voltage levels. The entire coil is taped with a protective polyester armor tape. When coronaprotection is needed, conductive armor tape is used on the slot portion of the coil.

When corona protection is not required, the coils are placed in the stator slots withpolyester fiber combination slot liners. The slot liners are trimmed flush along with the bottomsof the slot stick notches. Top sticks, made from glass mat epoxy, are inserted in the sticknotches. The coils are lashed to coil supports with polyester tie tape and blocked with polyesterglass laminate and polyester felt. Coil-to-coil connections are insulated with acrylic glass tubingor with a combination of Mica tape and polyester armor tape. Lead connections are insulatedwith silicone rubber tape and polyester armor tape.

The completely wound and connected stator is vacuum pressure impregnated (VPI) witha 100% solid thermosetting resin. The VPI treatment subjects the entire stator assembly to a highvacuum, drawing out entrapped air and gases in the insulation system. The stator is thenflooded with the epoxy resin and the tank is pressurized to several times atmospheric pressure.The assembly is then baked to cure the catalyzed resin, producing a solid sealed insulationsystem impervious to moisture and chemical attack.




Insulation Systems

MICALASTIC Insulation System (0-7,200 volts)

The conductors are made of rectangular copper insulated with heavy polyester/amide-imide enamel or heavy polyester/amide-imide enamel plus varnished single Dacron glass. Insome cases, the conductors are insulated with reinforced Mica tape. Strands of the wound coilloop are bonded with a polyester resin during a hot pressing operation. The loop is then spreadand properly shaped.

The entire coil is reinforced with Mica tape. The number of layers of tape increase withvoltage levels. The entire coil is taped with a protective polyester armor tape. When coronaprotection is needed, conductive armor tape is used on the slot portion of the coil.

Top sticks are either made from epoxy glass laminate or magnetic wedges and areinserted in the stick notches.

The coils are lashed to coil supports with polyester tie tape and blocked with a glass mat.Coil-to-coil connections are insulated with silicone glass tubing or with Mica tape and polyesterarmor tape. Lead connections are insulated with silicone rubber tape and polyester armor tape.

The completely wound and connected stator is vacuum pressure impregnated with a100% solid thermosetting resin. The VPI treatment subjects the entire stator assembly to a highvacuum, drawing out entrapped air and gases in the insulation system. The stator is thenflooded with the epoxy resin and the tank is pressurized to several times atmospheric pressure.The assembly is then baked to cure the catalyzed resin, producing a solid sealed insulationsystem impervious to moisture and chemical attack.




Insulation Systems

MICALASTIC Insulation System (0-15,000 volts)

The conductors are made of rectangular copper, insulated with Mica tape. The turns ofthe wound coil loop are bonded with a resin during a hot pressing operation. The loop is thenspread and properly shaped.

The entire coil is taped with reinforced Mica tape. The number of layers of tape isincreased with the voltage. The end turns of the coil are taped with a protective polyester armortape. To provide corona protection, conductive armor tape is used on the slot portion of the coiland semi-conductive grading tape is applied at each end of the slot portion.

The coils are lashed to coil supports with polyester tie tape and blocked with a glass mat.Coil-to-coil connections are insulated with Mica tape and polyester armor tape. Lead connectionsare insulated with silicone rubber tape and polyester armor tape.

The completely wound and connected stator is vacuum pressure impregnated with a100% solid thermosetting resin. The VPI treatment subjects the entire stator assembly to a highvacuum, drawing out entrapped air and gases in the insulation system. The stator is thenflooded with the epoxy resin and the tank is pressurized to several times atmospheric pressure.The assembly is then baked to cure the catalyzed resin, producing a solid sealed insulationsystem impervious to moisture and chemical attack. The lead cable is insulated with siliconerubber.




External Load Wk2 Capabilities

NEMA MG1 – 2016, Table 20-1 lists load inertia which Siemens ANEMA induction motorshaving performance characteristics in accordance with NEMA standards can acceleratesuccessfully under the following conditions:

1. Applied voltage and frequency with variation in the voltage +/-10% of rated voltage with ratedfrequency or with variation in the frequency +/-5% of rated frequency with rated voltage.

2. During the accelerating period, the connected load torque should be equal to, or less than, atorque which varies as the square of the speed and is equal to rated torque at rated speed.

3. Two starts in secession (coasting to rest between starts) with the motor initially at ambienttemperature (cold start), or one start with the motor initially at temperature not exceeding itsrated operating temperature (hot start).

NOTE: Designs are available which can safety accelerate considerably more inertia withoutchanging frame size. For motors of 1000 HP and smaller, designs are available to acceleratetwice these values in same frame size. For higher horsepower or higher inertias than those listedin the chart, consult factory.





Table 2.2. External load capability of Siemens ANEMA Polyphase Squirrel-cage InductionMotors

NEMA MG1 – 2016 (Table 20-1)

HP

Synchronous Speed, Rpm3600 1800 1200 900 720 600 514 450 400

Load Wk2 (Exclusive of Motor Wk2), Lb-ft2

200 … … … … … 12060 17530 24220 32200250 … … … … 9530 14830 21560 29800 39640300 … … … 6540 11270 17550 25530 35300 46960350 … … … 7530 12980 20230 29430 40710 54200400 … … 4199 8500 14670 22870 33280 46050 61300450 … … 4666 9460 16320 25470 37090 51300 68300500 … … 5130 10400 17970 28050 40850 56600 75300600 443 2202 6030 12250 21190 33110 48260 66800 89100700 503 2514 6900 14060 24340 38080 55500 76900 102600800 560 2815 7760 15830 27440 42950 62700 86900 115900900 615 3108 8590 17560 30480 47740 69700 96700 129000

1000 668 3393 9410 19260 33470 52500 76600 106400 1419001250 790 4073 11380 23390 40740 64000 93600 130000 1736001500 902 4712 13260 27350 47750 75100 110000 153000 2045001750 1004 5310 15060 31170 54500 85900 126000 175400 2346002000 1096 5880 16780 34860 61100 96500 141600 197300 2641002250 1180 6420 18440 38430 67600 106800 156900 218700 2930002500 1256 6930 20030 41900 73800 116800 171800 239700 3213003000 1387 7860 23040 48520 85800 136200 200700 280500 3765003500 1491 8700 25850 54800 97300 154800 228600 319900 4298004000 1570 9460 28460 60700 108200 172600 255400 358000 4816004500 1627 10120 30890 66300 118700 189800 281400 395000 5320005000 1662 10720 33160 71700 128700 206400 306500 430800 5810005500 1677 11240 35280 76700 138300 222300 330800 465600 6280006000 ... 11690 37250 81500 147500 237800 354400 499500 6750007000 ... 12400 40770 90500 164900 267100 399500 565000 7640008000 ... 12870 43790 98500 181000 294500 442100 626000 8500009000 ... 13120 46330 105700 195800 320200 482300 685000 931000





Table 2.2. cont. External load capability of Siemens ANEMA Polyphase Squirrel-cageInduction Motors

NEMA MG1 – 2016 (Table 20-1)

HP

Synchronous Speed, Rpm3600 1800 1200 900 720 600 514 450 400

Load Wk2 (Exclusive of Motor Wk2), Lb-ft2

10000 ... 13170 48430 112200 209400 344200 520000 741000 1100900

11000 ... ... 50100 117900 220000 366700 556200 794000 1084000

12000 ... ... 51400 123000 233500 387700 590200 844800 1155000

13000 ... ... 52300 127500 244000 407400 622400 893100 1224000

14000 ... ... 52900 131300 253600 425800 652800 934200 1289000

15000 ... ... 53100 134500 262400 442900 681500 983100 1352000Note: for applications above 15,000HP consult factory




External Connection Diagrams

Single Speed

Three Phase – 9 Lead - Wye

Part Winding Start - Three Phase – 9 Lead - Wye

L1 L2 L3Low T1 T7 T2 T8 T3 T9 T4 T5 T6 YYHigh T1 T2 T3 T4 T7 - T5 T3 - T6 T9 Y

Volts Lines Connected Together Conn.

L1 L2 L3Run T1 T7 T2 T8 T3 T9 T4 T5 T6 YYStart T1 T2 T3 T4 T5 T6 Y

Lines Connected Together Conn.





Single Speed

Three Phase – 9 Lead - Delta

Part Winding Start - Three Phase – 6 Lead - Wye

L1 L2 L3Low T1 T6 T7 T2 T4 T8 T3 T5 T9 Δ ΔHigh T1 T2 T3 T4 T7 - T5 T3 - T6 T9 Δ

Volts Lines Connected Together Conn.

Lines L1 L2 L3Start T1 T2 T3 T2 T8 T9 OpenRun T1 T7 T2 T8 T3 T9





Single Speed

6 Lead - Wye Delta Start

L1 L2 L3Run T1 T2 T3 T4 T5 T6 YStart T1 T6 T2 T4 T3 T5 Δ

Lines Connected Together Conn.




Temperature Rise Standards

When operated at rated voltage and rated frequency, the observable temperature rise ofthe motor windings, above the temperature of the cooling air, shall not exceed the values in thefollowing table. Note that separate values are given for motors with a 1.0 service factor and 1.15service factor. The values in the table labeled "1.0 service factor" are for motors with 1.0 servicefactor when operated at rated load. Likewise, the values labeled "1.15 service factor" are formotors with a 1.15 service factor when operated at service factor load. These two parts of thetable apply individually to a particular motor rating (that is 1.0 or 1.15 service factor), and it isnot intended or implied that they may be applied as a dual rating to an individual motor.

Table 2.3. Max. Winding Temperature Rise vs Service Factor, Motor Rating, Voltage

Method ofTemperature

Determination

Motor Rating andVoltage

Maximum Winding Temperature Rise °C

1.0 Service Factor 1.15 Service Factor

Class B Class F Class H Class B Class F Class H

Resistance All 80 105 125 90 115 135

EmbeddedDetector

1500HP or Less 90 115 140 100 125 150

More than 1500HPa. 7000 Volts or less

85 110 135 95 120 145

b. more than 7000Volts

80 105 125 90 115 135

Note: Temperature rise in the table is based on a reference ambient temperature of 40°C.

Embedded detectors are located within the slot of the machine and usually are resistanceelements, but may be thermocouples. For motors equipped with embedded detectors, thismethod shall be used to demonstrate conformity with the standard.


Mechanical Information


Table of ContentsTerminal Boxes .................................................................................................................................. 3 Main Box Assignment ........................................................................................................................ 3 Main Box Material and Dimensions .................................................................................................... 3 Main Box Features and Options.......................................................................................................... 4 Main Box Drawings ............................................................................................................................ 5 Standard SH710 Frame Series Terminal Box (1XF5)............................................................................ 7Balance ............................................................................................................................................... 8Shaft Material .................................................................................................................................... 9 API 541 3rd, 4th, and 5th Editions ......................................................................................................... 9Bearings ........................................................................................................................................... 10 Bearing Selection ............................................................................................................................. 11 Horizontal Bearing Arrangements .................................................................................................... 12 Limiting Speeds ............................................................................................................................... 13Anti-friction Bearings....................................................................................................................... 14 Ball Bearings .................................................................................................................................... 15 Roller Bearings ................................................................................................................................. 16 Bearing Series .................................................................................................................................. 16 Bearing Types (Shields and Seals) .................................................................................................... 17 Angle of Contact .............................................................................................................................. 18 Radial Deep-Groove Ball Bearings ..................................................................................................... 18 Open Enclosure Bearings ................................................................................................................. 18 Double Shielded Bearings ................................................................................................................ 19 Cylindrical Roller Bearings ................................................................................................................ 20 Bearing Quality and Life ................................................................................................................... 21 Cages and Corresponding Materials ................................................................................................. 22 Bearing Standards ............................................................................................................................ 23 ABMA Nomenclature – Ball Bearings ................................................................................................ 24 ABMA Nomenclature – Roller Bearings ............................................................................................. 25Sleeve Bearings ............................................................................................................................... 27 Babbitt Material ............................................................................................................................... 27 Bearing Clearance ............................................................................................................................ 27 Journal and Bearing Finish ............................................................................................................... 28 Alignment / Coupling of Flexibly Coupled Sleeve Bearing Motors ..................................................... 28 Motor End Play and Limited End Float of Couplings .......................................................................... 28 Setting of End Play ........................................................................................................................... 29 Self-Centering Couplings with Semi-Restricted End Play ................................................................... 30 Unrestricted or Free Floating Couplings ........................................................................................... 30 Mechanical Center Adjustment ........................................................................................................ 31




Table of ContentsLubrication ....................................................................................................................................... 32 Terminology .................................................................................................................................... 32Lubrication – Anti-friction Bearings ................................................................................................ 33 Grease ............................................................................................................................................. 33 Grease Types ................................................................................................................................... 34 Lubrication Frequency ..................................................................................................................... 35 Pure Oil Mist .................................................................................................................................... 37Lubrication – Sleeve Bearings ......................................................................................................... 38 Oils .................................................................................................................................................. 38 Oil Mist Purge .................................................................................................................................. 42 Cleanliness ...................................................................................................................................... 42 Flood Lube Requirements and Heat Rejection Rates ......................................................................... 43V-Belt Applications .......................................................................................................................... 44 Sheave Location .............................................................................................................................. 45 Max. Belt Pull Limits ......................................................................................................................... 45Standard Paint Process – Norwood Plant ........................................................................................ 49 Prime Coat ....................................................................................................................................... 49 Stator Assemblies ............................................................................................................................ 49 Oil Reservoirs ................................................................................................................................... 49 Rotors .............................................................................................................................................. 50 Finish Coat ....................................................................................................................................... 50 Special Paint Process ........................................................................................................................ 50Motor Rotation ................................................................................................................................. 51Sound Pressure Levels ..................................................................................................................... 52 Noise Requirements ......................................................................................................................... 52Mechanical Modifications for Low Temperature Motors ............................................................... 53Vibration and Critical Speeds .......................................................................................................... 54 Causes of Vibration .......................................................................................................................... 54 Vibration Measurement ................................................................................................................... 54 Vibration Limits ............................................................................................................................... 55 NEMA Limits .................................................................................................................................... 55 API Limits ......................................................................................................................................... 56 Practices Employed to Achieve Low Vibration .................................................................................. 56 Critical Speeds and Damped Rotor Resonance .................................................................................. 57




Terminal Boxes

Table 3.1a: Main Box AssignmentHP 460V or 575V <= 2300 V <= 4160 V <= 6900 V >6900 V

<=700 CI2 CI2 CI2 CI3 FS4701 – 1000 CI3 CI2 CI2 CI3 FS4

1001 – 1750 - CI2 CI3 CI3 FS41751 – 3000 - CI2 CI3 FS3 FS43001 – 5000 - CI3 FS1.5 FS3 FS45001 - 7000 - - FS2 FS3 FS4

*For High Voltage applications (>6900V), with components, use FS6.*Cast iron terminal boxes are not used on the SH630 & SH710 frames.

Table 3.1b: Main Box Material & DimensionsBox

NameMaterial Drop–AF

(in)Depth-

XD(in)

Height-XL (in)

Width-XW (in)

InternalVolume

(in3)

Approx.Weight

(lbs)CI2 Cast Iron 16 12.7 21.6 13 2620 81CI3 Cast Iron 18 15 27.9 21 6370 262

FS1.5 FabricatedSteel

- 20 28.5 24.4 13900 280

FS2 FabricatedSteel

- 22 31 37 25234 440

FS3 FabricatedSteel

- 36 43 37 57276 820

FS4 FabricatedSteel

- 27 52 49 68120 720

FS6 FabricatedSteel

- 50 78 42 163800 1780




Terminal Boxes

Table 3.1c: Main Box Features and OptionsFeature / Option FS1.5 FS2 FS3 FS4 FS6

NEMA 4X compliantNeoprene gasketBlowout panelDrain hole with plugRemovable neutral link2) N/ARemovable bottom plate (undrilled- to be drilled byothers for cable entry)Standoff insulators OANSI Type II N/A N/ALightning Arresters N/A N/A O N/A OSurge Capacitors N/A N/A O N/A OCurrent Transformers3) N/A O O N/A OMetering Current Tranformer7,8) O O O N/A OIris Partial Discharge N/A N/A N/A N/A OSpace Heater O O O O OTop or Bottom Entry O O O O N/ADrain hole with breather O O O O O

= Standard feature N/A = not available O = Optional feature (for additional price)

Table notes:1) The weights listed only include the weights of the main boxes and standard

equipment/accessories.2) The removable neutral link is supplied with 6 leads and a Wye connection.3) The current transformers are for differential protection (either Zone or Self-balancing

protection).4) All fabricated main boxes are a minimum of 0.18 inches sheet metal.5) FS2, FS3, FS4 and FS6 main boxes will be free-standing with feet and will require

support from beneath (supplied by others).6) FS2, FS3, FS4 and FS6 main box feet may not be on the same plane as the motor

mounting feet.7) Metering current transformer and current transformers not available together in FS2

box.8) Metering current transformer and standoff insulators are not available together in

FS1.5 box.9) FS4 & FS6 terminal boxes are available for High Voltage applications over 6900 volts.10) FS6 Box is only bottom entry by means of removable bottom plate.




Terminal BoxesMain Box Drawings

FS6 (High Voltage)

FS4 (High Voltage)




Terminal BoxesMain Box Drawings

FS3 FS2

20.0

26.9

18.0

15.0

FS1.5 CI313.0 12.7

21.6

16.0

CI2=> 5” NPT cable connection for Cast Iron boxes (CI2 & CI3)=> Removable bottom plate (undrilled) for the Fabricated Steel boxes (FS1.5, FS2, FS3,FS4 & FS6)

24.4 21.0

27.9




Terminal Boxes

Standard SH710 Frame Series Terminal Box (1XF5)

SH710 frame motors are equipped with a special terminal box due to the largervoltage and equipment size requirements. The standard terminal box for SH710 framemotors is a type 1XF5.

Table 3.2. SH710 Main Box Features and OptionsFeature / Option Box type 1FX5NEMA 4x compliant StdNeoprene gasket StdBlowout Panel StdDrain hole with plug StdRemovable bottom plate (undrilled – to bedrilled by others for cable entry)

Std

Standoff insulators StdANSI Type II StdLightning arrestors OptionalSurge capacitors OptionalCurrent transformers OptionalMetering current transformer1 OptionalSpace heater OptionalTop entry N/ADrain hole with breather OptionalIris® Partial Discharge measurement Optional

1) Metering current transformer and current transformers not available together

45.2

65.4




Balance

The easiest vibration to trace and reduce to a minimum is caused by anunbalanced rotor. It has large influence on the vibration of the yoke and bearing housing.

The rotors of all motors are dynamically balanced in high-speed precisionbalancing machines at the Norwood Plant.

If a low vibration limit on the application requires more precise balance; specialcare must be taken during rotor manufacturing. A low level of balance cannot beobtained in the presence of mechanical looseness, misalignment, bent shafts or rotor runout. These must be prevented by very close control of tolerances, fits, machining andfinishes before a low level of balance is attempted. Theoretically, rotor balancing willreduce only the vibration whose frequency is equal to rotational frequency. However, alow level of balance attenuates the possibility of other parts being excited to vibrate inresonance at their natural frequency.




Shaft Material

The standard shaft material is medium carbon steel, AISI 1045 steel, for mostmotors. A higher strength shaft (AISI 4140 or AISI 4340) will be supplied on motorswhere the design creates a need for more rigidity. When proximity probes or provisionsfor proximity probes are specified, special shaft material must be used to provide thenecessary magnetic properties for the probes. Medium carbon chromium molybdenumalloy steel, AISI 4140 containing 0.4% carbon, will be used for all shafts with or withoutwelded spider arms. All shaft materials are fine grained and are hot rolled into round barsof special quality and straightness. All 3600 RPM motor shafts are built without weldedspider arms. All 5812 frame, 680 frame, and 800 frame motors, 1800 RPM and slower,have spider arms welded onto the shaft.

Motors built to API 541 standards have the following special requirements:

API 541 3rd Edition, April 1995-For all 3600-RPM motors and all flexible shaft motors, the shaft shall be forged.- If specified by customer, the forging shall be ultra-sonic inspected before the

rotating element is assembled.- For all motors operating at 1800 RPM or slower and all motors operating below the

first lateral critical speed, a hot rolled shaft will be used.

API 541 4th Edition-Welded shaft or bar shaft/spider construction is not permitted on all 2 pole motors-For all welded shafts on 4 pole and slower machines, magnetic particle inspection is

required.-Heat-treated forged steel shafts shall be used for machines having any of the

following characteristics:- Finished shaft diameter 8 in. and larger- 2 Pole machines 1000hp and larger- Operation above the first lateral critical speed- Driving reciprocating loads- Using tapered hydraulic fit couplings

API 541 5th Edition-shaft forgings are required on ALL 2 pole motors




Bearings

Bearings are of major importance in the electric motor industry when talking aboutthe costs of operation and maintenance. Regardless of how reliable a motor may be,when a bearing fails it results in motor shutdown, costly repairs and loss of valuableproduction time.

There are two principal groups of bearings used in the electric motor industry today:

(1) anti-friction bearings(2) cylindrical sleeve bearings

The vast majority of general purpose motors are equipped with anti-friction bearings.Anti-friction bearings are designed to support and locate the rotating shaft in motors.They transfer loads between rotating and stationary members and permit relatively freerotation with minor friction. They consist of rolling elements (balls or rollers) between anouter and inner ring, which are evenly spaced from one another by cages or separators ofsome form.

Sleeve bearings are designed to create a load carrying film of fluid between the shaftand bearing. Sleeve bearings are designed to have approximately 0.002-inches per inchof shaft diameter clearance.

The primary function of the clearance is to provide a wedge shaped area that the oilfilm utilizes to create hydrodynamic pressure. This pressure is sufficient to carry therotating assembly weight applied to the bearing. Please see Figure 4.1 below:

Figure 3.1. Diagram showing shaft and bearing interaction for sleeve bearings




Bearings

Bearing Selection

Use the tables below and its corresponding explanations to help guide you inselecting bearings.

Table 3.3. Comparison of Anti-friction and Sleeve Bearings

Item 1: The life of anti-friction bearings is rated in L10 life (see Bearing Quality and Lifesection). They have a predicted finite life based on multiple factors. Sleeve bearings havean indefinite life, as the shaft rides on an oil film so there is no mechanical part wear.Item 2: Anti-friction bearings are widely used and standardized to a very fine degree,making it easy to obtain replacement bearings.Item 3: The ease of maintenance of anti-friction bearing motors is greater than sleevebearing motors. Sleeve bearings must be inspected more often. Housekeeping is less of aproblem with anti-friction bearings because there is no possibility of oil leakage. Anti-friction bearing replacement can be quickly and easily accomplished, as no fitting ofbearings is required.Item 4: The higher noise level of anti-friction bearings is sometimes critical in airconditioning applications.Item 5: Motors having anti-friction bearings may be mounted on a wall, tilted, or placedin a vertical position. Sleeve bearings will not operate in any of these positions.Item 6: Continuous thrust loads cannot be carried by sleeve bearings.Item 7: Heavy belt drives interfere with the formation of the oil wedge on which theoperation of sleeve bearings depends.Item 8: Wear of a sleeve bearing may be measured by noting changes in air gap. The rateof wear is slow, giving ample warning time. Anti-friction bearings fail quite rapidly afterunusual noise develops.Item 9: Anti-friction bearings do not require large oil reservoirs.

Item No. Factor Anti-Friction Sleeve

1 Long Life2 Availability3 Maintenance Ease4 Quietness5 Flexibility in Application6 Thrust Loads7 Heavy Belt Drives8 Prior Indication of Failure Due to Wear

9 Compactness




Bearings

Horizontal Bearing Arrangements

Table 3.4. Horizontal Bearing Arrangements

*All ball bearing machines are grease lubricated.*All sleeve bearing machines are ring oil lubricated2). Some machines require floodlubrication*See Flood Lube Requirements and Heat Rejection Rates.1) Ball Bearings not available for 8012 4 Pole2) SH710 2 Pole uses lobed bearings which do not contain oil rings. Redundantlubrication provisions may be necessary.

Frame Ball BearingsRoller

BearingsSleeve

Bearings

449 CZ – 2 Pole Standard Optional N/A449 CZ – 4 Pole & Slower Standard Optional N/A500 CG/CGII – All Speeds Standard Optional Optional

500 CZ – All Speeds Standard Optional Optional580 CG/CGII – All Speeds Standard Optional Optional

580 CZ – All Speeds Standard Optional OptionalSH400 CGZ – 2 Pole Standard N/A OptionalSH400 – 4 Pole & Slower Standard N/A Optional

680 CG/CGII/CAZ – 2 Pole N/A N/A Standard680 CG/CGZ/CAZ – 4 Pole & Slower Optional N/A StandardSH450 CGZ – 2 Pole N/A N/A Standard

SH450 CGZ – 4 Pole & Slower Standard N/A Optional800 CG/CGII/CAZ – 2 Pole N/A N/A Standard800 CG/CGII/CAZ – 4 Pole & Slower Optional1) N/A Standard

880 CGZ – 2 Pole N/A N/A Standard880 CGZ – 4 Pole & Slower Standard N/A OptionalSH560 1LA4 – 2 Pole N/A N/A Standard

SH560 1LA4 – 4 Pole & SlowerStandard Axial Standard

RadialOptional

800 CG/CGII/CAZ- 2Pole N/A N/A Standard

SH630 CG/CGII/CAZ – 2 & 4 Pole N/A N/A StandardSH630 CG/CGII/CAZ – 6 Pole & Slower Standard N/A OptionalSH710 CG/CGII/CAZ – 2 & 4 Pole N/A N/A Standard2)

SH710 CG/CGII/CAZ – 6 Pole & Slower Standard N/A Optional




Bearings

Limiting Speeds

The maximum speed at which a particular bearing can be operated is determinedby many factors. Factors typically included are bearing size and type, method oflubrication, operating load and temperature, bearing design and tolerances, speed, cagetype and material and required bearing life.

The bearing manufacturers publish limiting speed tabulations; however, becausethere are so many variables, the tabulations are typically only a set of guidelines. As thebearing size increases for a constant motor speed, the ball must travel a greater distance(measured in feet per minute) per revolution.

The increased speed under constant loading causes an increase in heating andmetal fatigue, resulting in a reduction in bearing life. In addition, higher peripheralspeeds make effective lubrication more difficult.




Anti-friction Bearings

Bearings are a minor item in relation to the manufacturing cost of an electricmotor, but when viewing the motor from a standpoint of economy of operation and costof maintenance, the bearing becomes an item of major importance. Regardless of howreliable a motor may be, bearing failure will not only cause motor shutdown, but alsoresult in costly repairs and loss of valuable production time. The vast majority of general-purpose motors are equipped with anti-friction bearings.

There are four main types of anti-friction bearings in use at Norwood Plant;

(1) Radial deep groove ball bearings(2) Cylindrical roller bearings(3) Angular contact ball bearings(4) Spherical roller thrust bearings

Every anti-friction bearing consists of four basic parts:

(1) The outer ring or outer raceway – mounts in the bearing chamber or housing.(2) An inner ring raceway – mounts on the motor shaft(3) The balls – space the inner and outer rings.(4) The cage, retainer or separator – evenly spaces the balls.

Bearings are designed to carry specific type loads. For example, some bearings aredesigned to carry loads in only one direction while others can carry loads in twodirections.

Thrust (axial) loads are defined as forces acting parallel with the motor shaft(Figure 3.2). Radial loads are defined as forces acting perpendicular to the motor shaft.

Figure 3.2. Two types of loads carried on motor shafts





Most bearing manufactures use a numerical designation to indicate bearing size.The last two digits of the basic bearing number indicate the bearing bore size, while thefirst one or two digits indicate the bearing series. For example, in a 207 size bearing, the07 represents the bore size, while the 2 shows the bearing is a light or 200 seriesbearing. Additional identification is used as a prefix or suffix to the basic bearing size toindicate a specific type of bearing. Bearing nomenclature also indicates accessories,which may be mounted directly on the bearing such as shields, seals, etc.

Ball Bearings

In a ball bearing, the race is curved in both an axial direction and a circumferentialdirection. Since the ball and race are elastic materials the contact between one anotherbecomes an elliptical area (See Figure 3.3).

Looking at the ball-race cross section (See Figure 3.4) it is apparent that differentball radii are in contact with the race and only true rolling can occur at one radius (R2),hence there must be sliding at the other radii.

There is sliding in areas A and B (See Figure 3.3), but occurs in oppositedirections of one another. Rolling also occurs along the two lines that separate areas Aand B, but must balance each other.

This sliding friction shows the need for good lubrication in these areas since thearea is very small and the unit load is very high. This constant stress vs. relief causesheating due to internal metal friction, which reiterates the need for lubrication.

Figure 3.3 Figure 3.4





Roller Bearings

In a cylindrical roller the radius of the roller is constant; hence, true rolling existsalong the contact line. Since the parts are elastic, an area of contact exists as shownbelow in Figure 3.5.

Figure 3.5. Basic Design of a Standard Roller Bearing

Very high unit loads exist since the width is small; however, the area of contact atany particular moment is considerably greater than that of a ball against raceway in a ballbearing. For this reason, the roller bearing can carry considerably greater radial loadsthan the equivalent size ball bearing.

Bearing Series

There are three common series of ball bearings: light or 200 series, medium or300 series, and heavy or 400 series. For a given size (205, 305,405) the bore is the same,but the diameter of the outer race is progressively larger, meaning the balls areprogressively larger in diameter. The nomenclature light, medium and heavy come fromthe direct correlation between the size of the ball and the load-carrying capacity.





Bearing Types (Shields and Seals)

Many bearings can be supplied with accessories such as shields or seals. A bearingshield consists of a pressed steel plate mounted, by crimping, on the outer ring. A radialclearance is maintained between the shield and the inner rotating ring of the bearing.This clearance is sufficient to allow passage of lubricant into the ball of the bearing itself;however, is sufficiently small enough to prohibit the entrance of foreign particles. Inmany cases, shields are used on both sides of the bearing. Figure 3.6 shows a typicalbearing with a singular shield.

Many types of bearing seals are available. The most commonly used type consistsof a neoprene or synthetic material bonded to a pressed steel plate. The pressed steelplate is used as a means of support for the synthetic material. The seal is crimped in theouter ring of the bearing and rubs on a polished surface of the inner ring of the bearing.Figure 3.7 depicts a typical bearing with a singular rubbing seal mounted in place.

Since seals have direct contact with the inner ring, they are highly efficient inpreventing entrance of foreign matter and retaining bearing lubricant. Because the sealactually rubs on the bearing inner ring, there is a slightly greater “torque drag” thanexperienced with a shielded bearing of the same size. The rubbing action also generatesheat; therefore, seals are not used on large bearings having high peripheral speeds orbearings having operating temperatures exceeding the seal material temperaturecapabilities. Other types of seals are available; however, in they are considerably widerand therefore require an increase in bearing width.

Figure 3.6. Single Shielded Conrad Bearings Figure 3.7. Single Sealed Conrad Bearing





Angle of Contact

The term “angle of contact” refers to the angle at which the ball contacts the innerand outer rings. In essence, this is the angle at which the effective force is transmitted.This angle of contact varies with different types of bearings from 0 to 40 degrees. Thehigher the angle of contact allows the bearing to better carry axial loading.

Radial Deep-Groove Ball Bearings

The most generally used type of anti-friction bearing is the radial deep-groove ballbearing. This bearing is designed to carry radial loads and moderate thrust loads in eitherdirection, simultaneous with, or independent of, radial load.

Open Enclosure Bearings

Open enclosure bearings consist of an inner and outer race, the ball retainer ring,and balls (Figure 3.8 below). This bearing can be re-lubricated without disassembling themotor; however, the open construction affords slight protection against over greasing.There is no protection against foreign elements that may be in the grease or in theatmosphere when the motor is dismantled.

Figure 3.8. Single-row, open enclosure deep-groove ball bearing.

Another disadvantage of the open construction is the churning of the greasesupply in the reservoir caused by rotation of the balls and retainer ring. The rotation ofthe ring churns the grease and will increase grease oxidation. Dust particles, which mayenter along the shaft, will mix with the grease and come in contact with the bearing.





Double Shielded Bearings

Double-shielded bearings are simply open-type bearings with a shield rolled intothe outer raceway on each side (Figure 3.9). The shield has a close running clearancewith the inner race. This clearance is sufficient to permit passage of grease, but is smallenough to protect the balls and raceways from large dirt particles that may enter thegrease during assembly or maintenance. This bearing is also pre-lubricated, but can bere-lubricated while in service.

Figure 3.9. Single row, double-shielded ball bearing

The double shield does not completely eliminate the possibility of over greasing,but it definitely minimizes it. These shields also serve to keep grease in the ball pathwhen the motor is mounted vertically by effectively preventing slumping of the greasesupply, resulting in increased grease life.The double-shielded bearing gives users the desirable features of both the open anddouble sealed bearings, while also eliminating most of the respective disadvantages. SeeTable 3.5 below for a comparison of bearing features.

Table 3.5. Comparison of Radial Deep-Groove Bearing Features

Features Open Sealed ShieldedBearing protected fromforeign material when

removed fromits housing enclosure

NO Yes Yes

Lubrication in service Yes NO Yes

Protection against vaporcontamination

Yes Yes Yes

Relative bearing cost Lower Higher Intermediate





Cylindrical Roller Bearings

When the radial load imposed on the bearing is in excess of the capacity of a ballbearing, which may occur when the load is belt driven, the cylindrical roller bearing isused. A 222 cylindrical roller bearing is capable of carrying 186% more radial load thanthe same size (6222) ball bearing.

Physically, this bearing is interchangeable with the ball bearing in any given size,but it does have operating limitations. The range of operating speeds for roller bearings ismuch less than the ball type because of noise and friction heat. The roller bearings can’tcarry axial loads and are usually used on the drive end only with a deep groove ballbearing on the non-drive end to control rotor float. Axial movement of the outer racewayof the roller bearing must be limited to keep it from disengaging from the inner race(Figure 3.10 and Figure 3.11).

Figure 3.10. Cylindrical Roller Bearing Type N Figure 3.10. Cylindrical Roller Bearing Type NU





Bearing Quality and Life

Electric Motor Quality (EMQ) is a term used to designate ball bearings producedfor electric motors where low noise and vibration are the most important. It is generallyrecognized that bearings in electric motors are made exclusively from vacuum-degassedsteel of the highest quality and close tolerances are maintained in the manufacturing ofthe balls and races. All ball bearings supplied by Siemens are EMQ.

The life, which 90% of a group of bearings will exceed, is known as the minimumL10 life. Bearings selected for Siemens motors will have an L10 life, which depends uponthe method of connection to the load. Direct connected motors will have a minimumdesign L10 life of 100,000 hours in continuous service. The bearing life of motorsconnected by belt drives is determined by the characteristics of the belt drive, includingthe pitch diameter of the sheaves, number and type of belts, and center-to-centerdistance. If the recommended belt drive limitations are followed and the drive is properlyaligned and lubricated, the minimum design L10 life will be two years in continuousservice.

When a group of identical bearings are run under set conditions of speed and loadthere will be a considerable variation in the fatigue lives. The exact cause of thisdispersion is not known. Since all bearings do not fail at the same time, it is necessary totreat the problem statistically. The life, which 50% of a group of bearings will exceed, isthe median life, sometimes known as L50 life. The median life is approximately five timesthe L10 life.





Cages and Corresponding Materials

Cages, also referred to as separators or retainers, serve the purpose ofmaintaining uniform rolling element spacing in the inner and outer rings of the bearingsas the rolling elements pass in and out of load zones. There are various cage-typematerials and configurations needed to meet specified service requirements. Thefollowing material is for informational purposes only. Please note: Refer any and allspecified cage material requests to Norwood before committing to any requests. Siemensstandard cage material for all bearings is pressed steel or machined brass. However, theanti-friction bearings for 680 and 800 frames contain machine brass cages as standard.

Steel cages are standard for many ball bearings. These cages haverelatively high strength and low weight. Steel cages can be used up to anoperating temperature of 300ºF and are not affected by lubricants or solutionsthat clean bearings. The standard for small and medium sized bearings is pressedsteel.

Brass cages are generally utilized in bearings where the application wouldsubject the bearing to heavily loaded conditions. Brass cages come in a machinedbrass configuration.





Bearing Standards

The Anti-friction Bearing Manufacturer’s Association, a non-profit bearingstandards group consisting of most bearing manufacturers, has established standards fortolerance, size and type of bearings. Most ball bearings are ordinarily supplied withstandard internal clearances between balls and raceways, commonly called bearing fitup.

Part of this original built-in internal clearance disappears after the bearing hasbeen mounted, because the inner ring is expanded when pressed on the shaft; leavingthe correct clearance for smooth operation in service.

The numerical amount of internal clearance is a variable dependent upon thephysical size and type of the bearing itself. Special internal clearances may be requiredfor special applications.

Fit up is extremely important and can vary from tight assembly where the ballsare under compression to looseness between the balls and races. It is usually detected byradial play in the bearing in a radial direction and by end shake in the direction parallel tothe bore. Fit up has no relation to quality, and different fit up can be obtained in allquality bearings. Siemens uses a standard bearing fit up, AFBMA-3.

In addition to the Anti-friction Bearing Manufacturers Association (AFBMA)standards, the Annular Bearing Engineers Committee (ABEC) has established qualitystandards to give standardization to tolerance. The ABEC numbers, designating standard,specially selected, super precision and ultra-super precision bearings are ABEC 1, 3, 5 and7, respectively. Standard motors use ABEC 1 quality bearings. Higher quality bearings areused in special motors where closer shaft run outs or low noise and vibration levels arerequired.

AFBMA recently established a standard nomenclature system. Although thissystem is not widely used, it does provide a standard means of identifying bearings.Siemens Norwood uses the AFBMA nomenclature for identifying bearings.





ABMA Nomenclature – Ball Bearings

“L” Designates a letter“D” Designates a number

*The letters for columns 2, 3, and 4 of modifications are omitted if none are applicable. Ifcolumn 4 is applicable, but not 3 or 2, X is put as a placeholder. Ex: 35BT03MXD03

Example:35BC02JPP0 - Standard deep groove, light series, standard steel cage, double shielded,standard fitup and standard tolerances MRC 207-SFF

Fitup & Tolerance

R - Low temperature silicone grease 100°FH - High temperature grease 275°FS - High temperature silicone grease 300°F

0 - Standard Tolerances - ABEC 13 - More precision than 0 - ABEC 35 - More precision than 3 - ABEC 5

0 - Standard fitup - AFBMA 0 or C/03 - Loose internal fitup - AFBMA 3 or C/34 Looser than C/3 - AFBMA 4 or C/4

G - Snap ring and groove in outer raceD - Single bearing modified for duplex mounting (DB, DF, or DT)

P - Single shielded - permanently fastenedPP - Double shielded - permanently fastenedR - Pair of bearings modified for duplex mounting - back to back (DB)T - Pair of bearings modified for duplex mounting - in tandem (DT)U - Pair of bearings modified for duplex mounting - face to face (DF)X - None of the above - see footnoteXX - None of the above - see footnote

J - Standard - Steel, sheet or strip form, centered by the ballsM - Bronze or brass, not sheet or strip, centered on the balls

10 - Extra light, e.g., 6000 (SKF)02 - Light e.g., 6200 (SKF)03 - Medium, e.g., 6300 (SKF)

BC - Standard deep groove ball bearing, e.g., 6308 (SKF)BT - Angular contact thrust bearing. E.g., 7313P (SKF)

e.g., 20 = 04, 75 = 15. 110 = 22. i.e., the last two digits of the bearing number are multiplied by 5 to obtain the bore

Inte

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Cle

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Col

umn

2or

3us

edfo

rR,T

orU

Type

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ball

reta

iner

Bearing TypeLL

Dim

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ries

Type

ofba

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DDDimension Series

Bear

ing

bore

inm

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L*Modifications

D** D**L LL*

Lubr

ican

t

Tole

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Bearing BoreDDD L**

Lubricant





ABMA Nomenclature – Roller Bearings

“L” Designates a letter“D” Designates a number

Example:130RU22M30 – Cylindrical roller bearing, self-aligning, brass/bronze cage, internalclearance less than normal, ABEC 1

Fitup & Tolerance

0 - Standard Tolerances - ABEC 13 - More precision than 0 - ABEC 35 - More precision than 3 - ABEC 5

0 - Normal internal clearance3 - Internal clearance less than normal4 - Internal clearances greater than normal

Not Applicable - This column is omitted

X - Any type of cageM - Brass or bronze, not in sheet or strip form, centered by tolling element

02 - Light series, e.g., N208 (SKF)03 - Medium series, e.g., N308 (SKF)22 - Series used for self-aligning spherical roller bearings, e.g., 22222 (SKF)23 - Series used for self-aligning spherical roller bearings, e.g., 22322 (SKF)94 - Series used for spherical roller bearings, e.g., 29420

RU - Cylindrical roller bearing, shoulders on outer ringTS - Spherical roller thrust beaing e.g., 29430 (SKF)

e.g., 20 = 04, 75 = 15. 110 = 22. i.e., the last two digits of the bearing number are multiplied by 5 to obtain the bore

Type

ofca

geor

ball

reta

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Dim

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Type

ofba

llbe

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Bea

ring

bore

inm

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Inte

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Dimension Series ModificationsDDD LL DD L L D

Bearing Bore Bearing Type





ABMA NomenclatureTable 3.6. ABMA Nomenclature for Norwood’s product line

Frame

Short Shaft Long Shaft

RPM NDE DE NDE

DirectConnected

DE Belted DE

449 TEFC3600-1200

80BC02J3 90BC03J3 80BC02J3 90BC03J3 90RU03M00

S449 TEFC 3600-1200


500 Open 3600 75BC02J3 75BC03J3 - - -

500 Open 1800 &Slower


500 TEFC 1800 &Slower


580 All 3600 75BC03J3 75BC03J3 - - -

580 Open1800 &Slower


580 TEFC1800 &Slower


6801800 &Slower

160BC02M3 160BC02M3 - - -

SH400 CGZ1800 &Slower

120BC02J3 120BC02J3 - - -

SH450 CGZ1800 &

900140BC02J3 140BC02J3 - - -

SH450 CGZ 1200 140BC02J3 150BC02J3 - - -

880 1800 &Slower

140BC03J3 140BC03J3 - - -

SH560 1LA4 1800 &Slower

170RU10M30& 170BC00J3

160RU10M30 - - -

SH630/2WPII/TEWAC

1200 &Slower

180RU10M &240BC10M30

240RU22M3 - - -

SH634/6WPII/TEWAC

1200 &Slower 190RU10M3

240RU22M3 &240BC10M30

- - -

SH630TEAAC

1200 &Slower 170RU10M3

220RU22M30 &220BC10M30

- - -

SH7101500

240RU22M30240RU22M30 &

240BC03M3- - -

SH7101200 &Slower

260RU22M30260RU22M30 &

260BC03M3- - -




Sleeve Bearings

Split Sleeve bearings are used in motors intended for direct connection to drivenunits. They are split at the horizontal centerline and are held together with two dowelpins and two screws. Bearing housings and capsules are also split. This permits inspectionof the motor windings without complete disassembly of the bearing arrangement. Splitbearings may also be changed without disturbing the coupling.

Babbitt Material

Standard bearings consist of babbitt material liner in either a cast iron or steelshell, which is bonded to the shell. The bonding consists of chemically removing theexposed graphite in the cast iron, tinning the cast iron surface and pouring the babbitt toadhere to the tinned surface.

The steel shell will go through a similar process, but does not need to bechemically cleaned on its surface.The babbitt used is high in tin with its compositionbeing close to SAE-11 and SAE-12.

Specifically it is:(1) Tin 89.0 %(2) Antimony 7.5 %(3) Copper 3.5 %

Bearing Clearance

Normal bearing clearance will usually be from .001-in. to .002-in. for each inch ofshaft journal diameter. Drawing tolerances permit a plus .002-in. to .003-in. variation.The primary function of bearing clearance is to provide a wedge-shaped space at eachside of the journal as it rests on the bearing. As the shaft rotates, it pulls oil into thewedge. From the wedge, oil is pulled into the loaded area where it builds up a filmpressure sufficient to carry the shaft. The amount of load the film can carry is dependent,among other things, on the area of the pressure film.




Sleeve Bearings

Journal and Bearing Finish

The most important aspect in the operation of a sleeve bearing is the surfacefinish of the journal and bearing. A surface that is not smooth will permit the oil to fillthese pockets and an insufficient oil film will form. The shaft journal should be polishedwith crocus cloth. The bearing babbitt should have a finish of 32 micro-inches.

The shaft journal should be near perfectly round as an out-of-round shaft maycause vibration and pounding out of the babbitt.

Alignment and Coupling of Flexibly Coupled Sleeve Bearing Motors

Since sleeve bearings are capable of carrying only momentary thrust, it isessential they be protected from all continuous thrust. All sources of damaging thrust areexternal to the motor. If the driven unit can develop thrust, it must have its own thrustbearing. Other possible sources of external thrust are the shaft is not level and/or there ismisalignment of flexible, free-floating type of couplings.

It is recognized shafts must be level, but the problem of coupling alignment is notso readily controlled. Good coupling alignment ordinarily eliminates coupling thrust onsmall motors. On larger motors; however, and particularly those operating at high speed,even the best practical alignment of the free floating type of coupling does not assurefreedom from thrust developed within the coupling.

Motor End Play and Limited End Float of Couplings

The limited end float coupling successfully prevents thrust from being transmittedto the bearings of the motor because the maximum end float, inherent to the coupling, isless than the total end play of the motor. Any thrust developed, which tends to separatethe two halves of the coupling, is restrained by lips located at the ends of the couplingcover (Figure 3.12). Thrust tending to bring the coupling halves closer together isrestrained by buttons located in the ends of the respective shafts.




Sleeve Bearings

Setting of End Play

Figure 3.12 below shows the nominal values of motor end play. Thearrangement is shown with a gear-type coupling, but applies also for pin and bushing orspring grid type couplings.

Dimensions in the figure are for nominal values of motor end play. (Refer toNational Electrical Manufacturers Association Catalog for Motors and Generators MG1-2003). Motor end play has a tolerance and may vary from nominal value. Nameplates onmotors give data on actual end play when limited end float of coupling is required. Anyvariation of actual end play from nominal should be divided evenly betweencompensations to be made in B and C.

Figure 3.12. Nominal Values of End Play Settings




Sleeve Bearings

Self-Centering Couplings with Semi-Restricted End Play

The following types of couplings may be used without modification where limitedend float couplings are specified:• The laminated metal disc type.• The rubber-tire type (if designed for the speed).

These types of couplings are considered to be free from development of thrustand are approved for applications to motors of any rating and end play. No spacers,buttons, etc., are required to limit coupling float. When these couplings are used, themotor must be located relative to the driven unit so that the motor shaft is in the centerof its end float. (Referring to motor in Figure 4.4.11, B will equal C).

Unrestricted or Free Floating Couplings

Without modification, the following types of couplings have unlimited end playand are classed as free floating:

• Pin and Bushing Type.• Spring Grid Type.• Gear Type.

Limited end float models, or versions of these couplings, are available fromseveral coupling manufacturers. Some means of limiting end float are discussed below.

Pin and Bushing Type – The end float of this type of coupling may be limited through theuse of two special pins located at diametrically opposite positions. A spacer washer ismounted on each of these enlarged head pins. The details depend upon the particularcoupling design.

Spring Grid Type – End float can be limited with spacer plates or buttons located betweenshaft ends in conjunction with half-oval soft steel or copper inserts placed in the loops ofthe spring. These inserts are to be symmetrically located so as not to cause unbalance.

Gear Type – Spacer plates, or buttons located between shaft ends, may limit end float ofthis type of coupling. Hollow spacer-type couplings require plates at each end of thespacer.




Sleeve Bearings

Unrestricted or Free Floating Couplings – cont.

Generally, the above methods are preferred for limitation of end float in free-floating types of couplings. Spacer plates, spacer washers or buttons may be omitted atuser’s discretion.

The end float of free floating-type couplings can be limited by pressing one, orboth, coupling hubs farther back on the shaft. Objections to this method are sometimesraised because the shaft ends may touch and it’s uncertain the hub will be placed backexactly in the same position if it’s temporarily removed.

Mechanical Center Adjustment

To adjust the mechanical center of bearings to the magnetic center of the rotor,shims are used in the bearing housing on either side of the flanged portion of thebearing. To determine how close the magnetic center is, in relation to the mechanicalcenter, mark the shaft while the motor is running. Stop the motor and rotate the shaft byhand, marking the shaft when it is pushed and pulled in each direction.

The shims are set at the factory and generally need not be rearranged, even whena new bearing is installed. The rotor core is mounted precisely on the shaft so the twocenters line up.




Lubrication

One of the most frequent questions asked is how to translate lubricationrequirements, defined in our instruction books or nameplates, into specifications that willmatch products available from lubricant suppliers. Not one lubricant is satisfactory for alluses. Speed, load, temperature, vibration and bearing configuration will affect the typeof lubricant used. The intent of this section is to give a list of suppliers of oils and greasesfor use in various bearing types and applications. In addition, some of the basicterminology used in lubricants is defined.

Terminology

Penetration - is a measure of the grease consistency (hardness or stiffness). Grades(NLGI) 2 and 3 are the most common used in electrical motors with grade 3 being thestiffer. Stiffer greases are used where they must stay in place without slumping, such asin large vertical motors.

Rust Inhibitor – is a polar additive, which adheres to metallic surfaces to provideprotection against moisture.

Oxidation Inhibitor – is an additive that helps resist chemical changes in the oil orgrease caused by aging or high temperatures.

Extreme Pressure (EP) – resistance is a property of grease that permits bearings to takevery heavy loads and shocks. High viscosity oil is usually used in this type of grease.

Viscosity – is the resistance of an oil to flow at a given temperature. The most commonmeasure in the United States is Saybolt Universal Seconds (SUS) The proper viscosity isnecessary to provide sufficient film between rotating parts.

Non-Foaming Oil – is one in which an additive has been used to reduce the surfacetension of the oil, thus preventing foaming.

Turbine Oil – is high quality, inhibited oil specially refined to give long life.




Lubrication – Anti-friction Bearings

Grease

At Norwood, our standard is No. 2 grease (Mobil Polyrex EM NLGI 2). It ispremium type grease with a polyurea base, which gives longer life at highertemperatures. This grease is suitable for Class B and F insulated motors. It is used forstandard ball bearing motors, as well as motors having roller bearings suitable for beltdrives.

Table 3.7. Grease Capacity for different shaft ends and lengths

Frame

OppositeShaft End

Bearing (oz)

Shaft End BearingShortShaft(oz)

LongShaft(oz)

449 CGZ 3600 RPM 18 20 -449 CGZ 1800/Slower 18 20 20S449 CGZ 3600 RPM 14 16 -

449 CGZ 1800/Slower 14 16 28500 CG-CGZ 3600 RPM 13 13 -

500CG-CGZ 1800/Slower 13 13 20580 CG-CGZ 3600 RPM 13 13 -

580 CG-CGZ 1800/Slower 24 20 20680 CG 1800/Slower 26 26 -8010 CG1800/Slower 150 155 -

8012 CG 1200/Slower RPM 150 155 -880 1800/Slower 26 26 -

SH400 CGZ 1800/Slower RPM 30 30 -SH450 CGZ 1800/Slower RPM 35 35 -

SH560 1LA4 49 49 -SH630 1RA4, horizontal 44 44 -

SH630 1RA4, vertical 88 88 -SH630 1LA4 49 49 -

SH 710 1500/Slower RPM 200 200 -





Grease Types

Polyrex EM NLGI 2 by Mobil as standard for all machines with an operatingbearing temperature above -25 °C.

Mobilith SHC 100 by Mobil as standard for all machines with an operating bearingtemperature below -25 °C.

Table 3.8. Group I-NLGI #2 MultipurposeManufacturer Manufacturer’s Trade

NameChevron Oil Company SRI #2Mobil Oil Corporation Polyrex EM NLGI 2

Mobilith SHC 100Shell Oil Company Dolium R

Darina #2CyprinaStamina RLS 2

Texaco Oil Company Polystar Synthetic 1002

Table 3.9. Group III-Extreme PressureManufacturer Manufacturer’s Trade

NameExtreme Pressure (EP)

Additive NLGI #2 GreaseMobil Oil Corporation Mobilux EP#2Chevron Oil Company Industrial Grease Dura Lith EP#2Exxon Lidox EP#2Shell Oil Company Darina EP#2BP Oil Company Bearing Gard EP#2Texaco Oil Company Multifak EP#2

Note: Mixing of different base greases is not recommended. The greases above mayhave different bases which may or may not be compatible with the grease supplied in thebearings from the factory.





Lubrication Frequency

Prior to shipment, motor bearings are lubricated with the proper amount andgrade of grease to provide satisfactory service under normal operating conditions. It isgood practice; however, to visually check bearing grease of newly installed motors forproper lubrication after a few months of operation.

All anti-friction bearing motors designed for unusual service conditions, requiringspecial lubrication, will come with a plate containing lubricating instructions. Theinstructions on such a plate take precedence over this manual and should be followed toachieve optimum bearing life and to avoid consequential damage to rotating parts.

NOTE: A common mistake is over-lubrication of bearings, which can result in hotterrunning bearings. When grease is added without removing the drain plug, the excessgrease must go somewhere and is usually forced into and through the inner bearing cap,eventually ending up in the windings. Proper lubrication is essential, but some under-lubrication is less dangerous than over-lubrication.

Mixing greases of different bases can soften them, resulting in poor lubrication.Removal of all old grease is recommended before using a grease of a different base.

Operating temperature range should be from –15ºF to + 250ºF for Class Binsulation and to +300ºF for Class F and H. Most leading oil companies have specialbearing greases that are satisfactory. For specific recommendations, consult the motorlubrication plate drawing or the factory.

The frequency of re-lubricating bearings depends on three factors – speed, typeof bearing and service. As a guide, the following is recommended.

The frequency of re-lubrication in Table 3.10 is based on bearings normally used.If the motor has special bearings, consult the motor outline, the motor lubrication plate,or the factory for possible special requirements.





Lubrication Frequency – continued

Table 3.10. Recommended Frequency of Re-Lubrication

DirectConnected

Motor Speed Re-lubrication Frequency*

3600 or 3000 4 months or 2000 operating hours1800 or less 6 months or 3000 operating hours

Belt Drive1800 3 months or 1500 operating hours1200 3 months or 1500 operating hours900 3 months or 3000 operating hours

* Whichever comes first, operating environment or application may dictate morefrequent lubrication.

Re-lubricate horizontal shaft motors as follows:1. Stop the motor and lock out the switch.2. Thoroughly clean and remove grease inlet plug and drain pipe from the outer

bearing caps or housing.3. Add grease to inlet with handgun until small amount of new grease is forced

out of drain. Catch used grease in suitable container.4. Remove excess grease from ports and replace inlet plug only.5. Run at least one hour to expel any excess grease from drain opening.6. Clean old grease from drainpipe. Replace cleaned drainpipe and drain plug.7. Put the unit back in operation.





Pure Oil Mist

As outlined earlier, our standard lubrication for anti-friction bearings is grease. As anoption we can also offer oil mist lubrication for anti-friction bearings. Please note, weprovide provisions only for the customer, it is the end users responsibility to provide theoil mist lubrication system including:

- Air filter- Air pressure regulator- Oil mist generator- Mist distribution manifold- Application fittings- Oil mist orifice fittings

For this option, we provide a specially treated stator, specially sealed bearinghousings and stub piping for the customer to pipe up to. Please refer to factory for inletand outlet pipe sizes (typically 0.75-in. NPT inlet and 0.375-in. NPT outlet).

Table 3.11. Bearing Size and Service

Bearing Size Moderate Service (CFM) Heavy Service (CFM)

313 0.064 0.128315 0.074 0.148316 0.079 0.158318 0.088 0.177319 0.094 0.187320 0.098 0.197222 0.108 0.216

226 0.128 0.256Note: Oil to Air Ratio: 0.4 in3/ hr /CFM of air




Lubrication- Sleeve Bearings

Oils

High-grade oil with an oxidation and rust inhibitor should be used. It should havea viscosity index NO LOWER than 90. The higher the viscosity index results in better oilfilm at higher temperatures. The viscosity of the oil needed depends upon the unitpressure on the bearing, speed, and the ambient/operating temperatures. The operatorhas no control of the above factors, but should record the oil temperatures periodically tonote any great change in temperature. The following viscosities should be used:

Table 3.12. Viscosity relating to Motor SppedISO Grade SUS at 100°F Speed (rpm)32 150 360068 300 1800 and slower

If the oil temperature exceeds 175°F on 1800 and 3600 RPM motors or 150°F on1200 RPM and slower motors, use the next highest viscosity oil. Generally, the bearingtemperature will run approximately 8°F higher than the oil temperature.




Lubrication - Sleeve Bearings

Oils

Viscosity grade numbers for industrial high-grade turbine oils are from theInternational Standards Organization (ISO) viscosity classification system (ISO 3448). TheAmerican Society of Testing Materials (ASTM) has adopted the ISO system.

The ISO grade system is based on kinematic viscosity (centistokes) at 40ºC(104ºF). It is abbreviated cSt. The former ASTM system was based on Saybolt UniversalSeconds (SUS) at 100º F (37.8ºC).

The following list shows five of the 18 ISO grades of oil that are commonly usedfor electric motor bearings. The list compares the new designations with the old.

Table 3.13. ISO Viscosity Ranges in Centistokes and Saybolt Universal SecondsISO Viscosity Grade

NumberISO Viscosity Range (cSt

at 40°C)Viscosity Range (SUS) at

100°F32 28.8 - 35.2 140 - 16046 41.4 - 50.6 200 - 25068 61.2 - 74.8 290 - 350

100 90 - 110 450 - 500

150 135 - 165 700 - 800

Table 3.14. Sleeve Bearing MotorsViscosity (SUS at 100°F) ISO Grade Speed

140-160 32 3600 / 3000290-350 68 1800 & Slower

Table 3.15. Angular Contact Thrust Ball BearingsViscosity (SUS at 100°F) ISO Grade Speed

140-160 32 3600290-350 68 1800 & Slower

Table 3.16. Spherical Roller Thrust BearingsViscosity (SUS at 100°F) ISO Grade Speed

700-800 150 1800 & Slower





Oils – cont.

Kingsbury Thrust Bearings:

This plate-type bearing is water cooled for all speeds. Its thrust capacity isdependent upon speed and oil viscosity. The capacity may be increased by as much as30% over its nominal value by increasing the oil viscosity; however, increasing the oilviscosity generates more heat, which may require more cooling.

Table 3.17. Kingsbury Thrust BearingsViscosity (SUS at 100°F) ISO Grade Speed

300-350 68 All speeds Normal Thrust450-500 100 All speeds Extra Thrust

Table 3.18. Lubrication Oils for Ball, Roller and Sleeve Bearing Motors

ManufacturerManufacturerTrade Name

Manufacturer’s Grade or Type DesignationViscosity (ISO)

32 46 68 100 150

ChevronChevron EP

Machine- - #68 #100 #150

Citgo Pacemaker #32 #46 #68 #100 #150Exxon Teresstic #32 #46 #68 #100 #150

Nuto #32 #46 #68 #100 #150Mobil D.T.E. Light Med. Hvy./Med. Hvy. Extra/Hvy

Phillips Magnus #32 #46 #68 #100 #150Shell Telius T #32 #46 #68 #100 #150

Sun OilCompany

Sunvis 900Series

#32 #46 #68 #100 #150





Oils – cont.

Motors with sleeve bearings are shipped without oil. A rust-inhibiting film is appliedat the factory to protect bearing and journal surfaces during shipment. Before attemptingto operate any sleeve bearing motor, the following steps must be performed.

1. Visually inspect the bearing condition. Oil ring inspection ports and drain opening inthe housing are normally provided for this purpose.

2. Check for any accumulation of moisture. If oxidation is discovered, all traces of it mustbe removed before machine is put in service.

3. Flush all oil piping. Fill bearings reservoirs to normal level.NOTE: If the oil temperature exceeds 175°F on 1800 and 3600 rpm motors or 150°Fon 1200 rpm and slower motors, use the next higher viscosity oil. If operatingtemperature is not known, consult factory for suggested oil selection.

4. Oil reservoirs should be filled to mark indicated on gauge or center of gauge.CAUTION: Improper lubrication can cause equipment damage. Refer to lubricationinstructions on motor or in this manual.

5. Rotate shaft several turns by hand to distribute oil over bearing parts. Make sure oilrings rotate freely.

It is important to maintain the correct oil level, as lack of lubrication is often the causeof bearing failure. Inspect oil level and oil ring operation frequently. Oil ring operationcan be observed through the sight glass mounted on the top of the bearing capsule. Oilrings should be perfectly round, free of burrs or rough edges, turn at constant speed andcarry a noticeable amount of oil to the top of the journal. Failure of the oil ring to turnfreely may be caused by:

1. Ring out of round (should be round to .062 inch).2. Fouling on a projection of the bearing bushing.3. Ring not balanced (heavy side will tend to remain down).4. Adhesion to guide slot (trapezoidal section reduces adhesion).5. Oil too cold or viscous, or oil level too high.6. Shaft not level, oil ring tends to bind.





Oils – cont.

At the first sign of oil discoloration or contamination, replace with new oil.Bearing wear, often from vibration or thrust, causes rapid discoloration. Change oil asrequired to keep clean.

Oil Mist Purge

In certain especially harsh applications, it is advantageous to ensure that certainairborne contaminants do not have the ability to enter the bearing housing of sleevebearing machines. To prevent this problem, we offer an oil mist purge system. Thissystem, when applied to sleeve bearing oil ring lubricated bearings, provides a positivepressure above the oil level in the housing during both operation and shut down.

Sleeve bearing motors require the following modifications to convert to oil mist purge:

1. The bearing housing must be fitted with a vent to allow the positive air/oilpressure in the housing to escape outside the motor.

2. A constant level oiler assembly must be used on each bearing and fitted with anoverflow provision to ensure condensed oil does not increase the oil level insidethe bearing housing. If the motor has provisions for flood lubrication, the oilersare not required, as any excess oil will drain out of the oil outlet piping.

3. The area between the motor and the terminal box must be sealed to preventany oil mist from getting into the terminal box.

NOTE: The customer supplies the external oil mist system. Siemens will supply theprovisions only.

Cleanliness

The maintenance and care of electric motors includes cleanliness, particularly inthe area of the bearings. The oil cavity must be kept clean and is generally painted with awhite sealer to prevent any sand from getting into the oil. When a bearing isdisassembled for any reason, the cavity should be flushed out, cleaned, and covered tokeep out dust and dirt. Small dirt particles have embedded themselves in the soft babbittwith no effects on the operation; however, it has been seen where one particle caught inthe journal has plowed itself into the babbitt and caused a failure. It is important the oilbe changed and flushed out as suggested before adding new oil.





Flood Lube Requirements and Heat Rejection Rates

Table 3.19. 3600 RPM - Lube Oil 140 - 160 SUS @ 100°F (ISO VG 32)Frame Size/Type Flood Lube GPM / BRG

(optional/required)Heat Rejection Rate(BTU/minute/BRG)

500 TEFC 0.15 (optional) 19.1500 WPI and WPII 0.15 (optional) 19.1588/5810 TEFC 0.3 (optional) 31.35812 TEFC 0.3 (required) 31.3580 WPI,WPII 0.15 (optional) 15.6SH400 0.5 (required) 29.7SH450 0.5 (required) 29.7880 1.0 (required) 47.5

680 WPI, WPII, CAZ 0.5 (optional on WPI & WPII, required CAZ) 43.7800 WPI, WPII, CAZ 1.25 (required) 105.0SH560 1.06 (required) 53.3SH630 1.59 (required) 211SH710 3.17 (required) 455Table 3.20. 1800 RPM & Slower - Lube Oil 290-530 SUS @ 100°F (ISO VG 68)

Frame Size/Type Flood Lube GPM/BRG (optional/required) Heat Rejection Rate(BTU/minute/BRG)

500 0.15 (optional) 14.2580 TEFC 0.3 (optional) 23.2580 WPI,WPII, CAZ 0.15 (optional) 23.2SH400 / SH450 0.5 4Pole, 0.3 6P+ (optional) 33.5 4P, 20.1 6P+880 0.75 (4Pole required, 6Pole optional) 38.2680 WPI, WPII, CAZ 0.5 (optional) 32.0800 WPI, WPII 1.00 (optional) 81.1800 CAZ 1.00 (4P required, 6P+ optional) 81.1

SH5600.79 4-6Pole, 0.52 8P+

(4-8P required, 10P+ optional) 48.9 4-6P, 32.2 8P+SH630 2.11 (optional) Consult FactorySH710 2.11 (4P, required), 1.58 (6P+ optional) Consult FactoryNotes:

(1) Flood lube oil pressure must be specified at time oforder

(2) Ambient of 50°C or higher will require flood lubrication




V-Belt Applications

Motors to be used on V-belt drive applications normally have different shaftlengths and diameters as compared to direct drive motors. They also tend to havecylindrical roller bearings on the drive end. Cylindrical roller bearings are chosen becausethey can support greater radial loads than deep groove ball bearings.

Note: If a customer wants to know their exact belt pull to ensure it is under theMaximum limit, you will need the following information.

1. Belt Groove Geometry: i.e. 8V2. Number of Belts/Grooves: i.e. 12 belts3. Driver Speed (motor): i.e. 1778 [rpm]4. Driven Speed (load): i.e. 500 [rpm]5. Driver Sheave Diameter (motor): i.e. 9 [in]6. Driven Sheave Diameter (load): i.e. 32 [in]7. Center – to – Center Distance: i.e. 65 [in]8. Horsepower: i.e. 600 [hp]9. Service Factor: i.e. 1.15




V-Belt Applications

Sheave Location

The certified motor outline drawing will specify the location of the sheave.Typically, this location will be in the center of the full keyway. In the absence of anoutline drawing, the maximum distance from the sheave groove centerline to the shaftextension shoulder should not exceed 5.5 inches.

Table 3.21a. Max. Belt Pull Limits

HP FRAME

Type CG(ODP/WPI)

Type CGII (WPII)(Requires NU2226DE

and 6222 NDEBearings)

Max. Belt Pull(lbs)

Max. Belt Pull (lbs)

4 Pole1785RPM

900 5010 6,8701 6,7401

800 5010 6,8701 6,7401

700 5010 6,8701 6,7401

600 508 6,4301 5,9001

500 508 6,4301 5,9001

450 508 6,4301 5,9001

400 508 6,330 5,9001

350 508 5,730 5,730300 508 5,080 5,080250 508 4,560 4,560200 508 3,950 3,950150 508 3,230 3,230

* Based on belt drive shaft extension where shaft diameter, (U) = 4.000 Inches and thelength beyond the shaft extension shoulder, (N-W) = 9.50 inches. For belt drives with anyother shaft extension please consult the Norwood Factory.1 Max. belt pull is limited by an L10 brg life of 17,500 hours.




V-Belt Applications

Max. Belt Pull Limits

Table 3.21b. Max. Belt Pull Limits

HP FRAME

Type CG(ODP/WPI)

Type CGII (WPII)(Requires NU2226DE

and 6222 NDEBearings)

Max. Belt Pull(lbs)

Max. Belt Pull (lbs)

6 Pole1185RPM

600 5010 7,8001 6,3002

500 5010 7,8001 6,3002

450 5010 7,8001 6,3002

400 508 7,5401 6,3002

350 508 7,540 6,3002

300 508 6,700 6,3002

250 508 5,950 5,950200 508 5,100 5,100150 508 4,290 4,290

8 Pole885 RPM

400 5010 8,5301 6,3002

350 5010 8,5301 6,3002

300 508 8,3601 6,3002

250 508 7250 6,3002

200 508 6170 6170150 508 5120 5120125 508 4600 4600100 508 4,000 4,000

* Based on belt drive shaft extension where shaft diameter, (U) = 4.000 Inches and thelength beyond the shaft extension shoulder, (N-W) = 9.50 inches. For belt drives with anyother shaft extension please consult the Norwood Factory.1 Max. belt pull is limited by an L10 brg life of 17,500 hours. Min. sheave dia. wasincreased to maintain this limit.2 Max. belt pull is limited by a shaft bending stress of 10,000 psi. Min. sheave dia. wasincreased to maintain this limit.




V-Belt Applications

Table 3.21c. Max Belt Pull Limits for 500 Frame TEFC

HPMax. Belt Pull

(lbs)

4 Pole 1785RPM

8001 7,0101

7001 7,0101

600 6,970500 6,970450 6,670400 6,330350 5,730300 5,080250 4,560200 3,950150 3,230125 2,830100 2,500

6 Pole 1185RPM

5001 8,0101

4501 8,0101

400 7,940350 7,580300 6,700250 5,950200 5,100150 4,290

8 Pole 885RPM

3501 8,8101

3001 8,8101

250 7,250200 6,170150 5,120125 4,600

* Based on belt drive shaft extension where shaft diameter, (U) = 4.000 Inches and thelength beyond the shaft extension shoulder, (N-W) = 9.50 inches. For belt drives with anyother shaft extension please consult the Norwood Factory.1 Max. belt pull is limited by an L10 brg life of 17,500 hours. Min. sheave dia. wasincreased to maintain this limit.




V-Belt ApplicationsTable 3.21d. Max Belt Pull for 588 & 5810 Frames for ODP/WPI/WPII

HP Max. Belt Pull (lbs)

4 Pole1785 RPM

700 8,970600 8,130500 7,190

6 Pole1185 RPM

600 10,720500 9,400450 8,930

8 Pole 885RPM

500 11,670450 10,760400 9,810350 9,050300 8,200

Table 3.21e. Max Belt Pull Limits for 580 Frame TEFC

HP Max. Belt Pull (lbs)

4 Pole1785 RPM

800 9,990700 8,970600 8,130500 7,190450 6,670400 6,330

6 Pole1185 RPM

600 10,720500 9,400450 8,930400 8,160350 7,580300 6,700

8 Pole 885RPM

450 10,760400 9,810350 9,050300 8,200250 7,250200 6,170

* Above charts based on belt drive shaft extension where shaft diameter, (U) = 4.875Inches and the length beyond the shaft extension shoulder, (N-W) = 14.62 inches. Forbelt drives with any other shaft extension please consult the Norwood Factory.




Standard Paint Process – Norwood Plant

An epoxy coating system is the standard finish on motors at the Norwood Plant.The present color is Siemens Motor Blue. A high quality primer is applied to all castings atthe foundry and, except for machined surfaces, remains on the finished motor. Allfabricated parts (either purchased or manufactured in-house) are primed with a highquality primer compatible with the finish coat.

The resistance of the epoxy finish coat to acids and alkali metals is generallybetter than air-dried alkyd paints. Epoxy finishes have proven themselves as long lastingpaints in a wide range of adverse environments. In general, industry accepts epoxies forsevere environments.

Naturally, the stainless steel nameplate and instruction plates are not painted.The shaft extension is also unpainted but does receive a coating of a rust preventative toprotect the shaft until it’s time to place the motor in service.

Prime Coat

Iron castings are blast cleaned at the foundry and primed with a high qualityprimer compatible with the finish paint. If re-priming is required at the Norwood Plant,they receive a 1-4 mil coat of a compatible primer. Steel fabrications and miscellaneousparts also receive a 1-4 mil coat of a compatible primer. (A mil measures at one-thousandth of an inch).

Stator Assemblies

Stator assemblies with laminations stacked in the yoke receive a coating of epoxy(polyester on low voltage, random wound motors) on most surfaces during the statortreatment cycle. These coatings offer excellent corrosion protection and are compatiblewith most finish coats of paint. It is recommended this coating not be removed duringany subsequent processing. It is difficult to obtain as good a protection coat by othermeans.

Oil Reservoirs

Internal surfaces that come in contact with the lubricating oil, such as oil wellcavities of bearing brackets and cartridges, are treated with a special polyurethane sealer.




Paint Process Standard – Norwood Plant cont.

Rotors

When specified, rotors receive a coat of a special 2-part epoxy paint to preventrust. The epoxy is applied after the rotor is turned to size and all surfaces including therotor laminations, end heads, fans and exposed portions of shafts are painted. Even theshaft and support arms under the rotor core on slow speed machines receive thisprotective treatment.

Finish Coat

The standard finish coat for all motors manufactured at the Norwood Plant is a 4-8 mil thick coating of 2-part epoxy paint. All machines are painted Siemens Motor Blue.Other colors can be supplied. All exposed, unpainted metal parts, except nameplates, arecoated with a rust preventative.

Special Paint Process

Special surface preparations, primers and finish coatings require additional timeand effort, resulting in higher manufacturing costs. Many primers and finish coatings,widely used in the past, have been identified as dangerous to apply and are no longerapplied at the Norwood Plant. Availability of such finishes depends on success in locatinga properly equipped subcontractor for the treatment process. Consult factory for priceand availability. When special finish coats can be applied directly over the standardprimers, a substantial cost savings can be realized.

Some special primers can only be applied after removal of the existing primer byan expensive blast cleaning process. We discourage the removal of this coating andrecommend, instead, the use of an intermediate coating with epoxy. Special treatmentsor materials to be used on parts or on the total machine must be individually evaluatedbefore we can agree to supply them.




Motor Rotation

Table 3.22. Unidirectional MotorsFrame Type(s) SpeedsS449 1LA 3600500 All 3600580 All 3600SH400 CGZ 3600SH450 CGZ, CGZV 3600 & 1800880 CGZ, CGZV 3600 & 1800680 CG, CGII, CAZ, CGGS 3600680 CG, CGII (vertical) 1800 and slower800 CG, CGII, CAZ, CGGS 3600800 CG, CGII (vertical) 1800 and slowerSH560 1LA4 3600SH630 1RQ AllSH710 1RP, 1RQ,1RN 3600 & 1800NOTE:1. All 2-pole verticals with non-reverse features are unidirectional.2. CAZ/1RQ are all unidirectional.3. CAZBB motors are bi-directional at all speeds




Sound Pressure Levels

Noise Requirements

Typical no load, free field noise levels of standard design motors are shownbelow. For guaranteed levels, add 2 dba to the levels below those shown in the followingchart.

Table 3.23. Typical Overall Level ‘A’ Scale (dbA at 1 Meter)

Enclosure Frame3600RPM

1800RPM

1200RPM

900 RPM &Slower

ODP/ WPI

500 91 84 85 85580 83 83 85 83680 86 83 95 95800 88 86 85 85

WPII

500 90 81 82 82580 82 83 85 83680 84 82 86 83800 85 84 85 85

SH630 90 80 84 84SH710 90 81 80 83

TEFC

509 / 5011 86 85 80 805013 88 88 80 80580 87 86 80 80880 85 89 88 80

SH400 88 82 81 80SH450 88 84 87 80SH560 86 87 83 81

TEAAC

580 90 82 82 82680 89 84 84 84800 87 89 87 87

SH630 97 95 86 85SH710 85 85 88 87

NOTE: Lower noise levels are available. Refer requirements to factory for price and availability.Lower noise level designs may affect motor dimensions. Refer to SNAP or the factory for details.




Mechanical Modifications for Low Temperature Motors

Table 3.24. Temperature Levels related to Mechanical Modifications

Temperature Grease in Brg.Housing

Anti-FrictionBearings Shaft Yoke and Brg.

Housing Rules

80°F

60°F

40°F

20°F

0°F

-20°F

-40°F

-60°F-65°F

Below Minus (-)65°F. Each case

is to beconsidered

separately; acheck is to be

made of bearingand shaft load

speeds, shock orvibration. Etc.

Polyrex EM NLGI2

Mobilith SHC100

StandardMaterials

StandardMaterials with

Special Grease

Standard

Standard

Normalized Steel

Silicone Grease(Limited in speed

and loadcapability)

Special Materialswith Special

Grease




Vibration & Critical Speeds

Causes of Vibration

Some possible sources of vibration excitation in electric motors are:• Unbalance in the rotor system.• Eccentric rotor.• Uneven air gap.• Open rotor bar (broken bar, poor braze joint, or casting void).• Bearing oil-film instabilities (whirl or whip).• Internal rubs (oil guard rubs).• Misalignment at bearing or at coupling.• Looseness in rotor or bearing supports.• Anti-friction bearing dissymmetry.• Thermal bow of shaft, rotor assembly.• Frame or foundation distortion.• Operation at or near resonance or critical speed without sufficient damping.

Vibration Measurement

Vibration is commonly measured at the following locations:1. Bearing Housing – measured in the Vertical, Horizontal and Axial directions onboth ends of the motor.2. Shaft radial vibration– usually taken only on sleeve bearing motors and may betaken by the following methods:

a. StickWhere there are no special measurement provisions made, vibration ismeasured with a shaft stick or rider on or adjacent to the drive end shaftextension. Readings are also taken on the opposite end if a shaft extensionor shoulder is available. Readings are commonly taken in the vertical andhorizontal directions. This gives absolute shaft vibration.

b. Proximity ProbesWhere proximity probes are specified or available, vibration is measured oneach end of the motor, usually at two locations, 90 degrees apart andusually at ±45 degrees from the vertical upward direction. These readingsgive relative vibration between the shaft and housing.

c. Units of Measurement (Housing and shaft stick measurements may be ineither of the following units):

1. Displacement Amplitude – Mils (.001 in.) peak-to-peak doubleamplitude. (proximity probe readings)

2. Velocity – Inches per second peak velocity





Vibration Limits

Vibration requirements for motors may be specified in accordance with variouscustomer standards or per industry standards such as NEMA (ANSI) or API Standard 541.

NEMA Limits

Listed below are vibration limits given in NEMA standards for machines testedwith rigid mounting. (Shown in MG1-2016, Part 7).

Table 3.25. Vibration Limits for machines tested with Rigid MountingSynchronous

RPMHousing

(Velocity; in./sec. peak)Shaft

(Displacement, mils pk-to-pk)3600 0.12 1.91800 0.12 1.91200 0.12 1.9900 0.12 1.9720 0.12 1.9600 0.12 1.9

Note: Limits are for Grade “A”, uncoupled, no load operation in factory test. NEMAFrame>440.





API Limits

Vibration limits for motors are also given in API Standard 541, fifth edition, Dec2014. These are given in chart form with charts for vibration measured on the shaft ofsleeve bearing machines and on the bearing housings for sleeve and ball bearingmachines.

Table 3.26. Vibration LimitsBearing Housing (2-6 Pole)

in./sec. peakShaft (all speeds) using

prox. probe mils pk-to-pkUnfiltered 0.10 1.5

1xRPM 0.10 1.22xRPM 0.10 0.5

Runout (a) - 0.45Notes: Runout is total electrical and mechanical runout as measured by proximity probesat slow roll.

Practices Employed to Achieve Low Vibration

Some of the features and practices employed to achieve very low vibration in twopole motors are given below:

• Precision design and manufacture of rotor parts for size and concentricity.• Interference fits between shaft and rotor core and fans that remain light atspeed and temperature.• High precision balance at running speed.• Very low shaft runout.• Proximity probe sensing areas and journals are ground simultaneously toconcentricity within .0002 inch or less.• Probe sensing surfaces are burnished and demagnetized and shaft materials arehigh-grade steels to reduce electrical runouts.• Precision machined rotor assemblies. Two pole rotor cores typically are groundwith runouts of .001 inch or less• High quality cast aluminum rotors without voids.• Copper rotor bars shimmed tight and designed to prevent breakage.• Induction brazed copper rotor bar-to-end ring joints.• Machines built and checked for uniform air gap.• Rugged frame and bearing housing structures.• Self-aligning bearings of superior design.• Precision machining for good alignment of parts and low distortion.





• Multi-circuit windings to reduce unbalanced magnetic pull.• Reduced machine ratings for very low vibration.• Machine critical speeds or resonances removed from operating speed and/orhighly damped.• Thorough, state-of-the-art, vibration testing, cold and hot.

Critical Speeds and Damped Rotor Resonance

The term “critical speed” was devised in the late 1800’s in connection with factoryoverhead pulley shafting. Some investigators at that time incorrectly thought it to be anunstable condition, since at certain speeds shafts were observed to develop very largevibrations. Presently, we have the general understanding that critical speed of a shaft isthe speed in RPM, which is equal to the frequency of the shaft lateral natural vibration incycles per minute. It is also known as the rotor-shaft system resonance speed.

Since the advent of high-speed computers, a whole technology of Rotor DynamicsAnalysis has been developed. We now have programs at Norwood which allow thecomplete rotor dynamic system to be taken into account, including the rotor structureand mass, bearing properties for oil film or anti-friction bearings, and bearing supportstiffness and mass. These programs are capable of calculating a synchronous responsecurve approximating the vibration amplitude vs. speed curve of an actual motor coastdown. Undamped critical speed plots and system stability calculations can also be made

These present day analyses, particularly with cylindrical partial arc sleeve bearings,show the importance of the system resonance speed (critical speed) and the systemamplification factor, which is determined primarily by bearing damping. Bearing dampingis generally high with sleeve bearings. In many cases, this damping approaches the levelof “critical damping” which prevents oscillations under free harmonic vibration. It hasbeen found to have stable vibration even when resonance speed corresponds tooperating speed. This effect of damping on rotating system performance has beenrecognized and included in the requirements for “Critical Speed” given in API Standard617, Fifth Edition for Centrifugal Compressors. An excerpt from this standard is givenbelow. NOTE: The latest version of this standard is the 8th Edition, but has not yet beenpurchased by the factory.




2.9 Dynamics2.9.1 Critical Speeds2.9.1.1 When the frequency of a periodic forcing phenomenon (exciting frequency)applied to a rotor bearing support system corresponds to a natural frequency of thatsystem; the system may be in a state of resonance.

2.9.1.2 A rotor-bearing support system in resonance will have its normal vibrationdisplacement amplified.

The magnitude of amplification and the rate of phase-angle change are related to theamount of damping in the system and the mode shape taken by the rotor.

Note: The mode shapes are commonly referred to as the first rigid (translatory orbouncing) mode, the second rigid (conical or rocking) mode, and the (first, second, third,…. , nth) bending mode.

2.9.1.3 When the rotor amplification factor (see Figure 8), as measured at the vibrationprobe, is greater than or equal to 2.5, that frequency is called critical and thecorresponding shaft rotational frequency is called a critical speed. For the purposes ofthis standard, a critically damped system is one in which the amplification factor is lessthan 2.5.

2.9.1.4 Critical speeds shall be determined analytically by means of a dampedunbalanced rotor response analysis and shall be confirmed by test-stand data.

2.9.1.5 An exciting frequency may be less than, equal to, or greater than the rotationalspeed of the rotor. Potential exciting frequencies considered in system design shallinclude, but are not limited to the following sources:

a. Unbalance in the rotor system.b. Oil-film instabilities (whirl).c. Internal nubs.d. Blade, vane, nozzle and diffuser passing frequencies.e. Gear-tooth meshing and side bands.f. Coupling misalignment.g. Loose rotor-system components.h. Hysteretic and friction whirl.i. Boundary-layer flow separation.j. Acoustic and aerodynamic cross-coupling forces.k. Asynchronous whirl.




Figure 3.13. Rotor Response Plot

2.9.1.6 Resonance of support systems within the vendor’s scope of supply shall notoccur within the specified operating speed range or the specified separationmargins, unless the resonances are critically damped.

2.9.1.7 The vendor who is specified to have unit responsibility shall determine thedrive-train critical speeds (rotor lateral, system torsional, blading modes and thelike) are compatible with the critical speeds of the machinery being supplied andthe combination is suitable for the specific operating speed range.





The location of the critical speed of a particular machine, in relation to its operatingspeed, is largely determined by the machine speed, size and bearing type. For a givenline of machines and rating, the parameters directly under the control of the rotor systemdesigner are limited.

For the Norwood range of machines, essentially all machines with four or morepoles (1800 RPM and below) have their critical speeds above operating speed. Two polemachines; however, may have the critical speed either above or below the operatingspeed of 3000 RPM or 3600 RPM (for 50 Hz or 60Hz power, respectively).

Separation margins between operating speed and critical or resonance speeds aresometimes specified by customers. According to API 541, resonant response peaks of themotor shall be at least 15% removed from operating speed.


Accessories


Table of ContentsGeneral............................................................................................................................................... 2Bearing Thermal Protective Devices ................................................................................................. 3 Resistance Temperature Detectors (RTD’s).......................................................................................... 3 Thermocouples (BTC’s)....................................................................................................................... 4 Thermometers ................................................................................................................................... 4 Temperature Relays ........................................................................................................................... 5Current Transformers ........................................................................................................................ 6 Self-Balancing Differential Protection ................................................................................................. 6 Zone Differential Protection ............................................................................................................... 7Differential Pressure Devices ............................................................................................................ 8 Differential Pressure Switch ............................................................................................................... 8 Manometer ........................................................................................................................................ 8Elastimold Quick Disconnects ........................................................................................................... 9Filters ............................................................................................................................................... 10Oil Sump Heaters ............................................................................................................................. 11Screens ............................................................................................................................................. 11Shaft Seals ....................................................................................................................................... 12Slide Rails ......................................................................................................................................... 12Space Heaters .................................................................................................................................. 13Stator Thermal Protective Devices .................................................................................................. 15 Resistance Temperature Detectors (RTD’s)........................................................................................ 15 Thermocouples (STC’s) ..................................................................................................................... 17 Thermostats .................................................................................................................................... 18 Thermistors ..................................................................................................................................... 19 Thermistor Control Module (for use with Thermistors) ..................................................................... 19Surge Protection .............................................................................................................................. 20Tachometers .................................................................................................................................... 21Vibration Detection Devices ............................................................................................................ 22 Shaft Sensing Devices ...................................................................................................................... 22 Bearing Housing Sensing Transducers .............................................................................................. 23 Velocity Pickups ............................................................................................................................ 23 Accelerometers ............................................................................................................................. 23 Vibration Detection Switches ........................................................................................................ 24Zero-Speed and Plugging Switches ................................................................................................. 25


Accessories


General

NOTE: A specific device manufacturer should not be specified unless it is absolutely the only oneacceptable for that application. The complete specification of the needed device without supplieridentification is the preferred specification arrangement. Supplier identification with thestatement "or equivalent" is the next preferred arrangement. The insistence on a specific supplierof a device can result in time delays since the item must be special ordered for that specificmotor. The devices supplied by different manufacturers are quite often non-interchangeable andthe motor may have to be redesigned to match the specified device. This can result in timedelays and additional costs.


Accessories


Bearing Thermal Protective Devices

Bearing temperature devices are used mainly in sleeve bearing motors; however, may beused with anti-friction bearings in certain applications. Consult factory for applications involvinganti-friction bearings.

NOTE: Depending upon specific requirements consult factory when more than one type ofbearing protective device is required on a motor and/or when provisions for external pressurelubrication is requested or required.

Resistance Temperature Detectors (RTD's)

The basic operation and types of bearing RTD's are similar to that of stator RTD's.

The standard bearing RTD is a tip sensitive device consisting of a probe with ahermetically sealed tip, inside of which is a resistance element, in the form of a coil. Theremainder of the assembly consists of a protective stainless steel sheath to which the probe isattached. The RTD leads are brought internally to a terminal block in an auxiliary terminal box.No additional insulation within sheathing is offered besides the insulation on the lead wire itself.

Also available are spring-loaded RTD’s with or without a weather tight connection head. Ifthe weather tight connection head is supplied, the RTD lead wires may either be field connectedat the head to a remotely located monitoring system or brought externally to a terminal block inan auxiliary terminal box mounted on the motor. Consult factory for pricing of this arrangementor forward specific requirements for review. When insulated bearings are specified, the bearingRTD's are also insulated.


Accessories



Thermocouples (BTC's)

The basic operation and types of bearing thermocouples are similar to statorthermocouples.

The standard bearing thermocouple is a tip sensitive device consisting of a probe, insideof which is the thermocouple, with the junction at the tip. The remainder of the assemblyconsists of a protective stainless steel sheath where the probe is attached. It is a four lead, dualelement, ungrounded, and non-spring-loaded thermocouple. The thermocouple leads arebrought internally to a terminal block in an auxiliary terminal box.

Also available are spring-loaded thermocouples, with or without a weather tightconnection head. If the weather tight connection head is supplied, the thermocouple lead wiresmay either be field connected at the head to a remotely located monitoring system or broughtexternally to a terminal block in an auxiliary terminal box mounted on the motor. Consult factoryfor pricing of this arrangement or forward specific requirements for review. When insulatedbearings are specified, the bearing thermocouples are also insulated.

If a particular type, manufacturer, or mechanical configuration (sheath material, spring-loaded, etc.) of bearing thermocouple is required please forward specific requirements to factoryfor review.

Thermometers

Dial-type indicating thermometers are used for direct reading of bearing temperatures.The standard dial thermometer is the United Electric Model T800 without alarm contacts. Itcomes with a bimetallic-type with back connection, stainless steel case, and has an operatingrange of 50°F to 300°F. Also available is United Electric Series 802 with alarm contacts, armorsleeves, and has an operating range of -20°C to +120°C.

If a particular type or manufacturer of thermometer is required please forward specificrequirements to factory for review.


Accessories



Temperature Relays

Bearing temperature relays (thermostats) are used to cause an alarm or trip a circuit toalert or guard against bearing failure. Both non-indicating and indicating types of bearingtemperature relays are available.

The standard relay is the United Electric Control Co., Model 802 non-indicating relay. Thethermal system of this device consists of a remote bulb, capillary, and bellows filled with atemperature sensitive liquid. The bulb is sensitive along its full length and is located to sense thebearing temperature. The liquid, and hence the bellows, expands with heat to actuate a snap-action switch at a pre-set temperature. The relay automatically resets when the temperaturedrops 10°C. The switch is pre-set at the factory to operate at 96°C +3°C.

Indicating type bearing temperature relays are also available. The principle of operation issimilar to that of the non-indicating relay except that the expansion of the bellows is used toactuate a direct reading, dial type, temperature indicator as well as the snap-action switch.

Both non-indicating and indicating relays are normally furnished with one set of contacts.Two contact relays (for alarm and shutdown) are also available. Consult factory for pricing orforward specific requirements for review.


Accessories


Current Transformers

Current transformers are used with metering, relaying, and control equipment whichcannot normally accommodate the relatively high line currents and voltages associated withlarge electric motors. Current transformers are used to provide currents of reduced valueproportional to the currents to be measured.

Standard current transformers are usually of the ring-type or window construction. Thistype of current transformer consists of a ring shaped steel core wound with copper wire. Themotor lead, which is the primary winding of a two winding transformer, passes through thecenter window of the current transformer. A current in this primary winding induces a current inthe secondary winding. One or more current transformers are used to monitor line currents inone or more phases. Current transformers are used in various ground fault differential protectionarrangements. The two most common arrangements are the self-balancing method and thezone method.

Self-Balancing Differential Protection

In the self-balancing method, three current transformers are used, one for each phase.The motor windings may be either Wye or Delta connected and both ends of each phase windingare brought out of the motor and passed through one of the current transformers. Theappropriate winding connection is then made within the main terminal box. Under normalconditions the currents in both leads are equal, but flowing in the opposite direction at anyparticular instant (opposite polarity). Since the voltages induced in the current transformerwinding by the lead currents are equal, the resulting induced voltage is zero; therefore zerocurrent flows in the secondary current transformer winding. Should a ground fault occur on themotor side of the current transformer, a flow of current from motor winding to ground will occurand the currents in both phase winding leads will no longer be equal. A resultant voltage will beinduced in the current transformer winding and a current will flow to activate the protectiveequipment. Current transformers used in the self-balancing differential protection arrangementusually have a 50:5 transformation ratio.


Accessories


Current Transformers

Zone Differential Protection

Current transformers may also be used in the zone differential protection arrangement.In this arrangement, only the normal internal ends of the phase windings are passed through thecurrent transformers mounted on the motor. The line currents are monitored by a second set ofidentical current transformers located elsewhere, usually at a panel board. In this arrangement,the full winding currents at both locations are compared. This arrangement will provide groundfault protection not only for the motor winding, but also for the main lead cable on the motorside of the panel board. Since the full value of the winding current is being measured, theirarrangement may require current transformers with transformation ratios of up to 800:5 orhigher. It should be noted, current transformers used in zone differential protectionarrangements must be short circuited during motor start up since they would otherwise bemeasuring full locked rotor currents.

Current transformers may be provided by either Siemens or the user and must bemounted in a special main conduit box. The line leads must be longer than standard and, if thecurrent transformers are to be used in a differential protection arrangement, the normallyinternal end of each phase winding must be brought out of the motor to the conduit box. Theleads of the current transformer windings are brought out of the main conduit box to a terminalblock in a special auxiliary terminal box mounted on the side of the main conduit box.

The self-balancing differential protection arrangement is the standard. If the zonearrangement or any other system is desired, details of such arrangements, including currenttransformer ratio and accuracy, should be forwarded to the factory for evaluation and pricing.


Accessories


Differential Pressure Devices

Differential Pressure Switch

For motors equipped with air filters, the use of a pressure differential device isrecommended to provide a warning of reduced airflow caused by clogged filters. When thedifferential pressure across the filter reaches a recommended limiting maximum value, filterreplacement or cleaning is indicated as necessary. The differential pressure switch consists oftwo pressure chambers separated by a sensitive diaphragm. One pressure chamber is connectedto the atmosphere and the other to the exhaust side of the filters. The spring-loaded diaphragmmoves when a change occurs in the differential pressure between its two sides, transmitting aforce to a snap-action switch. The switch is designed to actuate upon an increasing differentialpressure. The diaphragm motion is resisted by a calibrated spring. The spring determines therange of differential pressure within which the diaphragm motion will actuate an electric switch.Adjusting the compression or tension of the spring sets the actuation point. In this particularapplication, the differential pressure is the difference between atmospheric pressure and anegative air pressure within the motor enclosure. The switch is used to indicate a pressuredifferential across the filter and is connected to activate an alarm or control circuit provided bythe customer. Pressure differential switches are recommended when the permanent installationof a pressure differential device is required. The standard is a Dwyer Model No. 1950 explosion-proof pressure differential switch.

Manometer

The displacement of a liquid (oil, water, etc.) in a manometer tube may also be used tomeasure pressure difference across a filter. The simplest form of manometer utilizes the familiartransparent "U" shaped tube. When the ends of the liquid column in the "U" tube are exposed tounequal pressures, the difference in pressure is related to the difference between the heights ofthe fluid column in the two legs of the tube. The manometer is a measuring instrument and notan alarm device, as is the pressure differential switch.

It should be noted that a manometer is not recommended because of its relative fragilityand difficulty in reading. If this type of device is required please forward specific requirements tothe factory for review.


Accessories


Elastimold Quick Disconnects

Quick disconnect type connectors are used for easier installation and/or removal of amotor. A disconnect consists of two components, a connector and a bushing. Two types ofdisconnects, the 200 Amp Deadbreak and 600 Amp Deadbreak, are available as follows:

200 Amp Deadbreak: For 160 amp - 15 KV class system600 Amp Deadbreak: For 480 amp - 15 KV class system

For disconnects on motors with full load currents above 600 amps, refer to the factory. Ifthe customer uses one cable per phase, three disconnects are required; if two cables per phase,six disconnects are required. For the factory to properly size and purchase Elastimold(manufacturer) Quick Disconnects, the following information is required:

A) Cable size (solid or stranded conductors)

B) Insulation thickness (normal range 90-220 mils)

C) Type of cable shielding:(1) Metallic Tape(2) Metallic Drain Wires(3) Unishield(4) Lead(5) Nonshielded

D) Number of feeder cables per phase


Accessories


Filters

On the fundamental open motor, cooling ambient air enters into direct contact with themachine windings and can carry small-size dust particles into the machine interior. Electricallyconducting particles can be a hazard to winding insulation. Also, compacting of air-borne dirtinto the machine ventilating passages will impair ventilation and increase winding temperature.Equipping machine intake air passages with filters can minimize the entry of dirt particles. Thisremoves contaminating particles from the cooling air before entering the machine.

The standard filter is a permanent, dry, washable, high velocity, panel-type impingementfilter. The filter divides incoming air into small turbulent streams, and causes foreign particles tocollect on the wire mesh. As the dirt builds up from the entering side of the filters, airflow isdiverted to the cleaner mesh where the filtering action continues.

To guard against reduced airflow, through dirty or clogged filters, differential pressureswitches and/or thermal protection is optionally available. These devices are discussed elsewherein this section.

The standard filter consists of a galvanized steel screen medium. Stainless steel oraluminum media are also available options. Other filter media may also be obtained, but specificrequirements must be referred to the factory for pricing.

Filters are typically used on WPII enclosures. For ODP or WPI enclosures please forwardspecific requirements to the factory for review.


Accessories


Oil Sump Heaters

Immersion type oil sump heaters may be used on motors having oil lubricated bearingsto heat the bearing oil in applications where the ambient temperature may fall to 10°C (50°F) orbelow.

The customer must specify oil sump heaters. Oil sump heaters consist of a resistanceelement, (wires) embedded in a high-grade refractory material, having excellent heatconducting and electrical insulating characteristics. The heater is normally encased in a seamlesssteel tube or sheath. Furnished oil sump heaters are of the capsule immersion type and aremounted in a 0.5" NPT or 0.75" NPT hole on the side of the bearing housing.

Thermostatic control of oil sump heater operation is considered essential and is astandard feature with oil sump heaters. The thermostat is wired in series with the heaterelement and is used to sense the temperature of the oil. This device assures that the oil sumpheater is energized when required to maintain oil temperature at the appropriate level. Sumpheater leads and thermostat leads are brought to a special terminal box mounted on the bearinghousing. Oil sump heaters are available for all enclosures.

Optional stainless steel sheathing and special thread fittings are available. If specificmanufacturers or types are required, forward specific requirements to factory for review.

Screens

Screens can be provided on open drip-proof machines to meet the NEMA "guarded"definition and are furnished as standard on all WPI enclosures, 580 through 800 frames, and onall WPII enclosures. 500-frame WPI enclosures have cast openings in yoke sides and endhousings for airflow that are sized to meet the requirements of NEMA “guarded” definition.

Standard screen material is stainless steel with airway opening size 0.25-in. by 0.25-in,which complies with API 541 specifications.


Accessories


Shaft Seals

When motors are cycled on and off, the resultant heating and cooling effect may drawcontaminants from the surrounding area into the motor along the shaft extension. Thecontaminants would proceed to mix with the bearing lubricant, changing its properties, andresulting in damage to the bearing or significantly reducing the bearing life. A shaft seal can beutilized to minimize this contamination. A shaft seal is sometimes referred to as a shaft slinger orshaft flinger.

Anti-friction bearing motors are supplied with a rubber V-ring external shaft seal on allenclosures (except for SH560, SH630, SH710, which uses a steel external labyrinth shaft seal).The following list indicates the standard and available options for anti-friction bearing shaftseals. Refer to the factory for pricing on optional seals.

-Rubber Standard V-Ring Seal- Inpro® brand - Bronze-JM Clipper – Non-metallic composite

NOTE: All sleeve bearing motors are supplied with labyrinth-type shaft seals made of eitheraluminum or a non-metallic composite. Anodized aluminum shaft seals are available as anoption where aluminum is the standard. Refer to the factory for pricing.

Slide Rails

Slide rails are primarily motor bases that are used in the adjustment of the motor positionrelative to an external load. Slide rails are an option available for motors that are determined tobe suitable for belt drive applications.

The rails consist of fabricated structural steel with push-pull adjustment. Individualfootpads provide under-rail clearance, accommodate span mounting, and are often moreadaptable to uneven surfaces.

Slide rails are supplied in sets of two per motor and are shipped separately.


Accessories


Space Heaters

Space heaters are used to maintain motor internal air temperature above the dew pointduring periods of motor shutdown. In this way, water accumulation caused by moisturecondensation inside the motor is prevented. Space heaters are recommended for installations indamp locations and should be activated when the motor is de-energized. Space heater capacityis selected, depending upon the size and type of enclosure, to maintain the temperature withinthe motor approximately 5°C to 10°C above the ambient temperature. Four basic types of spaceheaters are currently in use. Type selection depends upon frame size and enclosure. See SpaceHeater Table 4.1.

Strip and tubular type heaters are available as non-standard alternates for motors thatuse flexible heaters as standard, with the exception of SH400-SH450-880 Frame CGZ. Whentubular heaters are used on 500-frame CZ motors the space available for stator windings andconnections is reduced. There will be a reduction in maximum available horsepower output. Theflexible space heater consists of a heating element enclosed within a silicone rubber jacket. Theheater is normally tied to the ends of the winding and conforms to the shape of the coil endsurface. Usually, one or more heaters are installed on each end of the motor winding.

The circular and semi-circular (banana) tubular space heaters consist of an inner heatingelement and an outer metallic protective enclosure or sheath. Brass, stainless steel, or air blackheat steel is generally used as the sheath material. These types of space heaters are mountedvertically between the bearing housing and coil end.

Strip heaters consist of a heating element enclosed within a rectangular bar shapedsheath. These heaters are available in various widths and lengths and are mounted on thebottom of yokes of open machines. Space heater arrangements are available for operation with115, 230, or 460 volts, single phase, power sources. The standard space heater data sheetincluded in this section indicates the total space heater wattage required for a particular typeand size enclosure. Individual space heaters are arranged in series or parallel depending uponthe supply voltage needed to obtain the desired total wattage.

Space heater leads will normally be terminated in the main conduit box of low voltage(600 volts and below) motors. For the Medallion line and higher voltage motors, an auxiliaryterminal box will be supplied for the termination of space heater leads. Space heater leads willnormally be terminated at a terminal block if an auxiliary terminal box is supplied.


Accessories


Space Heaters

Table 4.1. Standard Space Heaters

Frame Type VoltsHeaterType

QuantityTotalWatts

°C SurfaceTemp.

449/S449 1LA3, 1NS3 120/240 W 2 260 196

500/580All Except

CGZZ120/240 W 4 400

78 (135 at100°C a.)

680

CG, CGII 120/240 S 4 800 132

CAZ, CGG 120/240 S 4 500 108

SH400SH450

CGZ 120/240 W 4 600100 (160 at

100°C a.)

880 CGZ 120/240 W 4 800110 (160 at

100°C a.)

SH560 1LA4 120/240 W 4 800110 (160 at

100°C a.)

800

CG, CGII

120/240 S 8

1000 108

CAZ, CGG 720 86

680/800CGV

CGIIVCAZV

120/240 W 4 600100 (160 at

100°C a.)

SH630 All 120/240 T 2 1000100 (140 at

80°C a.)

SH710 All 120/240 T 2 1400130 (170 at

80°C a.)W = wrap around, S = strip type, T = tubular

Special arrangements are available for applications requiring lower than standardsheath temperatures. Consult the factory for pricing and availability.


Accessories


Stator Thermal Protective Devices

Thermal sensing devices are used to prevent possible damage to stator windings orbearings due to excessive temperatures. These various devices are classified into two principlecategories: monitoring detectors and relays or switches. Monitoring detectors quantitativelymeasure temperature levels. Relays and switches open or close a circuit upon reaching apredetermined temperature level.

Resistance Temperature Detectors (RTD'S)

A stator RTD consists of a resistance element of fine wire molded into a thin plastic stripthat is placed between coils in the stator slots. Normally, six RTD's, two per phase, are evenlyplaced around the stator.

The change in resistance of an RTD is proportional to temperature change. Consequently,these changes in resistance values, when fed into an external instrumentation system, mayenable any or all of the following functions to be performed:

• Activate an alarm signal.• Automatic or "demand log" printout of winding temperature via process computer.• Temperature read-out via panel meter or digital display.• Automatic shutdown.• Continuous trend chart recording.

Stator RTD's respond to temperature throughout the full length of wire element,consequently, they may be considered to measure average “hot spot” temperatures.Recommended alarm/shutdown temperatures can be found in Section 5.

RTD's having various resistances vs. temperature characteristics are available. The followingtypes of RTD’s are available and the particular type of RTD required must be specified;

• 10 OHMS at 25°C - copper• 100 OHMS at 0°C - platinum (DIN Standard 43760 (Class B precision) available onrequest)• 120 OHMS at 0°C - nickel


Accessories



Resistance Temperature Detectors (RTD'S) – cont.

In designing a temperature monitoring system, the possibility of lead wire compensationmust be considered. The measuring leg of the monitoring bridge contains not only the resistanceof the detector element but also the resistance of both lead wires connecting the detector to thebridge. These leads may be hundreds of feet long to reach a centrally located monitor serving anumber of detectors. Adding a third lead wire to the detector can permit automaticcompensation for lead wire variations by inserting equal lead wire resistance into both legs ofthe bridge. For this reason, three leads are furnished as standard.

Stator RTD's are Class H and use AWG 30 lead wire. Stator RTD leads are brought to astrip-type terminal block in an auxiliary terminal box.

Stator RTD's are available for all ratings manufactured at Norwood; however, the use ofRTD's with motors using random wound coils is not recommended. The shifting of individualconductors of a random wound coil during winding may involve sufficient force to damage theRTD element.

Other options for stator RTD’s are 4-lead wires and/or spiral armor cabling. Consult thefactory for pricing and availability. If a particular type or manufacturer is required, please forwardspecific requirements to the factory for review. For SH710 frame applications, consult thefactory.


Accessories



Thermocouples (STC'S)

A thermocouple is a temperature-sensing device consisting of two dissimilar metal wires.The wires are welded together at one end to form a measuring "point sensitive" junction that isused to sense the winding temperature. The circuit develops a small DC voltage, which isproportional to the temperature difference between the measuring junction and a referencejunction. In actual operation, the reference junction is an external monitoring system thatconverts the voltage developed by the thermocouple to a temperature value. Thermocouples arecapable of enabling the performance of functions similar to those for stator RTD's. As in the caseof stator RTD's, stator thermocouples are embedded between coils in the stator slots. Standardpractice is to provide six thermocouples, two per phase, evenly spaced around the stator.

The standard stator thermocouples consist of two wires of dissimilar metals weldedtogether. Thermocouple leads are a 20-gage thermocouple wire brought to a strip-type terminalblock in an auxiliary terminal box.

The following types of thermocouples are available and the particular type ofthermocouple required must be specified;

• Copper Constantan - ANSI Type T• Chromel Constantan - ANSI Type E• Chromel Alumel - ANSI Type K• Iron Constantan - ANSI Type J

Recommended alarm/shutdown temperatures are in Section 5. Stator thermocouples areavailable for all motors in all enclosures (consult the factory for SH710 frame motors).


Accessories



Thermostats

Thermostats use a snap-action, bi-metallic, disc-type switch to open or close a circuitupon reaching a pre-selected temperature. When heated to a predetermined temperature, thestresses in the disc cause it to reverse its curvature instantaneously. The action of the disc opensor closes a set of contacts in an energized control circuit. Thermostats are available with contactsfor normally open or normally closed operation, but the same device cannot be used for both.Thermostats are pre-calibrated by the manufacturer and are not adjustable. The discs arehermetically sealed and are placed on the stator coil end turns. The output of a thermostat caneither energize an alarm circuit, if normally open, or de-energize the motor contactor, ifnormally closed, and in series with the contactor. Since thermostats are located on the outersurface of the coil ends, they sense the temperature at that location. Thermostats are notconsidered suitable protection for stall or other rapidly changing temperature conditions.

Thermostat leads are normally brought to the main conduit box of low voltage (600 voltsand below) motors and to an auxiliary terminal box for higher voltage motors. The standardstator thermostat is a Texas Instrument Klixon.


Accessories



Thermistors

The thermistors used are positive temperature coefficient (PTC) sensors. They areembedded in the end turns of the winding. A set of sensors consists of three sensors, one perphase. The resistance of the sensor remains relatively low and constant over a wide temperatureband and increases abruptly at a pre-determined temperature or trip point. When this occurs,the sensor acts as a solid-state thermal switch and, when connected to a matched solid-stateelectronic switch in an enclosed control module, it de-energizes a pilot relay. The relay, in turn,opens the motors control circuit or the control coil of an external line break contactor to shutdown the protected equipment. When the winding temperature returns to a safe value, themodule permits manual reset.

A typical temperature sensing system consists of three thermistors and the optionalcontrol module. Sensor leads are normally brought to the main conduit box of low voltage (600volts and below) motors or to an auxiliary terminal box for higher voltage motors.

The standard stator thermistor is an Epcos Thermistor pellet with insulatingencapsulation. Thermistors are available for all motors in all enclosures (for SH710 frame consultthe factory).

Thermistor Control Module (for use with Thermistors)

The optional control module is unattached to the motor for installation at the locationdesired by the user. It should be noted that sensors are usually matched to a particular controlmodule, consequently, control modules by one manufacturer are not necessarily usable withsensors by another manufacturer. Please forward specific requirements to the factory for review.

The standard control modules are Siemens 3RN1 thermistor motor protection relays,screw-type connector.

Note: The positive temperature coefficient (PTC) thermistor system is considered fail safe, sincea broken sensor or sensor lead will result in an infinite resistance and develop a responseidentical to that of an elevated temperature, de-energizing the pilot relay.


Accessories


Surge Protection

Surge protection is recommended for machines exposed to high voltage surges causedby switching, line faults, or lightning. A high voltage surge may be thought of as a steeply risingvoltage wave traveling along the incoming line circuit. Lightning arrestors are used to protectthe ground wall insulation by reducing the magnitude of the voltage surge. Surge capacitors areused to protect the turn-to-turn insulation by reducing the slope of the wave front.

A complete surge protection unit consists of three station-type valve arrestors and,normally, a three-phase surge capacitor all mounted in a special, fabricated steel terminal box.The arrestors and surge capacitors are solidly grounded to the terminal box. All internalcomponents are factory mounted and wired. The terminal box is a separate freestanding boxand access is provided through a bolted-on, gasketed and hinged front cover.

Note: If no arrestors are required or supplied the front cover is not hinged. The conduitentrance is normally made through the bottom of the terminal box. Alternate entry is available,but forward specific requirements to the factory for review.


Accessories


Tachometers

A tachometer is an instrument used to measure or determine the rotational speed of ashaft. Their use on Norwood size motors is primarily for adjustable frequency drive applications.The tachometer is an electromechanical device called a rotary pulse generator and is used as afeedback device for the AC adjustable frequency drive control system.

The standard tachometer for antifriction bearing motors has a single output (dual isoptional) and 1024 pulses per revolution (PPR). Depending upon the motor enclosure andbearing arrangement, either a throughput-type or a coupled single shaft tachometer is utilized.Refer to the factory for tachometer selection, pricing, and availability.

Other types are available, but please forward specific requirements to the factory for review.


Accessories


Vibration Detection Devices

Shaft Sensing Devices

Vibration may be identified in terms of peak-to-peak displacement, peak velocity orpeak acceleration. At a known frequency, a mathematical relationship exists between the threeparameters and a measurement of any one of the three will permit the determination of theother two. Detection devices are available to measure any of the three parameters.

Amplitude sensing devices, for measuring vibration at a shaft are, called proximityprobes, eddy probes, or non-contact pickups. They are eddy-current devices that measuredistance and change in distance. The probe is mounted in close proximity to the shaft with atypical gap of 50 mils between probe tip and shaft surface. The probe radiates a magnetic fieldthat varies in strength as the gap varies. By measuring the field strength, the distance betweenprobe tip and shaft surface can be determined.

The signal produced by the probe is quite small; consequently, probes are used with asmall electronic package called a proximitor (also called an oscillator-demodulator, driver orsignal sensor). The signal produced by the probe and amplified by the proximitor is thentransmitted to remotely located monitoring equipment. The probe and proximitor are connectedwith a co-axial cable having a definite length and impedance. Any change in length of the cablewill affect the calibration of the system. An external DC power source is required to drive theprobe and proximitor.

Proximity probes are used to measure either radial or axial displacement. In a typicalapplication for the measurement of radial displacement, two probes are mounted near thebearing at a 90° angle to each other (X-Y configuration) to measure shaft movement in bothdirections. The portion of the shaft observed by the probe has a burnished finish and anonmagnetic epoxy coating is applied. There can be no plating material on that portion of theshaft. In an axial or thrust monitoring application, proximity probes are used to measure shaftdisplacement in an axial direction. One or more probes are mounted in such a position as tosense the location of the surface of the shaft end or a thrust collar, if available.

A single proximity probe may be used in a key phasor application to provide a referencein time and position for data acquired by displacement probes mounted elsewhere. In thisapplication, a probe is mounted radially to observe the shaft keyway and provide a voltage pulseoccurring once every revolution when the shaft is in a known position. The standard transducersystem consists of Bentley Nevada 3300 series probes with aluminum probe heads, proximitorswith aluminum explosion-proof housings, and cable. Optionally, stainless steel probe heads andproximitor housing can be supplied, but consult factory for pricing. If other manufacturer’s typesare requested or required please forward specific requirements to the factory for review.


Accessories



Bearing Housing Sensing Transducers

1. Velocity Pickups

A velocity pickup consists of a fixed case, which is surface mounted directly to a pad onthe motor. Inside the case, the movement of a spring loaded seismic mass and attached coil ofwire through a permanent magnet field produce an induced voltage. The high level signalgenerated by this motion is directly proportional to the absolute vibratory velocity at the point ofattachment. Being self-generating, velocity pickups require no external power source. Theirrelatively high output and low source impedance allow velocity pickups to provide a signaldirectly to remotely located monitoring equipment without the need for pre-amplificationequipment. Velocity pickups are seismic devices since they measure total vibration relative to afixed point in space.

NOTE: If this type of device is required please forward specific requirements to thefactory for review.

2. Accelerometers

An accelerometer consists of a fixed case, which is surface mounted directly to a pad onthe machine. The case contains a seismic mass in contact with a quartz crystal. The outputvoltage of the crystal is proportional to the force applied by the mass. In operation, the crystal issubjected to a varying force "F" (result of force equals mass times acceleration) and develops avoltage that is proportional to acceleration and the crystal constant. Usually, the output ofaccelerometers is quite small and they must be used with pre-amplifiers or "charge" amplifiers inorder to provide a signal suitable for transmission to the monitoring equipment. The chargeamplifier may be miniaturized and installed within the accelerometer case or furnishedseparately for external mounting. Typically, accelerometers require an external DC power source.Accelerometers are particularly responsive to higher frequency vibration levels. Accelerometersmay be considered seismic devices since they measure total vibration, relative to a fixed point inspace.

NOTE: If this type of device is required please forward specific requirements to thefactory for review.


Accessories



3. Vibration Detection Switches

The vibration detector switch is an acceleration sensitive device, which is pad mounteddirectly on the motor. The switch measures the total acceleratory shock perpendicular to thebase of the switch at the mounting point.

When the entire assembly is subjected to vibration perpendicular to the base, the peakacceleration times of the effective mass of the arm produce an inertial force that, aided by theadjustable spring, tends to pull the arm away from the restraining force of the magnet andactuate the switch. When the peak acceleration exceeds the set-point level, as determined by theforce of the adjusting spring, the arm moves to close the switch contacts and actuate the device.Depressing a manual reset button may reset the switch or by energizing an electric reset coil.The switch provided is normally furnished with single pole, double throw, load contacts andreset coils. The set point of the switch is field adjustable. An external AC power source isrequired. The vibration switch provides detection of excessive vibration caused by malfunctionssuch as faulty bearings or a bent shaft. When excessive vibration is present, the destructiveforces are a function of both the amplitude of displacement and frequency. An accelerationdevice is responsive to both amplitude and frequency, and therefore, provides excellentprotection for the machine. The switch may be used to actuate an alarm or cause a shutdown.

The standard vibration detection switch provided is the Robert Shaw Model 375A or376A Vibraswitch®. Various other vibration switches are available to provide special features,depending upon customer requirements, such as dual switch contacts providing separate alarmand shutdown set points, startup trip delays, and solid-state switches.

Please forward specific requirements to the factory for review.


Accessories


Zero-Speed And Plugging Switches

The Allen-Bradley Bulletin 808 Speed Switch is available for horizontal, anti-frictionbearing motors. It is used to provide plugging or anti-plugging of squirrel cage motors inconjunction with automatic starters arranged for reversing or plugging duty. It may also be usedas a speed switch or “zero-speed” switch. The 808 switch is an electromagnetic device thatemploys the use of a disc shaped permanent magnet mounted on the switch shaft that rotatesinside of a copper cup. Although the cup is free to turn, an opposing spring force restrictsmovement. An operating arm is mounted on the face of the cup to actuate either of twocontacts located on each side of the arm. When the switch shaft rotates, a torque is developed inproportion to shaft speed that tends to cause the cup to move in the direction of shaft rotation.As the shaft speed increases from standstill, this rotational torque increases. When the torque issufficient to overcome the opposing spring force, the actuating arm activates one of thecontacts, depending upon the direction of rotation. Only one set of contacts is provided for eachdirection of rotation. In plugging operations, the forward or reverse contact is closed dependingupon the direction of rotation at any point above the point at which the contact is set to operate.As the shaft speed is reduced, the torque holding the contact closed is also reduced until a pointis reached at which the contact returns to the normally open position.

The speed at which the contacts will operate is easily adjusted by means of two externaladjustment screws, one for each set of contacts. After the switch has reached its normaloperating temperature, the screw is turned to adjust the point at which the contacts are tooperate.

The 808 speed switch is available in three contact operating speed ranges, 15-60 RPM,50-200 RPM and 150-900 RPM. The maximum shaft operating speeds are 1200 RPM for contactsoperating in the 15-60 RPM range and 1800 RPM for the 50-200 RPM and 150-900 RPM ranges.

The switch is mounted on a base attached to the non-drive end bearing housing of themotor and the switch shaft is normally direct coupled, using a flexible coupling, to a stub shaftthat extends from the non-drive end of the motor shaft. For maximum accuracy, the switchshould be driven at the highest available speed within its maximum operating range. Thecoupling arrangement between the switch and motor must be positive to avoid slippage.

In plugging applications, the switch automatically interrupts reverse braking power, asthe motor approaches zero speed. The speed at which the switch contacts operate is easilyadjusted so as to avoid coasting or reverse rotation. Contacts are normally open and arranged forplugging in one or both directions. In anti-plugging applications, the switch is used to applyreverse power when a selected safe speed is reached. In an anti-plugging application, thecontacts are normally closed and arranged for anti-plugging in either direction.


Accessories


Zero-Speed And Plugging Switches

As a speed-sensing switch, the switch may be used to sequence conveyors where it isessential for one conveyor to be running at nearly full speed before a second conveyor is started.It should be noted that although the switch has two sets of contacts, only one set is usable foreach direction of rotation.

In some applications, an accidental turn of the shaft may close the switch contacts andstart the motor. To guard against this possibility, the switch may be furnished with a lockoutsolenoid that mechanically prevents the contacts from operating unless the lockout coil isenergized. This feature is special and must be specified. The 808 switch is furnished in NEMA1,4, 7, 9 or 13 enclosures.

If the switch is directly coupled, as recommended, to the accessible non-drive end of themotor shaft, no more than one switch can be installed on a motor. If not directly coupled, butconnected through gears and a chain or timing belt, more than one switch may be installed on amotor. The use of the speed switch is limited to horizontal, anti-friction bearing motors. Theswitch cannot be used with sleeve bearing motors because of the thrust involved if directconnected and end-float produced alignment problems, if belt or chain connected.


Standards


Table of ContentsNational Electrical Manufacturers Association (NEMA) ................................................................... 2 NEMA Standard Publication MG 1-2016 ............................................................................................. 2American National Standards Institute (ANSI) ................................................................................. 4The Institute of Electrical and Electronics Engineers (IEEE) ............................................................. 5American Petroleum Institute (API) .................................................................................................. 6 API Standard 541, 4th Edition June 2004, 5th Edition December 2014 ................................................. 6 API Standard 547, 1st Edition January 2005, 2nd Edition May 2017 ..................................................... 7National Electrical Code (NEC) .......................................................................................................... 8 Class I Locations ................................................................................................................................. 9 Class II Locations .............................................................................................................................. 12 Class III Locations ............................................................................................................................. 13 500.6 Material Groups ..................................................................................................................... 14 500.8 Equipment ............................................................................................................................. 17 501.125 Motors and Generators, Class I / Divisions 1 and 2 .............................................................. 22 502.125 Motors and Generators, Class II / Divisions 1 and 2 ............................................................. 24 503.125 Motors and Generators, Class III / Divisions 1 and 2 ............................................................ 25 505.5 Classifications of Locations .................................................................................................... 26 505.8 Protection Techniques ........................................................................................................... 28Canadian Standards Association (CSA) ........................................................................................... 31 Horizontal Motors for Ordinary Locations ......................................................................................... 31 Vertical Motors for Ordinary Locations ............................................................................................. 32 Accessories ...................................................................................................................................... 32 Special Markings .............................................................................................................................. 32 Hazardous Location Motors.............................................................................................................. 32 Testing ............................................................................................................................................ 33


Standards


National Electrical Manufacturers Association (NEMA)

NEMA Standard Publication MG 1-2016

This standard provides information concerning performance, test, construction andmanufacturing of alternating-current and direct current motors and generators within theproduct scopes outlined in the applicable sections.

MG 1 is divided in the following way:

Section I - General Standards Applying to all MachinesPart 1 - Referenced Standards and DefinitionsPart 2 - Terminal MarkingsPart 3 - High-Potential TestsPart 4 - Dimensions, Tolerances, and MountingPart 5 – Rotating Electrical Machines - Classification of Degrees of Protection Provided byEnclosures for Rotating MachinesPart 6 - Rotating Electrical Machines - Methods of Cooling (IC Code)Part 7 - Mechanical Vibration – Measurement, Evaluation and LimitsPart 9 – Rotating Electrical Machines - Sound Power Limits and Measurement Procedures

Section II– Small (Fractional) and Medium (Integral) MachinesThe standards in this part cover AC motors up to and including the ratings built in frames

corresponding to the continuous open-type ratings given below:

Table 5.1. Motor RatingsSynchronous Speed HP

3600 5001800 5001200 350900 250720 200600 150514 125

Part 10 – Ratings - AC Small and Medium MotorsPart 10 – Ratings - DC Small and Medium MachinesPart 12 - Tests and Performance - AC and DC MotorsPart 12 - Tests and Performance - AC MotorsPart 12 - Tests and Performance - DC Small and Medium Motors


Standards


National Electrical Manufacturers Association (NEMA)

NEMA Standard Publication MG 1-2016 – cont.

Part 13 – Frame Assignments for Alternating Current Integral Horsepower InductionMotors

Part 14 – Application Data – AC and DC Small And Medium MachinesPart 14 – Application Data – AC Small And Medium MotorsPart 14 – Application Data – DC Small And Medium MotorsPart 15 – DC GeneratorsPart 18 – Definite Purpose Machines

Section III- Large MachinesThe standards in this part cover induction motors built in frames larger than those required

for ratings listed in Part 10.

Part 20 - Large Machines – Induction MachinesPart 21 – Large Machines – Synchronous MotorsPart 23 – Large machines – DC Motors Larger Than 1.25 HP per RPMPart 24 – Large Machines – DC Generators Larger Than 1 kW

Section IV- Performance Standards Applying to All Machines

Part 30 – Application Considerations for Constant Speed MotorsPart 31 – Definite Purpose Inverter-fed Polyphase MotorsPart 32 – Synchronous GeneratorsPart 33 – Definite Purpose Synchronous Generators for Set Applications

This is a safety standard for construction and a guide for selection, installation and use ofelectric motors and generators. The motors manufactured at the Norwood Plant of the IndustrialProducts Division are designed and manufactured using applicable NEMA Standards as minimumcriteria.


Standards


American National Standards Institute – ANSI

C50.41 - 2000 Polyphase Induction Motors for Power Generating Stations

The requirements in this standard apply to 60 Hertz polyphase induction motors intended for usein power generation stations, including the following:

1. Frame sizes larger than NEMA 4402. Squirrel-cage type3. Single speed or multi-speed4. Horizontal or vertical construction5. Form wound

Table 5.2. Temperature RiseMotor Part Method of

TemperatureDetermination

1.0 ServiceFactor

1.15 ServiceFactor

Insulated Windings (a) All HP Ratings Resistance 80°C 90°C (b) 1500 HP and less Embedded Detector 90°C 100°C (c) More than 1500 HP

(1) 7000 Volts and less (2) More than 7000 Volts

Embedded DetectorEmbedded Detector

85°C80°C

95°C90°C

The temperatures attained by cores, squirrel-cage windings, and mechanical partsshall not injure the insulation or the motor in any respect.

Note: The table above applies to a particular motor rating (that is, a 1.0 or 1.15 SF), and it is not intendedor implied that this information be applied as a dual rating to an individual motor.

Motors equipped with embedded detectors shall use them to demonstrate conformity withthis standard.

Excluded from the scope of this standard are:1. Additional specific features that may be required for application in nuclear-fueled power

generation stations.2. Additional specific features required in motors for use in locations involving hazardous

(classified) locations.3. Starting motors for reversible synchronous generator/motor units for pumped storage

installations.4. Wound-rotor motors.This standard is listed for reference only. Many of the technical requirements of this

standard have been included in NEMA MG 1 – 2016, Part 20.


Standards


The Institute of Electrical and Electronics Engineers (IEEE)

The following IEEE Standards may be used in specifying motors manufactured at theNorwood Plant.

IEEE 85-1973 (Reaffirmed 1986): Test Procedures for Airborne Sound Measurements onRotating Electric Machinery.

This test procedure defines approved methods for conducting tests and reporting resultsto affect the uniform determination of rotating electric machine sound under steady-stateconditions with an accuracy of +3dB.

IEEE 112-2004: Test Procedures for Poly-phase Induction Motors and Generators.This standard covers instructions for the conducting and reporting the more generally

applicable and acceptable tests to determine the performance characteristics of poly-phaseinduction motors and generators.

IEEE 841-2009: Standard for Petroleum and Chemical IndustriesThis standard’s purpose is to define mechanical and electrical performance, electrical

insulation systems, corrosion protection, and electrical and mechanical testing for severe dutyTEFC squirrel cage poly-phase induction motors for the petroleum and chemical industryapplications.Scope

§ Severe duty applications§ Up to and including 500 HP§ 200 – 4000 V§ 2 – 8 poles§ TEFC enclosures§ Anti-friction bearings§ IP55 degree of protection§ -25 to 40°C ambient & maximum altitude of 1000 m§ Cast iron frame and end shields


Standards


American Petroleum Institute (API)

API Standard 541, 4th Edition June 2004, 5th Edition December 2014

API 541 is a standard by which motors for critical services are defined and purchasedusing data sheets by which the purchaser may specify unique project requirements utilizingNEMA or IEC, and US customary or metric units. This standard improves reliability and service-ability.

Scope§ Petroleum industry service with one or more of the following characteristics:

§ Critical services§ Above 3000 HP (4-pole & lower speeds)§ >= 800 HP 2-pole totally enclosed motors§ >= 1250 HP 2-pole WPI & WPII motors§ >= 500 HP for vertically mounted motors§ Use in Class 1 Division 2 or Zone 2 locations§ Drives High inertia loads§ Motors using an adjustable speed drive as a source of power§ Motors used as induction generators§ “Abnormally hostile environments”.

Table 5.3. General Scope of APISIEMENS

Standard Ratings (HP) # Poles Enclosures ANEMA FramesAPI 547 1st Ed. -2005

250 - 3000 4 - 8 WPII & TEFC 500 – SH710< 800 2 TEFC 500 – 580

<1250 2 WPII 500 – 580API 541 4/5th Ed. –2004/2014

> 3000 4 - 8 All 680 – SH710>= 800 2 Enclosed 580 – SH710

>= 1250 2 WPI & WPII 580 – SH710

>= 500 All All Verticals 500 – SH710


Standards


American Petroleum Institute (API)

API Standard 547, 1st Edition January 2005, 2nd Edition May 2017

API 547 provides a general-purpose specification for motors in non-critical, petroleumand chemical applications, a definition of usual service conditions for motors under thisstandard, and a standard that recognizes two different systems of standards (NEMA and IEC).

On January 31, 2011, Siemens Industry’s Norwood motor manufacturing plant wascertified by the American Petroleum Institute to use the Official API 547 Monogram. In additionto the API Monogram, Siemens Quality Management System was also assessed by API, andfound to be in conformance with API Specification Q1 and ISO/TS 29001 for the design andmanufacture of electric motors.

Scope§ General-purpose petroleum, chemical and other industrial severe duty applications

§ 250 hp – 3000 hp (4 – 8 pole speeds) WPII & TEFC enclosures− < 800 hp for 2-pole motors of TEFC enclosures− < 1250 hp for 2-pole motors of WPII enclosures

§ 2300 – 13,200 V§ Driving centrifugal loads within inertia values of NEMA MG 1 Part 20

These standards, together with Appendix A (motor data sheets) and the specific jobspecification, cover the requirements for form wound, squirrel cage induction motors 250 HPand larger for use in petroleum industry services.API 547 also covers the induction motor, general purpose form wound 250 HP andlarger.


Standards


National Electrical Code (NEC)

NFPA 70-2017 NATIONAL ELECTRICAL CODE (NEC) The National Electrical Code ispublished by the National Fire Protection Association. The NEC is the major electrical safetystandard in the United States and many of the requirements such as terminal box size,grounding, spacing and the like have been incorporated into the NEMA standards we use.Wiring methods are included in chapters two and three.

Chapter five of the NEC covers the requirements for electrical equipment and wiring forall voltages in locations where fire or explosion hazards may exist due to flammable gases orvapors, flammable liquids, combustible dust, or ignitable fibers or filings. Articles 500 through505 contain most of the specific information needed for the design and application of motors inthese areas. Much of the following information is directly from the NEC however the definitionsbelow should be used only as a general reference. Consult the NFPA 70-2017 document for thecomplete descriptions.


Standards



Class I Locations

(B) Class I Locations. Class I locations are those in which flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors are or may be present in the air inquantities sufficient to produce explosive or ignitable mixtures. Class I locations shall includethose specified in 500.5 (B)(1) and (B)(2).

(1) Class I, Division 1. A Class I, Division l location is a location:

(1) In which ignitable concentrations of flammable gases, flammable liquid-producedvapors, or combustible liquid-produced vapors can exist under normal operating conditions, or

(2) In which ignitable concentrations of such flammable gases, flammable liquid-produced vapors, or combustible liquids above their flash points may exist frequently because ofrepair or maintenance operations or because of leakage, or

(3) In which breakdown or faulty operation of equipment or processes might releaseignitable concentrations of flammable gases, flammable liquid-produced vapors, or combustibleliquid-produced vapors and might also cause simultaneous failure of electrical equipment in sucha way as to directly cause the electrical equipment to become a source of ignition

Informational Note No. 1: This classification usually includes the following locations:

(1) Where volatile flammable liquids or liquefied flammable gases are transferred from onecontainer to another

(2) Interiors of spray booths and areas in the vicinity of spraying and painting operationswhere volatile flammable solvents are used

(3) Locations containing open tanks or vats of volatile flammable liquids

(4) Drying rooms or compartments for the evaporation of flammable solvents

(5) Locations containing fat- and oil-extraction equipment using volatile flammable solvents

(6) Portions of cleaning and dyeing plants where flammable liquids are used

(7) Gas generator rooms and other portions of gas manufacturing plants where flammablegas may escape

(8) Inadequately ventilated pump rooms for flammable gas or for volatile flammable liquids


Standards



Class I Locations – cont.

(9) The interiors of refrigerators and freezers in which volatile flammable materials arestored in open, lightly stoppered, or easily ruptured containers

(10) All other locations where ignitable concentrations of flammable vapors or gases arelikely to occur in the course of normal operations

Informational Note No. 2: In some Division I locations, ignitable concentrations of flammablegases or vapors may be present continuously or for long periods of time. Examples include thefollowing:

(1) The inside of inadequately vented enclosures containing instruments normally ventingflammable gases or vapors to the interior of the enclosure

(2) The inside of vented tanks containing volatile flammable liquids

(3) The area between the inner and outer roof sections of a floating roof tank containingvolatile flammable fluids

(4) Inadequately ventilated areas within spraying or coating operations using volatileflammable fluids

(5) The interior of an exhaust duct that is used to vent ignitable Concentrations of gases orvapors

Experience has demonstrated the prudence of avoiding the installation of instrumentationor other electrical equipment in these particular areas altogether or where it cannot be avoidedbecause it is essential to the process and other locations are not feasible (see 500.5 (A),Informational Note) using electrical equipment or instrumentation approved for the specificapplication or consisting of intrinsically safe systems as described in Article 504.

(2) Class I, Division 2. A Class I, Division 2 location is a location:

(l) in which volatile flammable gases, flammable liquid produced vapors, or combustibleliquid-produced vapors are handled, processed, or used, but in which the liquids, vapors, orgases will normally be confined within closed containers or closed systems from which they canescape only in case of accidental rupture or breakdown of such Containers or systems or in caseof abnormal operation of equipment, or

(2) In which ignitible concentrations of flammable gases, flammable liquid-producedvapors, or combustible liquid-produced vapors are normally prevented by positive mechanicalventilation and which might become hazardous through failure or abnormal operation of theventilating equipment, or


Standards



Class I Locations – cont.

(3) That is adjacent to a Class I, Division 1 location, and to which ignitible concentrationsof flammable gases, flammable liquid-produced vapors, or combustible liquid produced vaporsabove their flash points might occasionally be communicated unless such Communication isprevented by adequate positive-pressure ventilation from a source of clean air and effectivesafeguards against ventilation failure are provided.

Informational Note No. 1: This classification usually includes locations where volatile flammableliquids or flammable gases or vapors are used but that, in the judgment of the authority havingjurisdiction, would become hazardous only in case of an accident or of some unusual operatingcondition. The quantity of flammable material that might escape in case of accident, theadequacy of ventilating equipment, the total area involved, and the record of the industry orbusiness with respect to explosions or fires are all factors that merit consideration in determiningthe classification and extent of each location.

Informational Note No. 2: Piping without valves, checks, meters, and similar devices would notordinarily introduce a hazardous condition even though used for flammable liquids or gases.Depending on factors such as the quantity and size of the containers and ventilation, locationsused for the storage of flammable liquids or liquefied or compressed gases in sealed containersmay be considered either hazardous (classified) or unclassified locations. See NFPA 30-2015,Flammable and Combustible Liquids Code, and NFPA 58-2014, Liquefied Petroleum Gas Code.


Standards



Class II Locations

(C) Class II locations are those that are hazardous because of the presence of combustible dust.Class II locations shall include those specified in 500.5(C) (1) and (C) (2).

(1) Class II, Division 1. A Class II, Division l location is a location:

(l) In which combustible dust is in the air under normal operating Conditions in quantitiessufficient to produce explosive or ignitable mixtures, or

(2) Where mechanical failure or abnormal operation of machinery or equipment mightcause such explosive or ignitable mixtures to be produced, and might also provide a source ofignition through simultaneous failure of electrical equipment, through operation of protectiondevices, or from other causes, or

(3) In which Group E combustible dusts may be present in quantities sufficient to behazardous.

Informational Note: Dusts containing magnesium or aluminum are particularly hazardous, andthe use of extreme precaution is necessary to avoid ignition and explosion.

(2) Class II, Division 2. A Class II, Division 2 location is a location

(1) In which combustible dust due to abnormal operations may be present in the air inquantities sufficient to produce explosive or ignitable mixtures; or

(2) Where combustible dust accumulations are present but are normally insufficient tointerfere with the normal operation of electrical equipment or other apparatus, but could as aresult of infrequent malfunctioning of handling or processing equipment become suspended inthe air; or

(3) In which combustible dust accumulations on, in, or in the vicinity of the electricalequipment could be sufficient to interfere with the safe dissipation of heat from electricalequipment, or could be ignitable by abnormal operation or failure of electrical equipment.

Informational Note No. 1: The quantity of combustible dust that may be present and theadequacy of dust removal systems are factors that merit consideration in determining theclassification and may result in an unclassified area.

Informational Note No. 2: Where products such as seed are handled in a manner that produceslow quantities of dust, the amount of dust deposited may not warrant classification.


Standards



Class III Locations

(D) Class III Locations. Class III locations are those that are hazardous because of the presenceof easily ignitable fibers or where materials producing combustible flyings are handled,manufactured, or used, but in which such fibers/flyings are not likely to be in suspension in theair in quantities sufficient to produce ignitable mixtures. Class III locations shall include thosespecified in 500.5 (D) (l) and (D) (2).

(1) Class III, Division 1. A Class III, Division l location is a location in which easily ignitablefibers/flyings are handled, manufactured, or used.

Informational Note No. 1: Such locations usually include some parts of rayon, cotton, and othertextile mills; combustible fibers/flyings manufacturing and processing plants; Cotton gins andcotton-seed mills; flax-processing plants; clothing manufacturing plants; woodworking plants;and establishments and industries involving similar hazardous processes or Conditions.

Informational Note No. 2: Easily ignitable fibers/flyings include rayon, cotton (including cottonlinters and cotton waste), sisal or henequen, istle, jute, hemp, tow, cocoa fiber, oakum, baledwaste kapok, Spanish moss, excelsior, and other materials of similar nature.

(2) Class III, Division 2. A Class III, Division 2 location is a location in which easily ignitablefibers/flyings are stored or handled Other than in the process of manufacture.


Standards



500.6 Material Groups

For purposes of testing, approval, and area classification, various air mixtures (notoxygen-enriched) shall be grouped in accordance with 500.6(A) and (B).

Exception. Equipment identified for a specific gas, vapor, dust, or fiber/ flying.

Informational Note: This grouping is based on the characteristics of the materials. Facilities areavailable for testing and identifying equipment for use in the various atmospheric groups.

(A) Class I Group Classifications. Class I groups shall be according to 500.6(A)(1) through(A)(4).

Informational Note No. 1: Informational Note Nos. 2 and 3 apply to 500.6(A).

Informational Note No. 2: The explosion characteristics of air mixtures of gases or vapors varywith the specific material involved. For Class I locations, Groups A, B, C, and D, the classificationinvolves determinations of maximum explosion pressure and maximum safe clearance betweenparts of a clamped joint in an enclosure. It is necessary; therefore, that equipment be identifiednot only for class but also for the specific group of the gas or vapor that will be present.

Informational Note No. 3: Certain chemical atmospheres may have characteristics that requiresafeguards beyond those required for any of the Class I groups. Carbon disulfide is one of thesechemicals because of its low auto ignition temperature (90°C) and the small joint clearancepermitted to arrest its flame.

(1) Group A. Acetylene.

(2) Group B. Flammable gas, flammable liquid-produced vapor, or combustible liquid-producedvapor mixed with air that may burn or explode, having either a maximum experimental safe gap(MESG) value less than or equal to 0.45 mm or a minimum igniting current ratio (MIC ratio) lessthan or equal to 0.40.

Informational Note: A typical Class I, Group B material is hydrogen.

Exception No. 1: Group D equipment shall be permitted to be used for atmospheres containingbutadiene, provided all conduit runs into explosion proof equipment are provided withexplosion proof seals installed within 450 mm (18 in.) of the enclosure.


Standards



500.6 Material Groups – cont.

Exception No. 2: Group C equipment shall be permitted to be used for atmospheres containingallylglycidyl ether, n-butyl glycidyl ether, ethylene oxide, propylene oxide, and acrolein,provided all conduit runs into explosion proof equipment are provided with explosion proofseals installed within 450 mm (18 in.) of the enclosure.

(3) Group C. Flammable gas, flammable liquid-produced vapor, or combustible liquid-producedvapor mixed with air that may burn or explode, having either a maximum experimental safe gap(MESG) value greater than 0.45 mm and less than or equal to 0.75 mm, or a minimum ignitingcurrent ratio (MIC ratio) greater than 0.40 and less than or equal to 0.80.

Informational Note: A typical Class I, Group C material is ethylene

(4) Group D. Flammable gas, flammable liquid-produced vapor, or combustible liquid-producedvapor mixed with air that may burn or explode, having either a maximum experimental safe gap(MESG) value greater than 0.75 mm or a minimum igniting Current (MIC) ratio greater than0.80.

Informational Note No. 1: A typical Class I, Group D material is propane.

Informational Note No. 2: For classification of areas involving ammonia atmospheres, seeANSI/ASHRAE 15-2013, Safety Standard for Refrigeration Systems.

(B) Class II Group Classifications. Class II groups shall be in accordance with 500.6(B)(1)through (B)(3).

(1) Group E. Atmospheres containing combustible metal dusts, including aluminum,magnesium, and their commercial alloys, or other combustible dusts whose particle size,abrasiveness, and conductivity present similar hazards in the use of electrical equipment.

Informational Note: Certain metal dusts may have characteristics that require Safeguardsbeyond those required for atmospheres containing the dusts of aluminum, magnesium, andtheir commercial alloys. For example, zirconium, thorium, and uranium dusts have extremelylow ignition temperatures as low as 20°C (68°F) and minimum ignition energies lower than anymaterial classified in any of the Class I or Class II groups.


Standards



500.6 Material Groups – cont.

(2) Group F. Atmospheres containing combustible carbonaceous dusts that have more than 8percent total entrapped volatiles (see ASTM D3175-11, Standard Test Method for Volatile Matterin the Analysis Sample for Coal and Coke, for coal and coke dusts) or that have been sensitizedby other materials so that they present an explosion hazard. Coal, carbon black, charcoal, andcoke dusts are examples of carbonaceous dusts.

Informational Note: Testing of specific dust samples, following established ASTM testingprocedures is a method used to identify the combustibility of a specific dust and the need toclassify those locations containing that material as Group F.

(3) Group G. Atmospheres containing combustible dusts not included in Group E or Group F,including flour, grain, Wood, plastic, and chemicals.

Informational Note No. 1: For additional information on group classification of Class IImaterials, see NFPA 499-2013, Recommended Practice for the Classification of CombustibleDusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical ProcessAreas.

Informational Note No. 2: The explosion characteristics of air mixtures of dust vary with thematerials involved. For Class II locations, Groups E, F, and G, the classification involves thetightness of the joints of assembly and shaft openings to prevent the entrance of dust in thedust-ignition proof enclosure, the blanketing effect of layers of dust on the equipment that maycause overheating, and the ignition temperature of the dust. It is necessary; therefore, thatequipment be identified not only for the class but also for the specific group of dust that will bepresent.

Informational Note No. 3: Certain dusts may require additional precautions due to chemicalphenomena that can result in the generation of ignitable gases. See ANSI/IEEE C2-2012, NationalElectrical Safety Code, Section 127A, Coal Handling Areas.


Standards



500.8 Equipment

Articles 500 through 504 require equipment construction and installation that ensureSafe performance under conditions of proper use and maintenance.

Informational Note No. 1: It is important that inspection authorities and users exercise morethan ordinary care with regard to installation and maintenance.

Informational Note No. 2: Since there is no consistent relationship between explosionproperties and ignition temperature, the two are independent requirements.

Informational Note No. 3: Low ambient conditions require special consideration. Explosionproof or dust-ignition proof equipment may not be suitable for use at temperatures lower than -25°C (-13°F) unless they are identified for low-temperature service. However, at low ambienttemperatures, flammable concentrations of vapors may not exist in a location classified as ClassI, Division 1 at normal ambient temperature.

(A) Suitability. Suitability of identified equipment shall be determined by one of the following:

(1) Equipment listing or labeling

(2) Evidence of equipment evaluation from a qualified testing laboratory or inspectionagency concerned with product evaluation

(3) Evidence acceptable to the authority having jurisdiction Such as a manufacturer's self-evaluation or an owner's engineering judgment

Informational Note: Additional documentation for equipment may include Certificatesdemonstrating Compliance with applicable equipment standards, indicating special conditions ofuse, and other pertinent information. Guidelines for certificates may be found in ANSI/UI.

(B) Approval for Class and Properties.

(1) Equipment shall be identified not only for the class of location but also for the explosive,combustible, or ignitible properties of the specific gas, vapor, dust, or fibers/flyings that will bepresent. In addition, Class I equipment shall not have any exposed surface that operates at atemperature in excess of the autoignition temperature of the specific gas or vapor. Class IIequipment shall not have an external temperature higher than that specified in 500.8 (D)(2).Class III equipment shall not exceed the maximum surface temperatures specified in 503.5.


Standards



500.8 Equipment – cont.

Informational Note: Luminaires and other heat-producing apparatus, switches, circuit breakers,and plugs and receptacles are potential sources of ignition and are investigated for suitability inclassified locations. Such types of equipment, as well as cable terminations for entry intoexplosion proof enclosures, are available as listed for Class I, Division 2 locations. Fixed wiring,however, may utilize wiring methods that are not evaluated with respect to classified locations.Wiring products such as cable, raceways, boxes, and fittings, therefore, are not marked as beingSuitable for Class I, Division 2 locations. Also see 500.8 (C)(6)(a).

(2) Equipment that has been identified for a Division 1 location shall be permitted in a Division 2location of the same class, group, and temperature class and shall comply with (a) or (b) asapplicable.

(a) Intrinsically safe apparatus having a control drawing requiring the installation ofassociated apparatus for a Division l installation shall be permitted to be installed in a Division 2location if the same associated apparatus is used for the Division 2 installation.

(b) Equipment that is required to be explosion proof shall incorporate seals in accordancewith 501.15(A) or (D) when the wiring methods of 501.10(B) are employed.

(3) Where specifically permitted in Articles 501 through 503, general-purpose equipment orequipment in general-purpose enclosures shall be permitted to be installed in Division 2locations if the equipment does not constitute a source of ignition under normal operatingconditions.

(4) Equipment that depends on a single Compression seal, diaphragm, or tube to preventflammable Or Combustible fluids from entering the equipment shall be identified for a Class I,Division 2 location even if installed in an unclassified location. Equipment installed in a Class I,Division 1 location shall be identified for the Class I, Division 1 location.

Informational Note: Equipment used for flow measurement is an example of equipment havinga single Compression seal, diaphragm, or tube.

(5) Unless otherwise specified, normal operating conditions for motors shall be assumed to berated full-load steady conditions.


Standards




(6) Where flammable gases, flammable liquid-produced vapors, combustible liquid-producedvapors, or combustible dusts are or may be present at the same time, the simultaneous presenceof both shall be considered when determining the safe operating temperature of the electricalequipment.

Informational Note: The characteristics of various atmospheric mixtures of gases, vapors, anddusts depend on the specific material involved.

(C) Marking. Equipment shall be marked to show the environment for which it has beenevaluated. Unless otherwise specified or allowed in (C)(6), the marking shall include theinformation specified in (C)(1) through (C) (5).

(1) Class. The marking shall specify the class(es) for which the equipment is suitable.

(2) Division. The marking shall specify the division if the equipment is suitable for Division 2only. Equipment suitable for Division 1 shall be permitted to omit the division marking.

Informational Note: Equipment not marked to indicate a division, or marked “Division ll” or “Div.l,” is suitable for both Division 1 and 2 locations; see 500.8 (B)(2). Equipment marked "Division 2"or "Div. 2" is suitable for Division 2 locations only.

(3) Material Classification Group. The marking shall specify the applicable materialclassification group(s) or specific gas, vapor, dust, or fiber/flying in accordance with 500.6.

Exception: Fixed luminaires marked for use only in Class I, Division 2 or Class II, Division 2locations shall not be required to indicate the group.

Informational Note: A specific gas, vapor, dust, or fiber/flying is typically identified by thegeneric name, chemical formula, CAS number, or combination thereof.

(4) Equipment Temperature. The marking shall specify the temperature class or operatingtemperature at a 40°C ambient temperature, or at the higher ambient temperature if theequipment is rated and marked for an ambient temperature of greater than 40°C. For equipmentinstalled in a Class II, Division I location, the temperature class or Operating temperature shall bebased on Operation of the equipment when blanketed with the maximum amount of dust thatcan accumulate on the equipment. The temperature class, if provided, shall be indicated usingthe temperature class (T codes) shown in Table 500.8 (C). Equipment for Class I and Class II shallbe marked with the maximum safe operating temperature, as determined by simultaneousexposure to the combinations of Class I and Class II conditions.


Standards




Exception: Equipment of the non-heat-producing type, such as junction boxes, conduit, andfittings, and equipment of the heat-producing type having a maximum temperature not morethan 100°C shall not be required to have a marked operating temperature or temperature class.

Informational Note: More than one marked temperature class Or Operating temperature, forgases and vapors, dusts, and different ambient temperatures, may appear.

(5) Ambient Temperature Range. Electrical equipment designed for use in the ambienttemperature range between - 25°C to +40°C shall require no ambient temperature marking. Forequipment rated for a temperature range other than -25°C

(6) Special Allowances.

(a) General-Purpose Equipment. Fixed general-purpose equipment in Class I locations, otherthan fixed luminaires, that is acceptable for use in Class I, Division 2 locations shall not berequired to be marked with the class, division, group, temperature class, or ambient temperaturerange.

(b) Dust tight Equipment. Fixed dust tight equipment, other than fixed luminaires, that isacceptable for use in Class II, Division 2 and Class III locations shall not be required to be markedwith the class, division, group, temperature class, or ambient temperature range.

(c) Associated Apparatus. Associated intrinsically safe apparatus and associatednonincendive field wiring apparatus that are not protected by an alternative type of protectionshall not be marked with the class, division, group, or temperature class. Associated intrinsicallysafe apparatus and associated nonincendive field wiring apparatus shall be marked with theclass, division, and group of the apparatus to which it is to be connected.

(d) Simple Apparatus. "Simple apparatus" as defined in Article 504, shall not be required tobe marked with class, division, group, temperature class, or ambient temperature range.


Standards




(D) Temperature.

(1) Class I Temperature. The temperature marking specified in 500.8 (C) shall not exceed theauto ignition temperature of the specific gas or vapor to be encountered.

Informational Note: For information regarding auto ignition temperatures of gases and vapors,see NFPA 497-2013, Recommended Practice for the Classification of Flammable Liquids, Gases,or Vapors, and of Hazardous (Classified) Locations for Electrical Installations in Chemical ProcessAreas.

(2) Class II Temperature. The temperature marking specified in 500.8 (C) shall be less than theignition temperature of the specific dust to be encountered. For organic dusts that maydehydrate or carbonize, the temperature marking shall not exceed the lower of either theignition temperature or 165°C (329°F).

The table below (500.8(C)) describes the maximum surface temperature of a motorunder any operating condition, normal or abnormal. The surface temperature must not exceedthe minimum ignition temperature of the substances found in the hazardous location.

Table 500.8(C). Classification of Maximum Surface TemperatureMaximum Temperature Identification

NumberDegrees C Degrees F450 842 T1300 572 T2280 536 T2A260 500 T2B230 446 T2C215 419 T2D200 392 T3180 356 T3A165 329 T3B160 320 T3C135 275 T4120 248 T4A100 212 T585 185 T6


Standards



501.125. Motors and Generators, Class I, Divisions 1 and 2

(A) Class I, Division 1. In Class I, Division 1 locations, motors, generators, and other rotatingelectrical machinery shall be one of the following:

(1) Identified for Class I, Division 1 locations

(2) Of the totally enclosed type supplied with positive pressure ventilation from a source of cleanair with discharge to a safe area, so arranged to prevent energizing of the machine untilventilation has been established and the enclosure has been purged with at least 10 Volumes ofair, and also arranged to automatically de-energize the equipment when the air supply fails

(3) Of the totally enclosed inert gas-filled type supplied with a suitable reliable source of inertgas for pressurizing the enclosure, with devices provided to ensure a positive pressure in theenclosure and arranged to automatically de-energize the equipment when the gas supply fails

(4) For machines that are for use only in industrial establishments with restricted public access,where the conditions of maintenance and supervision ensure that only qualified persons servicethe installation, the machine is permitted to be of a type designed to be submerged in a liquidthat is flammable only when vaporized and mixed with air, or in a gas or vapor at a pressuregreater than atmospheric and that is flammable only when mixed with air; and the machine is soarranged to prevent energizing it until it has been purged with the liquid or gas to exclude air,and also arranged to automatically de-energize the equipment when the supply of liquid or gasor vapor fails or the pressure is reduced to atmospheric

Totally enclosed motors of the types specified in 501.125(A)(2) or (A) (3) shall have noexternal surface with an Operating temperature in degrees Celsius in excess of 80 percent of theauto ignition temperature of the gas or vapor involved. Appropriate devices shall be provided todetect and automatically de-energize the motor or provide an adequate alarm if there is anyincrease in temperature of the motor beyond designed limits. Auxiliary equipment shall be of atype identified for the location in which it is installed.

(B) Class I, Division 2. In Class I, Division 2 locations, motors, generators, and other rotatingelectrical machinery shall comply with (l), (2), or (3). They shall also comply with (4) and (5), ifapplicable.

(1) Be identified for Class I, Division 2 locations, or


Standards



501.125. Motors and Generators, Class I, Divisions 1 and 2 – cont.

(2) Be identified for Class I, Division l locations where sliding contacts, Centrifugal Or Othertypes of Switching mechanism (including motor Overcurrent, Overloading, and Overtemperature devices), or integral resistance devices, either while starting or while running, areemployed, or

(3) Be opera or non-explosion proof enclosed motors, such as squirrel-cage induction motorswithout brushes, Switching mechanisms, or similar arc-producing devices that are not identifiedfor use in a Class I, Division 2 location.

(4) The exposed surface of space heaters used to prevent condensation of moisture duringshutdown periods shall not exceed 80 percent of the auto ignition temperature in degreesCelsius of the gas or vapor involved when operated at rated voltage, and the maximum spaceheater surface temperature based on a 40°C or higher marked ambient shall be permanentlymarked on a visible nameplate mounted on the motor. Otherwise, space heaters shall beidentified for Class I, Division 2 locations.

(5) A sliding contact shaft bonding device used for the purpose of maintaining the rotor atground potential, shall be permitted where the potential discharge energy is determined to benonincendive for the application. The shaft bonding device shall be permitted to be installed onthe inside or the outside of the motor.


Standards



502.125. Motors and Generators, Class II, Divisions 1 and 2

(A) Class II, Division 1. In Class II, Division 1 locations, motors, generators, and other rotatingelectrical machinery shall be in Conformance with either of the following:

(1) Identified for the location

(2) Totally enclosed pipe-ventilated

(B) Class II, Division 2. In Class II, Division 2 locations, motors, generators, and other rotatingelectrical equipment shall be totally enclosed non-ventilated, totally enclosed pipe ventilated,totally enclosed water-air-cooled, totally enclosed fan-cooled, or dust-ignition proof, for whichmaximum full-load external temperature shall be in accordance with 500.8 (D) (2) for normalOperation when operating in free air (not dust blanketed) and shall have no external openings.

Exception: If the authority having jurisdiction believes accumulations of nonconductive,nonabrasive dust will be moderate and if machines can be easily reached for routine cleaningand maintenance, the following shall be permitted to be installed:

(1) Standard open-type machines without sliding contacts, centrifugal or other types ofswitching mechanism (including motor overcurrent, overloading, and over temperaturedevices), or integral resistance devices

(2) Standard open-type machines with such contacts, switching mechanisms, or resistancedevices enclosed within dust tight housings without ventilating or other openings

(3) Self-cleaning textile motors of the squirrel-cage type

(4) Machines with sealed bearings, bearing isolators, and seals


Standards



503.125. Motors and Generators, Class III, Divisions 1 and 2

Class III, Divisions 1 and 2. In Class III, Divisions l and 2 locations, motors, generators, and otherrotating machinery shall be totally enclosed non-ventilated, totally enclosed pipe ventilated, ortotally enclosed fan cooled.

Exception: In locations where, in the judgment of the authority having jurisdiction, onlymoderate accumulations of lint or flyings are likely to Collect on, in, or in the vicinity of arotating electrical machine and where such machine is readily accessible for routine cleaningand maintenance, one of the following shall be permitted:

(1) Self-cleaning textile motors of the squirrel-cage type

(2) Standard open-type machines without sliding contacts, centrifugal or other types ofswitching mechanisms, including motor overload devices

(3) Standard open-type machines having such contacts, switching mechanisms, or resistancedevices enclosed within tight housings without ventilating or other openings


Standards



505.5 Classifications of Locations

Class 1, Zone 1 and 2 locations are those in which flammable gases or vapors are, or maybe, present in the air in quantities sufficient to produce explosive or ignitable mixtures. (2) Class 1, Zone 1. Is a location

(1) In which ignitable concentrations of flammable gases or vapors are likely to existunder normal operating conditions; or

(2) In which ignitable concentrations of flammable gases or vapors may exist frequentlybecause of repair or maintenance operations or because of leakage; or

(3) In which equipment is operated or processes are carried on, of such a nature thatequipment breakdown or faulty operations could result in the release of ignitableconcentrations of flammable gases or vapors and also cause simultaneous failure ofelectrical equipment in a mode to cause the electrical equipment to become a sourceof ignition; or

(4) That is adjacent to a Class I, Zone 0 location from which ignitable concentrations ofvapors could be communicated, unless communication is prevented by adequatepositive pressure ventilations from a source of clean air and effective safeguardsagainst ventilation failure are provided.

Informational Note No. 1: Normal operation is considered the situation when plant equipmentis operating within its design parameters. Minor releases of flammable material may be part ofnormal operations. Minor releases include the releases from mechanical packings on pumps.Failures that involve repair or shutdown (such as the breakdown of pump seals and flangegaskets, and spillage caused by accidents) are not considered normal operation.


Standards



505.5 Classifications of Locations – cont.

(3) Class 1, Zone 2. Is a location(1) In which ignitable concentrations of flammable gases or vapors are not likely to occur

in normal operation and, if they do occur, will exist only for a short period; or(2) In which volatile flammable liquids, flammable gases or flammable vapors are

handled, processed, or used but in which the liquids, gases, or vapors are normallyconfined to closed containers and can only escape as a result of an accidental ruptureor breakdown of container system, or as a result of the abnormal operation of theequipment with which the liquids or gases are handled, processed, or used; or

(3) In which ignitable concentrations of flammable gases or vapors normally areprevented by positive mechanical ventilation but which may become hazardous as aresult of failure or abnormal operation of the ventilation equipment; or

(4) That is adjacent to a Class 1, Zone 1 location, from which ignitable concentrations offlammable gases or vapors could be communicated, unless such communication isprevented by adequate positive pressure ventilation from a source of clean air andeffective safeguards against ventilation failure are provided.

Informational Note: The Zone 2 classification usually includes locations where volatile flammableliquids or flammable gases or vapors are used but which would become hazardous only in caseof an accident or of some unusual operating condition.


Standards



505.8 Protection Techniques

(A) Flameproof “d”. Type of protection where the enclosure will withstand an internal explosionof a flammable mixture that has penetrated into the interior, without suffering damage andwithout causing ignition, through any joints or structural openings in the enclosure of anexternal explosive gas atmosphere Consisting of one or more of the gases or vapors forwhich it is designed. This protection technique shall be permitted for equipment in Class I,Zone 1 or Zone 2 locations for which it is identified.

(B) Pressurization “p”. Type of protection for electrical equipment that uses the technique ofguarding against the ingress of the external atmosphere, which may be explosive, into anenclosure by maintaining a protective gas therein at a pressure above that of the externalatmosphere. This protection technique shall be permitted for equipment in Class I, Zone 1 orZone 2 locations for which it is identified.

(C) Intrinsic Safety “i”. Type of protection where any spark or thermal effect is incapable ofCausing ignition of a mixture of flammable or combustible material in air under prescribedtest Conditions. This protection technique shall be permitted for equipment in Class I, Zone0, Zone 1 or Zone 2 locations for which it is identified.

Informational Note No. 2: Intrinsic safety is designated type of protection “ia" for use inZone 0 locations. Intrinsic safety is designated type of protection "ib" for use in Zone Ilocations.Intrinsic Safety is designated type of protection "ic” for use in Zone 2 locations.

Informational Note No. 3: Intrinsically safe associated apparatus, designated by ia), ib), oric), is connected to intrinsically safe apparatus (“ia,” “ib,” or "ic,” respectively) but is locatedoutside the hazardous (classified) location unless also protected by another type ofprotection (such as flameproof).

(D) Type of Protection “n”. Type of protection where electrical equipment, in normal operation,is not capable of igniting a surrounding explosive gas atmosphere and a fault capable ofcausing ignition is not likely to occur. This protection technique shall be permitted forequipment in Class I, Zone 2 locations for which it is identified. Type of protection “n” isfurther divided into nA, nC, and nR.

(E) Oil Immersion “o”. Type of protection where electrical equipment is immersed in aprotective liquid in such a way that an explosive atmosphere that may be above the liquid oroutside the enclosure cannot be ignited. This protection technique shall be permitted forequipment in Class I, Zone 1 or Zone 2 locations for which it is identified.


Standards



505.8 Protection Techniques – cont.

(F) Increased Safety “e”. Type of protection applied to electrical equipment that does notproduce arcs or sparks in normal service and under specified abnormal conditions, in whichadditional measures are applied so as to give increased security against the possibility ofexcessive temperatures and of the occurrence of arcs and sparks. This protection techniqueshall be permitted for equipment in Class I, Zone 1 or Zone 2 locations for which it isidentified.

(G) Encapsulation “m”. Type of protection where electrical parts that could ignite an explosiveatmosphere by either sparking or heating are enclosed in a compound in such a way that thisexplosive atmosphere cannot be ignited. This protection technique shall be permitted forequipment in Class I, Zone 0, Zone 1 or Zone 2 locations for which it is identified.

Informational Note No. 2: Encapsulation is designated type of protection "ma" for use inZone 0 locations. Encapsulation is designated type of protection "m" or "mb” for use in Zone1 locations. Encapsulation is designated type of protection "mc" for use in Zone 2 locations.

(H) Powder Filling “q”. Type of protection where electrical parts capable of igniting an explosiveatmosphere are fixed in position and completely surrounded by filling material (glass orquartz powder) to prevent the ignition of an external explosive atmosphere. This protectiontechnique shall be permitted for equipment in Class I, Zone 1 or Zone 2 locations for which itis identified.


Standards



Table 5.4. Siemens offerings for applications in the areas as defined by the NEC.Class ofLocation

Motor to be Supplied Comments

Class IDivision I

1. Approved motor(CSA Listed and labeled)

Specific Class and group approval required.

2. Totally-enclosed pipe-ventilated (purged andpressurized enclosures NFPA496)

Possible in some ratings, but no standard line exists. Inlet andexhaust from clean area and other special requirements. Eachapplication must receive individual study. Consult factory.

3. Totally-enclosed inert-gasfilled

No standard line available

Class IDivision 2


Need not have label

2. Totally-enclosed pipe-ventilated

Possible in some ratings, but no standard line exists. Inlet andexhaust from clean area and other special requirements. Eachapplication must receive individual study. Consult factory.

3. TEFCSurface temp. must not exceed 80% of the ignition temperatureof gas or vapor

4. Open

The NEC permits the use of open motor in these locations.Surface temp. Must not exceed 80% of the ignition temp of gas orvapor involved. With no specific data available, Siemens willsupply open motors with motor and heater surface temp of 200C.Lower temps can be provided when specifically requested.

Class IIDivision 1


Specific class and group approval required. Group E, F, and Gavailable in many ratings.

2. Totally-enclosed pipe-ventilated

Totally enclosed pipe-ventilated motors are permitted by NEC, butno standard line exists. Consult factory.

Class IIDivision 2


This is what we recommend for all Class II., Division 2 areas andthe only type we will furnish for Group F options.

2. Totally-enclosed Pipe-Ventilated

Possible in some ratings, but no standard line exists. Eachapplication must receive individual study.

3. Open / TEFC

The NEC permits the use of open or TEFC motors if they areacceptable to the authority having jurisdiction at the end uselocation. Siemens will not knowingly supply open motors forthese applications. Siemens cannot claim that the TEFC motor issuitable for use in these locations. The customer must accepttotal responsibility when obtaining such approval.

Class IIIDivisions1 & 2

1. TEFC

2. TENV and Totally EnclosedPipe-Ventilated

Permitted by the NEC but no standard line available.

Notes:1. National Electrical Code, NFPA No. 70. The publication provides greater detail on classifications than is summarizedin this article. The 2017 edition was used in the preparation of this section.2. All motors for Class I and II, Division 1 hazardous locations shall be equipped with thermostats.


Standards


Canadian Standards Association (CSA)

Most motors sold and all used in Canada require CSA certification. This involvessubmitting details for CSA review and the testing of motors. Below is a tabulation of motorswhich are presently certified to CSA Standards. Please check the CSA website for the most recentinformation, as the following information gets updated frequently.

CSA Certification File No. LR 15721

Horizontal Motors for Ordinary LocationsHorizontal, three phase, squirrel cage induction motors and/or generators, Class F

insulation, 50 or 60 hertz. Table 5.5. Maximum Available Ratings - Horizontal Motors

Type Max HP Max kW Max V Enclosure FrameCG 800 597 6900 ODP,WPI 507, 509, 5011CG 1250 932 6900 ODP,WPI 508, 5010CG 9000 6711 13800 ODP,WPI 8010, 8012CG 2000/1000 1492/746 6900/600 ODP,WPI 588, 5810CG 2500/1000 1865/746 6900/600 ODP,WPI 5812CG 5000/1250 3730/935 6900/600 ODP,WPI 6811, 6813

CGII 800 597 6900 WPII 507, 509, 5011CGII 1250 932 6900 WPII 508, 5010CGII 9000 6711 13800 WPII 8010, 8012CGII 2000/1000 1492/746 6900/600 WPII 588, 5810CGII 2500/1000 1865/746 6900/600 WPII 5812CGII 5000/1250 3730/935 6900/600 WPII 6811, 6813CGII 8300 13200 13800 WPII SH710CGG 800 597 6900 TEWAC 507, 509, 5011CGG 1250 932 6900 TEWAC 508, 5010CGG 9000 6711 13800 TEWAC 8010, 8012CGG 2000/1000 1492/746 6900/600 TEWAC 588, 5810CGG 2500/1000 1865/746 6900/600 TEWAC 5812CGG 5000/1250 3730/935 6900/600 TEWAC 6811, 6813CGG 6500 13200 13800 TEWAC SH710CGP 1250 932 6900 PV 508, 5010CGP 5000/1250 3730/935 6900/600 PV 6811, 6813CGZ 500 373 6900 TEFC 507, 509, 5011CGZ 900 672 6900 TEFC 588, 5810CGZ 1500 1119 7200 TEFC 708CGZ 2000 1492 7200 TEFC 788CGZ 2500 1865 7200 TEFC 880CAZ 7000 5220 13800 TEAAC 8010, 8012CAZ 4000/1250 2983/935 6900/600 TEAAC 6811, 6813CAZ 11500 8576 6600 TEAAC SH710


Standards



Vertical Motors for Ordinary LocationsVertical, three phase, squirrel cage induction motors and/or generators, Class F insulation, 50 or60 hertz.Ma

Table 5.5-cont. Maximum Available Ratings - Horizontal MotorsType Max HP Max kW Max V Enclosure Frame

CGV, CGHS 2000 1492 6900 ODP, WPI507, 509, 588,

5810CGV, CGHS 6000 4500 6900 ODP, WPI 680, 800, 1120

CGIIV, CGIIHS 2000 1492 6900 WPII507, 509, 588,

5810

CGZV, CGZHS 2000 1492 6900 TEFC507, 509, 588,

5810CAZV, CAZBV 4500 3300 6900 TEAAC 680, 800, 1120

Notes:1. The motor type designation may also have the following suffixes: E – High efficiency; F –

Flanged housing; H – High starting torque, high slip; T – High starting torque, low slip.2. The frame size number may also have the suffixes: B, BB, D, P, S, Y, YZ or Z indicating flange

mounting, short shaft, special mounting, etc.3. The tables list maximum values. It is not possible to obtain the maximum output at all

voltages and at all speeds. Refer to the frame assignment charts presented elsewhere in thismanual. Consult the factory for specific information.

AccessoriesAuxiliary devices such as current transformers, surge arrestors, surge capacitors, space

heaters, etc. are available on CSA certified motors. Consult the factory if specific brands or typesof such instruments are required.

Special MarkingsThe CSA symbol will appear on the nameplate of all CSA certified motors when shipped

to Canada. The CSA marking is optional when the certified motors are shipped within the UnitedStates. The month and year of manufacture will also appear. Any required warning labels willalso be affixed to the motor.

Hazardous Location MotorsMotors are also available for application in areas of various Classes, Groups, and

Divisions. Consult the factory for availability of specific units.


Standards



TestingCSA C390 meets NVLAP testing for Canada for voltages up to 600V and power ratings up

to 500HP.

This standard covers instructions for the conducting and reporting the more generally applicableand acceptable tests to determine the performance characteristics of poly-phase inductionmotors and generators.


Testing


Table of ContentsNorwood Testing Facility ................................................................................................................... 2 Testing Capabilities ............................................................................................................................ 2 Routine Test....................................................................................................................................... 3 Complete Test, Method F1 ................................................................................................................. 4 Complete Test, Method E1 ................................................................................................................. 5 Complete Test, Method B ................................................................................................................... 6 API Standard 541 Routine Test ........................................................................................................... 7 API Standard 541 Complete Test, Method F1 ..................................................................................... 8 API Standard 541 Complete Test, Method E1 ..................................................................................... 9

API Standard 541 Complete Test, Method B..................................................................................... 10 API Standard 547 Routine Test ......................................................................................................... 11


Testing


Norwood Testing Facility

Testing Capabilities - Recentinvestments of over $5 million!

· Shaft load heat run & IEEE 112method E1 efficiency at 60 Hz formotors ranging from 460-13,800volts has capabilities on 2 pole upto 10,000HP, 4 pole up to 20,000HP & 6 pole up to 13,300HP.*After update is completed inMarch 2018, we will be able to test at any frequency up to shaft speeds of 3600 RPM.Consult factory for deviations. (not applicable for vertical motors)

· Motors above 8,000 volts are tested in Delta at equivalent flux density· Extrapolated shaft load heat run (superposition) per IEC 60034-29 & IEEE 112 method E1

efficiency through 18,500 HP for 60 Hz. 2, 4, & 6 pole, 4,000-13,800 volt motors.Consult factory for deviations. (not applicable for vertical motors)

· Shaft load heat run & IEEE 112 method E1 efficiency at 50 Hz for motors ranging from2,000-11,000 volts has capabilities on 2 pole up to 10,000HP, 4 pole up to 16,600HP & 6pole up to 11,000HP. Consult factory for deviations. 50 Hz. heat run tests will beperformed at equivalent flux density at 60 Hz., unless specified otherwise by customer.(not applicable for vertical motors)

· Efficiency only (without temperature test) IEEE 112 method E1 efficiency thru 10,000 HPfor 60 Hz. 2,300 – 13,800 volt motors. Consult factory for deviations. (not applicable forvertical motors)

· Dual frequency heat run & IEEE 112 method F1 efficiency through 3,000 HP for 60 Hz.2,300 – 8,000 volt motors. Consult factory for deviations. (applicable for verticalmotors)

· Efficiency only (without temperature test) IEEE 112 method F1 efficiency thru 5,000 HPfor 60 & 50 Hz. 2,300 – 13,800 volt motors. Consult factory for deviations. (applicablefor vertical motors)

· Complete test, Method B at 60Hz, ranging from 460—13,800 volts has capabilities on 2pole up to 10,000HP, 4 pole up to 8,000HP & 6 pole up to 5,500HP. Consult factory fordeviations. (not applicable for vertical motors)

· Can also determine losses and efficiency per IEC 60034-2· System testing through 10,000 HP. Consult factory. (i.e. drive/motor)· 230-13,800 volts, 3 phase sinusoidal power supply for 50 and 60 Hz. Consult factory for

other frequencies.· Over-speed capability through 18,500 HP· AC and DC High-Potential through 60,000 volts· Data acquisition equipment – Calibrated annually per NIST standards


Testing



Routine Test

Calculations and data forms used to determine results of testing from raw data are per IEEE 112 and are retained, not reported.Certified Final Test Report forms submitted to the customer are per IEEE 112, Annex B.

Description Report

Idle run – Measure & record current, volts, power, speed DR/R AC High potential test @ 2X rated volts + 1000 volts DR/R Insulation resistance DR/R Stator winding resistance DR/R Vibration - horizontal, vertical, axial DR/N Bearing insulation DR/N Air gap measurement DR/N [If space heaters ordered] Space heater resistance DR/N [If stator and/or bearing RTD’s ordered] Stator and bearing RTD resistance DR/N [If stator RTD’s ordered] RTD high potential test DR/N [If thermostats ordered ] Thermostat high potential test DR/N [If sleeve bearings] Magnetic center DR/N [If sleeve bearings] Bearing cavity pressure check DR/N [If aluminum rotor] Rotor test DR/N [If B-N probes ordered] Slow roll DR/NLEGENDS:

DR/R = Documentation Retained / Reported DR/N = Documentation Retained / Not reported


Testing



Complete Test, Method F1

Calculations and data forms used to determine results of testing from raw data are per IEEE 112 and are retained, not reported.Certified Final Test Report forms submitted to the customer are per IEEE 112, Annex C.

Description Report Idle run – Measure & record current, volts, power, speed DR/R AC High potential test @ 2X rated volts + 1000 volts DR/R Insulation resistance DR/R Stator winding resistance DR/R Vibration - horizontal, vertical, axial DR/R Bearing insulation DR/N Air gap measurement DR/N [If space heaters ordered] Space heater resistance DR/N [If stator and/or bearing RTD’s ordered] Stator and bearing RTD resistance DR/N [If stator RTD’s ordered] RTD high potential test DR/N [If thermostats ordered] Thermostat high potential test DR/N [If sleeve bearings] Magnetic center DR/N [If sleeve bearings] Bearing cavity pressure check DR/N [If aluminum rotor] Rotor test DR/N [If B-N probes ordered] Slow roll DR/N

Complete Test Report Determine efficiency @ 100, 75 & 50% – Equivalent circuit method (F1) DR/R Determine power factor @ 100, 75 & 50% DR/R Determine locked rotor torque and current DR/R Temperature (heat) run – dual frequency DR/R Measure & record winding temperature rise DR/R Measure & record bearing temperature rise DR/RLEGENDS:



Testing



Complete Test, Method E1


Description Report Idle run – Measure & record current, volts, power, speed DR/R AC High potential test @ 2X rated volts + 1000 volts DR/R Insulation resistance DR/R Stator winding resistance DR/R Vibration - horizontal, vertical, axial DR/R Bearing insulation DR/N Air gap measurement DR/N [If space heaters ordered] Space heater resistance DR/N [If stator and/or bearing RTD’s ordered] Stator and bearing RTD resistance DR/N [If stator RTD’s ordered] RTD high potential test DR/N [If thermostats ordered] Thermostat high potential test DR/N [If sleeve bearings] Magnetic center DR/N [If sleeve bearings] Bearing cavity pressure check DR/N [If aluminum rotor] Rotor test DR/N [If B-N probes ordered] Slow roll DR/N

Complete Test Report Determine efficiency @ 100, 75 & 50% – Segregated loss method (E1) DR/R Determine power factor @ 100, 75 & 50% DR/R Determine locked rotor torque and current DR/R Temperature (heat) run – direct load DR/R Measure & record winding temperature rise DR/R Measure & record bearing temperature rise DR/RLEGENDS:



Testing



Complete Test, Method B


Description Report Idle run – Measure & record current, volts, power, speed DR/R AC High potential test @ 2X rated volts + 1000 volts DR/R Insulation resistance DR/R Stator winding resistance DR/R Vibration DR/R Bearing insulation DR/N Air gap measurement DR/N [If space heaters ordered] Space heater resistance DR/N [If stator and/or bearing RTD’s ordered] Stator and bearing RTD resistance DR/N [If stator RTD’s ordered] RTD high potential test DR/N [If thermostats ordered] Thermostat high potential test DR/N [If sleeve bearings] Magnetic center DR/N [If sleeve bearings] Bearing cavity pressure check DR/N [If aluminum rotor] Rotor test DR/N [If B-N probes ordered] Slow roll DR/N

Complete Test Report Determine efficiency @ 100, 75 & 50% – Input-Output with Loss Segregation method (B) DR/R Determine power factor @ 100, 75 & 50% DR/R Determine locked rotor torque and current DR/R Temperature (heat) run – direct load DR/R Measure & record winding temperature rise DR/R Measure & record bearing temperature rise DR/RLEGENDS:



Testing



API Standard 541 Routine Test


Description Report

Idle run – Measure & record current, volts, power, speed DR/R Determine locked rotor current DR/N AC High potential test @ 2X rated volts + 1000 volts DR/R Insulation resistance and Polarization Index test DR/R Stator winding resistance DR/R Vibration - horizontal, vertical, axial DR/R Bearing insulation DR/N Measure & record bearing temperature rise DR/R Bearing inspection DR/R Air gap measurement DR/NShaft voltage DR/N [If space heaters ordered] Space heater resistance DR/N [If stator and/or bearing RTD’s ordered] Stator and bearing RTD resistance DR/N [If stator RTD’s ordered] RTD high potential test DR/N [If thermostats ordered] Thermostat high potential test DR/N [If sleeve bearings] Magnetic center DR/N [If sleeve bearings] Bearing cavity pressure check DR/N Soft foot check DR/N [If aluminum rotor] Rotor test DR/N [If B-N probes ordered] Slow roll DR/NLEGENDS:



Testing



API Standard 541 Complete Test, Method F1


Description Report Idle run – Measure & record current, volts, power, speed DR/R Determine locked rotor current DR/N AC High potential test @ 2X rated volts + 1000 volts DR/R Insulation resistance and Polarization Index test DR/R Stator winding resistance DR/R Vibration - horizontal, vertical, axial DR/R Bearing insulation DR/N Measure & record bearing temperature rise (1) DR/R Bearing inspection DR/R Air gap measurement DR/NShaft voltage DR/N [If space heaters ordered] Space heater resistance DR/N [If stator and/or bearing RTD’s ordered] Stator and bearing RTD resistance DR/N [If stator RTD’s ordered] RTD high potential test DR/N [If thermostats ordered] Thermostat high potential test DR/N [If sleeve bearings] Magnetic center DR/N [If sleeve bearings] Bearing cavity pressure check DR/N Soft foot check DR/N [If aluminum rotor] Rotor test DR/N [If B-N probes ordered] Slow roll DR/N

API Std 541, 3rd Complete Test Report Determine efficiency @ 100, 75 & 50% – Equivalent circuit method (F1) DR/R Determine power factor @ 100, 75 & 50% DR/RDetermine locked rotor power factor DR/NDetermine full load current and slip DR/R Determine locked rotor torque and breakdown torque DR/R Temperature (heat) run – dual frequency (Minimum 4-hours) DR/R Measure & record winding temperature rise DR/R Speed-torque curve DR/N Noise Test DR/RLEGENDS:

DR/R = Documentation Retained / Reported DR/N = Documentation Retained / Not reportedNOTES:

(1) When a complete test is purchased Siemens will perform a 4 hour heat run per 4.3.5.1.1e. Bearing temperature rise and vibration data will be taken duringthe 4 hour heat run. A separate no load heat run per 4.3.2i will not be performed.


Testing



API Standard 541 Complete Test, Method E1


Description Report Idle run – Measure & record current, volts, power, speed DR/R Determine locked rotor current DR/N AC high potential test @ 2X rated volts + 1000 volts DR/R Insulation resistance and Polarization Index test DR/R Stator winding resistance DR/R Vibration - horizontal, vertical, axial (2) DR/R Bearing insulation DR/N Measure & record bearing temperature rise (1) DR/R Bearing inspection DR/R Air gap measurement DR/N Shaft voltage DR/N [If space heaters ordered] Space heater resistance DR/N [If stator and/or bearing RTD’s ordered ] Stator and bearing RTD resistance DR/N [If stator RTD’s ordered] RTD high potential test DR/N [If thermostats ordered] Thermostat high potential test DR/N [If sleeve bearings] Magnetic center DR/N [If sleeve bearings] Bearing cavity pressure check DR/N Soft foot check DR/N [If aluminum rotor] Rotor test DR/N [If B-N probes ordered] Slow roll DR/N

API Std 541, 3rd Complete Test Report Determine efficiency @ 100, 75 & 50% – Segregated loss method (E1) DR/R Determine power factor @ 100, 75 & 50% DR/R Determine locked rotor power factor DR/NDetermine full load current and slip DR/R Determine locked rotor torque and breakdown torque DR/R Temperature (heat) run – direct load (Minimum 4-hours) DR/R Measure & record winding temperature rise DR/R Speed-torque curve DR/N Noise Test DR/RLEGENDS:

DR/R = Documentation Retained / Reported DR/N = Documentation Retained / Not reportedNOTES:

(1) When a complete test is purchased Siemens will perform a 4-hour heat run per 4.3.5.1.1e. Bearing temperature rise and vibration data will be taken duringthe 4-hour heat run. A separate no load heat run per 4.3.2i will not be performed.

(2) Acceptance criteria based on uncoupled readings


Testing



API Standard 541 Complete Test, Method B


Description Report Idle run – Measure & record current, volts, power, speed DR/R Determine locked rotor current DR/N AC high potential test @ 2X rated volts + 1000 volts DR/R Insulation resistance and Polarization Index test DR/R Stator winding resistance DR/R Vibration - horizontal, vertical, axial (2) DR/R Bearing insulation DR/N Measure & record bearing temperature rise (1) DR/R Bearing inspection DR/R Air gap measurement DR/N Shaft voltage DR/N [If space heaters ordered] Space heater resistance DR/N [If stator and/or bearing RTD’s ordered ] Stator and bearing RTD resistance DR/N [If stator RTD’s ordered] RTD high potential test DR/N [If thermostats ordered] Thermostat high potential test DR/N [If sleeve bearings] Magnetic center DR/N [If sleeve bearings] Bearing cavity pressure check DR/N Soft foot check DR/N [If aluminum rotor] Rotor test DR/N [If B-N probes ordered] Slow roll DR/N

API Std 541, 3rd Complete Test Report Determine efficiency @ 100, 75 & 50% – Input-Output with Loss Segregation method (B) DR/R Determine power factor @ 100, 75 & 50% DR/R Determine locked rotor power factor DR/NDetermine full load current and slip DR/R Determine locked rotor torque and breakdown torque DR/R Temperature (heat) run – direct load (Minimum 4-hours) DR/R Measure & record winding temperature rise DR/R Speed-torque curve DR/N Noise Test DR/RLEGENDS:


NOTES:

(1) When a complete test is purchased Siemens will perform a 4-hour heat run per 4.3.5.1.1e. Bearing temperature rise and vibration data will be taken duringthe 4-hour heat run. A separate no load heat run per 4.3.2i will not be performed.

(2) Acceptance criteria based on uncoupled readings


Testing



API Standard 547 Routine Test


Description Report Idle run – Measure & record current, volts, power, speed DR/R Determine locked rotor current DR/N AC High potential test @ 2X rated volts + 1000 volts DR/R Insulation resistance and Polarization Index test DR/R Stator winding resistance DR/R Vibration - horizontal, vertical, axial DR/R Bearing insulation DR/N Measure & record bearing temperature rise DR/R Air gap measurement DR/NShaft voltage DR/N [If space heaters ordered] Space heater resistance DR/N [If stator and/or bearing RTD’s ordered] Stator and bearing RTD resistance DR/N [If stator RTD’s ordered] RTD high potential test DR/N [If thermostats ordered] Thermostat high potential test DR/N [If sleeve bearings] Magnetic center DR/N [If sleeve bearings] Bearing cavity pressure check DR/N Soft foot check DR/N [If aluminum rotor] Rotor test DR/N [If B-N probes ordered] Slow roll DR/NLEGENDS:



Special Applications and Formulae


Table of ContentsPower Factor Correction .................................................................................................................... 2Starting Methods ............................................................................................................................... 6 Methods of Starting Three Phase A.C. Induction Motors ..................................................................... 6 Full Voltage Start ............................................................................................................................... 7 Reduced Voltage Start ........................................................................................................................ 8 Autotransformer Type Starting Operation ....................................................................................... 8 Primary Resistor or Reactor Starting Operation .............................................................................. 10 Solid State Starters ........................................................................................................................ 11 Ajustable Frequency Drives ......................................................................................................... 11 Increment Starting ........................................................................................................................... 12 Part-Winding Start – ½ Winding Method ........................................................................................ 12 Wye-Delta Starting ........................................................................................................................ 13 Typical Speed vs. Current Curve- Squirrel Cage Induction Motor .................................................... 19 Typical Speed vs Torque Curves- Low Terminal Voltage Squirrel Cage Induction Motors ................ 20 Motor Starters and Schematic Diagrams .......................................................................................... 21Duty Cycles and Inertia .................................................................................................................... 22 Horsepower Variations ..................................................................................................................... 22 Accelerating Time ............................................................................................................................ 23 Moment of Inertia (WK2) .................................................................................................................. 23 Calculation of Inertia of Shafts ......................................................................................................... 24 WK2 of Steel Shafting and Disc ......................................................................................................... 25 High WK2 Acceleration ..................................................................................................................... 26 Information Required for Proper Selection ....................................................................................... 27Special Applications......................................................................................................................... 28 Accelerating Rotary Compressors and Vacuum Pumps ..................................................................... 28 Motors for Cutting Water Pumps for Decokers .................................................................................. 29Formulas and General Data ............................................................................................................. 30 Determination of HP Requirements .................................................................................................. 30Adjustable Frequency Drive ............................................................................................................ 33 Types of Loading: Variable/Constant Torque and Constant Horsepower ........................................... 34 Operating Range .............................................................................................................................. 35 Torque Requirement ........................................................................................................................ 37 Insulation System ............................................................................................................................ 40 Cable Length ................................................................................................................................... 42 Insulated Bearings ........................................................................................................................... 42 Siemens Norwood IGBT Policy Statement ......................................................................................... 43 Marketing Quotation Guidelines ...................................................................................................... 44 Drive By-Pass Capability ................................................................................................................... 46 Noise ............................................................................................................................................... 46




Power Factor Correction

Terms:Apparent Power: The total kilovolt-amperes (KVA) a motor is demanding from the power supply.Actual Power: The real power being used by a motor to drive the connected load (Expressed as

watts or kilowatts (KW)).Reactive power: The reactive component drawn by the motor due to the magnetic fields and

leakage reactance. Expressed as kilovolt-amperes reactive (KVAR).

Power factor is the ratio of the actual power to the apparent power. It is generallyexpressed in percentage. When apparent power (KVA) exceeds the actual power (KW) acomponent known as reactive power (KVAR) is present. The apparent power consists of twoparts: actual power which results in useful work, and reactive power which merely bouncesenergy back and forth. Both generate heat in the wires or conductors. The reactive power isalways present in inductive load devices and is actually part of the total current indicated byammeter reading. However, it does not register on a kilowatt hour meter.

The inductive reactance of the A.C. induction motor causes the motor current to lagbehind the motor voltage, and thereby causes the power factor to drop below unity. This can beoffset by the addition of capacitors preferably connected in such a manner that they areautomatically removed from the system as the power source is removed from the motor (SeeFigures 7.1 and 7.2).

Figure 7.1. Capacitor Options Figure 7.2. Apparent vs. Reactive Power

The capacitors can be connected in one of two ways:A) Capacitor Option 1 should be considered for multi-speed motors, motors connected tohigh inertia loads, or motors that are repeatedly started, multi-jogged, or plugging duty(plug reversed).B) Capacitor Option 2 could be considered if none of the applications mentioned aboveapply.

NOTE: THE OPEN CIRCUIT TIME CONSTANT OF THE MOTOR WILL INCREASECONSIDERABLY DUE TO CAPACITOR ADDITION





The capacitor causes the current to lead the voltage, which tends to offset the laggingcurrent caused by the motor reactance, thereby improving the system power factor. Thecapacitive current in the capacitors opposes the inductive current in the induction motor.

Low power factor increases the power company’s cost of supplying actual power becausemore current must be transmitted than is actually used to perform useful work. The additionaltransmitted current increases the cost incurred by the power company and is directly billed tothe consumer by means of power factor clauses in the rate schedules. Low power factor reducesthe load handling capability of the industrial plants electrical system as well as the load handlingcapabilities of the power company’s generators, transmissions lines, and transformers.

Over correction of power factor by the addition of excessive capacitance is dangerous tothe motor and driven equipment; therefore, it is undesirable. Over correction of power factor bythe addition of excessive capacitance must be avoided because:

1. Over correction of power factor may cause damage to the A.C. induction motoras well as the driven equipment. The power factor correction capacitors areelectrical energy storage devices. When the motor is de-energized, thecapacitor, which remains connected in parallel to the motor, can maintain themotor voltage. If the motor is re-energized after a short time, the motorvoltage and the line voltage may be additive, and dangerously high currentsand torques may result. This condition, if present for only a short time, canresult in dangerously high transient currents and torques which can causephysical damage to the motor’s power transmission devices and the drivenload. The important consideration is time. The motor voltage will normallydecay in five seconds or less; therefore, the motor should not be re-energizedbefore five seconds have elapsed.

2. Regenerative effect on A.C. induction motors. The motor power factor shouldnot be corrected on A.C. induction motors connected to loads capable ofcausing the motor to rotate at speeds above synchronous motor speed whenthe motor is de-energized. The addition of power factor correction capacitors,to motors connected to overhauling loads must be done with extreme care.Although the motor and its connected capacitors are de-energized, continuedrotation of the rotor, combined with the stored energy in the capacitor, causesthe motor to act as an alternator (A.C. generator). The voltage generated in theA.C. motor





severely strains the capacitors and may be sufficient to cause destruction of thecapacitors. When power factor correction is required on A.C. motors connectedto overhauling loads, contact the factory for technical assistance.

3. Excessive capacitance applied to an A.C. induction motor will correct the powerfactor of other inductive loads connected to the same power supply source.Since the same power supply system is used to supply power to many inductiveloads, over correction at one load point will correct the power factor at anotherload point. The user that over corrects the power factor of this inductive loaddoes not receive additional financial benefits from the power company. Byallowing the company to supply power having a leading current (current leadsthe voltage) to other customers on the same supply system, the company issaving money.

For these reasons, the power factor of an A.C. induction motor should not be correctedabove 95%. The amount of capacitance, expressed as KVAR, required for power factor correctioncan be determined by use of the formula below. This value will probably fall between standardsizes available from manufacturers. The next lower standard size is usually selected.

The added KVAR should never exceed the no-load magnetizing KVAR of the motor. If theselected correcting value of KVAR exceeds the no load magnetizing KVAR, it must be reduced toavoid over-excitation of the motor. The magnetizing KVAR can be calculated using the followingformula:

= × 3 × −

1000





Table 7.1. Uncorrected motor power factor and constant%PF Ky %PF Ky

60.0 1.333 77.0 0.82960.5 1.316 77.5 0.81561.0 1.299 78.0 0.802

61.5 1.282 78.5 0.78962.0 1.266 79.0 0.77662.5 1.249 79.5 0.76363.0 1.233 80.0 0.75063.5 1.217 80.5 0.73764.0 1.201 81.0 0.72464.5 1.183 81.5 0.71165.0 1.169 82.0 0.69865.5 1.154 82.5 0.68566.0 1.138 83.0 0.67266.5 1.123 83.5 0.65967.0 1.108 84.0 0.64667.5 1.093 84.5 0.63368.0 1.078 85.0 0.62068.5 1.064 85.5 0.60769.0 1.049 86.0 0.59369.5 1.035 86.5 0.58070.0 1.020 87.0 0.56770.5 1.006 87.5 0.55371.0 0.992 88.0 0.54071.5 0.978 88.5 0.52672.0 0.964 89.0 0.51272.5 0.950 89.5 0.49873.0 0.936 90.0 0.48473.5 0.923 90.5 0.47074.0 0.909 91.0 0.45674.5 0.896 91.5 0.44175.0 0.882 92.0 0.42675.5 0.868 92.5 0.41176.0 0.855 93.0 0.395

93.5 0.37994.0 0.36394.5 0.346

95.5 0.842 95.0 ~ 0.329

= .746

∗ ( 1 − 2)

KVAR = Kilovolt amperes reactive required to be added to circuit for Power Factor CorrectionHP = Nameplate motor horsepowerEFF = Motor full load efficiency expressed as a decimal (ex: .95).Ky = the y can either be a 1 or 2 depending on whether it’s your designed power factor or desiredpower factorK1= motor’s designed power factor constantK2= customer’s desired power factor constant




Starting Methods

Methods of Starting Three Phase A.C. Induction Motors

The purpose of all motor starters is to provide a means of connecting the motor to thepower supply thereby accelerating the motor and connected load from standstill to the normaloperating speed.

The following items should be considered when selecting a motor starter for a specificthree phase A.C. induction motor and motor load.

1. The power source (phase, voltage, frequency).2 The starting torque requirements of the load.3. Power source restrictions concerning amperage draw.

Three phase A.C. induction motor starters can be classified into three basic categories.

A. Full Voltage TypeThe full voltage type of across-the-line started simply connects the motor directly to thepower source.

B. Reduced Voltage TypeReduced voltage starters cause a voltage, lower than that of the power source, to beimpressed on the motor terminals in order to reduce motor inrush current and startingtorque. Example:a. Autotransformerb. Series Resistor or Reactorc. Solid State Startersd. Adjustable Frequency Drives

C. Increment TypeIncrement starters use various motor reconnecting techniques to reduce motor inrushcurrent and starting torque. Normal line voltage is maintained at the motor terminals.Example:a. Part Windingb. Wye-Delta




Starting Methods

Full Voltage Start

GeneralAcross-the-line starting is the most basic and widely used method of starting squirrel

cage induction motors and is, therefore, used as a basis for comparing other starting methods.

OperationA pilot device (such as a start push button) closes the line contactor to connect the motor

directly to the line.

Advantages1. The across-the-line starter is the simplest A.C. motor starting device and, therefore, the

least expensive. It provides reliable trouble free operation with low maintenance costs.2. The across-the-line starter allows the A.C. motor to develop its maximum starting torque.

Caution1. The high inrush current (approximately 6.0 to 6.5 times the nameplate full load current)

may be in excess of that allowed by the power company.2. The high motor starting torque may cause excessive shock loading to the driven

equipment.3. The high starting current may cause a temporary reduction in motor terminal voltage.

This voltage drop will reduce the motor starting torque by the square of the voltage ratio.An excessive voltage drop may cause dimming of lights or cause magnetic relays to “tripout”.




Starting Methods

Reduced Voltage Start

1. Autotransformer Type Starting OperationGeneral

The autotransformer starter is classified as a reduced voltage starter. It is a device wherethe applied motor voltage can be reduced below the line voltage. Both motor starting currentand torque will be reduced below those values obtained with across-the-line starting.

Any standard three phase induction motor may be used with an autotransformer starter.The starter portion of the autotransformer start connects the motor leads to the reduced voltageoutput winding of the autotransformer. After a pre-set time delay (normally 10 to 20 seconds)the started connects the motor leads to the full line voltage.

OperationTwo autotransformer starter designs are used, the open-circuit transition and the closed-

circuit (Korndorfer) transition types. Both manual and magnetic open/closed circuit transitionautotransformers are available. During switching from reduced voltage starting to full appliedline voltage operation, the motor is disconnected from voltage supply in the case of the opencircuit transition. For closed circuit operation; however, a voltage is continuously applied to themotor terminals from the moment of reduced voltage starting and during the switching to fullline voltage operation.

Advantages1. Starting torque per starting amp ratio equal to the across-the-line starter.2. The most desirable starting current and starting torque can be selected by means of

reconnecting the motor leads to the 50%, 65%, or 80% output taps of theautotransformer. The characteristics of the motor load and allowable acceleratingtimes establish the best tap connection.

%Tap %LT %LRA50 25 2765 42 4580 64 66

Where:%LT = Starting torque expressed as a percentage of the value encountered during across-the-linestarting.%LRA = Starting current drawn from the power lines expressed as percentage of the valueencountered during across-the-line starting. This value includes the approximate requiredautotransformer magnetization current.




Starting Methods

Reduced Voltage Start – cont.

1. Autotransformer Type Starting Operation – cont.

Note: Both % locked torque and % locked rotor current vary approximately as the square of thevoltage applied to the motor.

3. Limited motor noise and vibration during starting.4. On the closed circuit transition-type starter voltage transients during the transition

period are minimized, which reduces the possibility of unacceptable performance ofother electrical components within the same plant.

Caution1. The autotransformer output tap may need a higher percentage voltage value if the load

torque and/or inertia exceeds the motor’s acceleration, within the required startingperiod.

2. The transfer from reduced voltage to full voltage operation should be delayed until themotor speed is high enough to ensure the current change during switching will notexceed the power company’s requirements.

3. The starter and the motor should be evaluated for applications requiring frequentstarting. For autotransformer starters, NEMA states that four 15 second starting periodsper hour is acceptable. The majority of standard induction motors are capable of four 15second starting periods per hour.

4. On the open-circuit transition type, line voltage transients can result during the transitionperiod due to sudden current changes.




Starting Methods

2. Primary Resistor or Reactor Starting OperationGeneral

Resistor-type starters introduce a resistor bank in series with the motor windings.The initial current surge through the motor is limited by the resistors. Simultaneously, a voltagedrop develops across the resistors, reducing the voltage applied to the motor. At reducedvoltage, the motor torque capability is reduced.

OperationAs the motor begins to accelerate, it produces a counter emf opposing the applied

voltage, and further reduces the initial current surge. As the current surge is reduced, thevoltage drop across the resistor bank diminishes while that of the motor is increased. Thisincreases motor torque while current inrush is diminishing. The net result is a smooth andgradual accelerating cycle without open transients in the motor windings.

An adjustable timing device on the starter is pre-set to initiate a run contactor at theproper time during the accelerating period. This function closes a run contactor, causing shortingacross the resistors. The start contactor then drops open, removing the resistors from the circuit.Reactor-type starters follow the same sequence of starting, with the exception that the reactorsremain shorted after the final stage of acceleration. As implied, the reactors are core wounddevices, having adjustable voltage taps. These devices limit the initial motor current surge by aninherent tendency to oppose a sudden changing condition of current and voltage.

Advantages1. The resistor or reactor controllers are the close transition-type, since the lines to the

motor are not opened during transfer to the run condition.2. Resistors supplied provide 65% voltage, but have taps at 80% to allow for adjustment.

Reactors have 50%, 65%, and 80% taps. All controllers are connected for 65% voltage asstandard.

3. Current drawn from the line upon starting is reduced to approximately the value of thetap used.

4. Starting torque is approximately reduced to the value of the tap squared. For example,with connection to the 65% taps, current inrush will be approximately 65% of full-voltage, locked-rotor current, and starting torque will be about 42% of that developedunder full-voltage starting.

5. Any standard motor may be used. (No special windings or connection are needed.)Caution:

1. The motor will not start if the breakaway torque required of the load exceeds what themotor can develop on the starting connection.

2. Full impact of inrush current and torque are then experienced at transfer from the shortto run connection.




Starting Methods

3. Solid State Starters

Solid state starters provide reduced voltage during starting by controlling the firing angleof Silicon Controlled Rectifiers (SCR’s) during the starting cycle. The firing angle allowsconduction of voltage and current during only a portion of the A-C sine wave.

The most commonly used type of solid state starting is Current Limit Starting. A currentlimit, as a percentage of full load current, is selected at the started controller. Voltage is rampedup until the line current reaches the value selected (typically 175 to 500 percent of full loadcurrent). This current is maintained as the motor accelerates, until the motor has reached aspeed at which its current draw is less than the current limit selected. The torque delivered bythe motor will be approximately:

T = [Current Limit (Percent current at full voltage)]2 x Full voltage motor torque

For example, a motor which delivers 100 percent of full load torque at locked rotor, with650 percent locked rotor amps at full voltage, being started with a solid state started set at 300percent current limit, will deliver (300/650)2 x 100, or 21.3 percent of full load torque at start.

Solid state starters can also be used in conjunction with shaft driven tachometers toprovide controlled acceleration times (up to 30 seconds, maximum). Voltage output is adjustedas required by the starter controller to provide a constant rate of acceleration. It should be notedthat the starter output voltage frequency is not changed from the incoming line frequency. Solidstate starters are usually limited to applications to motors below 1000 horsepower and below575 volts.

a. Adjustable Frequency Drives

Adjustable Frequency Drives (AFD’s) are solid state devices, which control both thevoltage amplitude and frequency seen at the motor’s terminals. When used with motors drivinghigh inertia centrifugal loads, such as fans, AFD’s can be controlled to greatly reduce the powerrequired to start the load and greatly reduce the thermal stresses on the motor duringacceleration.

With normal ATL or autotransformer starting, most of the power drawn by the motor, asit accelerates, is dissipated as heat in the stator or rotor windings. AFDs can be controlled toallow the motor and load to reach near synchronous speed of a reduced frequency terminalvoltage. The power drawn by the motor will be slightly greater than the brake horsepowerrequired by the load at the speed at which the motor and load are rotating. Losses in the motorand motor windings will be minimal in comparison to their losses occurring in an ATL start at thesame speed. Drive output voltage and frequency are gradually ramped up until the motorreaches its final desired speed. AFD application often allows a smaller frame motor to be usedthan would otherwise be required to start inertia loads.




Starting Methods

Increment Starting

1. Part Winding Start - 1/2 Winding Method

GeneralPart winding starting, 1/2 winding type, is the most commonly used method of

increment starting of A.C. induction motors. The 1/2 winding method of part winding starting isused to reduce the initial value of motor starting current and/or to reduce the value of motorstarting torque. The ½ winding method of part winding starting requires the use of a specificmotor starter with an A.C. induction motor having two parallel stator windings suitablyconnected internally for part winding starting.

The starter must be capable of energizing, with full line voltage, 1/2 of the motorwinding. After a slight time delay (not to exceed three seconds), the starter will energize thecomplete winding.

OperationA pilot device (push button) closes contactor 1, connects 1/2 of the motor winding across

the line, and energizes a timer. After a predetermined time interval, the timer closes contactor 2,connecting the second half of the motor winding in parallel with the first half of the motorwinding.

Advantages1. Starting current is approximately 60 to 65% of the value encountered if the motor were

started across-the-line.2. Starting torque is approximately 45 to 50% of the value encountered if the motor were

started across-the-line.3. Continuous connection of motor-to-line during transition periods minimizes voltage

fluctuation during the transition period.4. Can be applied to most 4, 6 and 8 pole motors.




Starting Methods

Increment Starting

2. Wye-Delta Starting

GeneralWye-Delta starting is a method of increment starting used with a three phase A.C.

induction motor to reduce the initial values of motor starting current and torque, compared tothose values obtained with across-the-line starting. Both ends of each phase winding arebrought into the motor conduit box. The starter is designed to connect these windings in Wye onthe first step. After a preset time delay, the starter will disconnect from the Wye configurationand reconnect in Delta for continuous operation.

The voltage impressed across each phase of the motor winding during the first step (Wyeconnection) of a Wye-start Delta-run motor is lower than the voltage, which would be impressedacross each phase of the motor if across-the-line starting were used. This lower voltage results inlower starting current and torque (refer to Figure 7.3 below).

Three phase A.C. induction motors, having Wye-Delta winding connections, are popularin Europe because supply voltages of 220 and 380 are used. Motors wound for 220/380 voltsmay be started across-the-line on either 220 or 380 volts or may be operated at Wye-start Delta-run on 220 volts.

OperationTwo types of Wye-Delta starters are used, the open-circuit transition and the closed-

circuit transition types. Both types connect the motor windings in Wye on the first step. After apredetermined time interval, the timer causes the starter contactors to reconnect the motorwindings in the Delta or “run” connection.

Advantages:1. Starting torque per starting amp ratio equal to that of the across-the-line starter.2. Starting current is reduced to approximately 33% of the values encountered if the motor

were started across-the-line.3. Soft start - Starting torque is approximately 33% of the value encountered if the motor

were started across-the-line. This low starting torque is often desirable to softlyaccelerate loads having high inertia and low retarding torque (Example - centrifuges andunloaded compressors). The low starting current during the starting period allows themotor to withstand a longer acceleration time than an equivalent sized across-the-linestart motor. The Wye-Delta motor; however, will accelerate with only slightly moreinertia than the across-the-line motor since the thermal capacity of both motors is thesame. To accelerate a specific inertia, the




Starting Methods

Increment Starting – cont.

2. Wye-Delta Starting – cont.

Wye-Delta motor will produce a lower temperature rise within the motor than anequivalent size across-the-line start motor because the longer acceleration timeallows the heat in the motor to be efficiently dissipated to the housings and surroundingatmosphere.

4. Can be adapted to most 2, 4, 6 and 8 pole motors.5. May be started as frequently as an across-the-line start motor if the retarding torque of

the load is negligible.6. Limited motor noise and vibration during starting.7. On the open-circuit transition type, no resistors are required.8. On the closed-circuit transition type, voltage fluctuation during the transition period is

minimized.

Caution:1. Motor started on Wye connection and operated on the Delta connection must be

specifically designed for Wye-Delta. Motors rated 4000 volts and higher are usually notsuitable for Wye-Delta starting.

2. The motor will not start if the torque demanded by the load exceeds that developed bythe motor on the Wye connection. When the motor is connected in Delta, normal startingtorque is available to start the load.

3. The transfer from Wye to Delta should be delayed until the motor speed is high enoughto ensure the current change during switching will not exceed power sourcerequirements. Generally, the starter time should be set so switching from Wye to Deltaoccurs at 80-90% of full load speed.

4. On the open-circuit transition type, line voltage fluctuation can result during thetransition period due to sudden current changes.

SummaryTable 7.1 summarizes, in chart form, the motor starting performance with these various startingmethods.

To this point, we have reviewed these various starting methods and their effect on inrushcurrent, line current and starting torque. Our major concern is how to get the motor started andup to speed as rapidly as the load permits. Figure 7.4 shows why this is necessary. This is atypical speed-current curve, and illustrates how inrush current remains high throughout most ofthe accelerating period.




Starting Methods

Increment Starting – cont.

2.Wye-Delta Starting – cont.

If the power system on which this motor is to operate cannot stand this inrush at fullvoltage, and a means of reduced voltage or increment start is elected, then we must be aware ofthe effect on current and torque as displayed in Table 7.1 below. Keep in mind the motor doesnot recognize the type of starter being used. It interprets what is received at the motor terminalsas applied voltage, which appears at the shaft as a torque to be overcome. It is recognizing twofactors; voltage and load torque.

An increasing number of specifications are being written which state the motor must becapable of starting with 90%, 80% or 70% voltage, and must also be capable of momentaryoperation with a voltage dip to 90%, 80%, or 70% voltage. This introduces three points forconsideration.

1. Will the motor develop enough torque at start to initiate rotation of the load?2. Will the motor be capable of maintaining rotation during the accelerating period?3. Will the motor have sufficient torque to sustain rotation during periodic voltage dips?

Figure 7.5 below displays a family of motor speed torques for terminal voltages of 100%, 90%,80% and 70% rated voltage. The speed torque requirement of a centrifugal pump is also shownas a typical load curve.

1. The motor will break away and begin rotating as long as more torque is generated atlocked rotor than the load requires. In this example the motor will start under any one ofthe four voltage conditions.

2. As long as the motor is generating more torque than required by the load the motor willcontinue to accelerate. This will continue until the torque developed by the motor isequal to the torque required by the load. Acceleration will stop and the motor willattempt to operate the driven device at this speed. If the speed is too low for the drivendevice, the torque condition of either the motor or the driven device must be changed toincrease the speed to an acceptable value.

3. When the voltage dip occurs, the motor performance will be in accordance with thespeed torque curve for this reduced value. The motor will continue to operate as long asthe intersection of the load curve and the motor speed torque curve occurs above thebreakdown torque point of the motor. The closer this operating point gets to thebreakdown point, the quicker the motor will overheat, thus reducing the time the motorcan successfully withstand the voltage dip.




Starting Methods

Figure 7.3. Sequence of Operation Open Circuit Transition

Step #1: Contactor(s) Closes,Connecting Motor Windingsin Wye.

Step#2: Contactor (IM) Closes,Connecting the WyeConnected Motor to the Line(Wye Starting).

Step #3: Contactor(s)Opens, Breaking Wye PointConnection. Contactor (IM)Remains Closed.

Step #4: Contactor (2M)Closes Connecting MotorWindings in Delta to the Line(Delta Running).




Starting Methods

Table 7.1. Reduced Voltage Starting

Autotransformer* Primary Resistance Reactor

50% 65% 80%tap tap tap

60% 80%tap tap

50% 65% 80%

Starting current drawnfrom line as % of that

which would be drawnupon full-voltage starting.

25% 42% 64% 65% 80% 50% 65% 80%

Starting torque developedas % of that which would

be developed on full-voltage starting.

25% 42% 64%Increase slightly with

speed.

42% 64%Increase greatly with

speed.25% 42% 64%

Smoothness ofacceleration

Second in order ofsmoothness.

Smoothest of non-programmable reduced-voltage types. As motor gains speed, current

de-creases. Voltage drop across resistor orreactor decreases and motor terminal voltage

increases.

Allowable acceleratingtimes (typical).

30 seconds based onNEMA medium duty

transformers

5 seconds Based onNEMA Class 116

Resistors

15 seconds basedon medium duty

reactors

Starting current andtorque adjustment.

Adjustable within limits of various taps.

Equipment3 contactors, timer and

starting element.Two contactors, timer and starting element.




Starting Methods

Table 7.1 cont. Reduced Voltage Starting

Part Winding Wye (Star)-Delta Solid StateAdjustable

Frequency Drive2-Step 3-Step

Starting currentdrawn from line

as % of thatwhich would bedrawn upon full-voltage staring.

50%" 25%" 33-1 /3%

Adjustable and loaddependent. Requiressufficient voltage and

current to developtorque to accelerate

load.

Adjustable. Typically150 percent of rated

current foracceleration of

centrifugal loads.

Starting torquedeveloped as %of that which

would bedeveloped onfull-voltage

starting.

50%" 12-1 /2%" 33-1 /3%

Varies approximatelyas square of ratio ofimpressed voltage torated voltage times

torque at ratedvoltage

Adjustable. Can be ashigh as motor's

breakdown torque,dependent on drivemaximum current

capacity.

Smoothness ofacceleration

Fourth in orderof smoothness.

Third in order ofsmoothness.

Smooth ( Stepless )

Smoothest of allstarting methods.

Rate of speed increasecan be programmed,

highest torque tocurrent ratio of any

starting method.

Allowableaccelerating

times (typical).

2-3 secondsLimited by

motor design

45-60 second.Limited by motor

Typically limited to30 seconds at 500 -600 percent current

with standardstarters. Varies withstarter model and

manufacturer

No limit whenaccelerating within

drive overload currentcapacity

Starting currentand torqueadjustment.

Fixed Programmable

Equipment

Two contactorsand timer.Element

inherent inmotor

3 contactors andtimer on opentransition. 4

contactors, timerand resistor on

closed transition.Starting elementinherent in motor

design

Low voltage control system; Line and bypasscontactors




Starting Methods

Figure 7.4. Typical Speed vs. Current Curve for Squirrel Cage Induction Motors




Starting Methods

Figure 7.5. Typical Speed vs Torque Curves for Low Terminal Voltage Squirrel Cage InductionMotors




Starting Methods

Motor Starters and Schematic Diagrams

Many standard (stock) dual voltage motors are designed and built to be suitable foroperation on part winding start on the lower voltage. The standard motor may be a star or deltaconnected unit and the type of motor connection employed must be considered when selectingthe starter type.

There are two types of starters which may be used for part winding starting, the 4-2 and3-3 types. Both starter types have two contactors; however, the 4-2 has one four pole and onetwo pole contactor; whereas the 3-3 type has two three pole contactors. It is possible to useeither starter type regardless of motor connection (Star or Delta) or whether it is built for singleor dual voltage operation. The 4-2 type starter characteristics make it the most flexible of thetwo starter types; however, the 3-3 type starter is presently the most popular, since it is a NEMAdefined starter.

External connection diagram 51-676-394 shows a typical dual voltage (230/460) motorconnection. Diagram 51-688-230 shows how this motor can be used with part winding start onthe low voltage (230V) rating. For part winding start on 460 volt, or other than 230 volt, themotor must be wound specifically for the intended voltage. It would have a six lead connectionand 51-406-529 is typical (see Section 5).

Caution:1. Motor to be part winding started must be designed and built properly to ensure that two

parallel stator windings are provided.2. The motor will not start if the torque demanded by the load exceeds that developed by

the motor on the first step or when 1/2 of the motor winding is energized. When thesecond half of the winding is energized, the normal starting torque (same as across-the-line starting) is available to accelerate the load.

3. By use of two step part winding starting, the inrush current is divided into two steps, thusproviding the power source’s line voltage regulators with sufficient time to compensatefor the voltage drop caused by motor starting.

4. Motor heating on first step operation is greater than what is normally encountered onacross-the-line start. Therefore, elapsed time on the first step of the part winding startshould not exceed three seconds.

5. When the first half of the winding is energized, a slight increase in electrical noise andvibration may be encountered.




Duty Cycles and Inertia

Horsepower Variations

Many machines work on a definite duty cycle that repeats at regular intervals. If thevalues of power required during the cycle, and the length of their durations are known, therating of the motor required can be calculated by the root-mean-square (RMS) method.

Multiply the square of the horsepower required for each part of the cycle by the durationin seconds. Divide the sum of these results by the effective time in seconds to complete thewhole cycle. Extract the square root of this result. This gives the RMS horsepower. If the motor isstopped for part of the cycle, only 1/3 of the rest period should be used in determining theeffective time for open motors (enclosed motors use 1/2 of the rest period). This is due to thereduction in cooling effect when the motor is at rest.

Example:Assume a machine operation, where an open motor operates at an 8 HP load for 4 minutes, 6 HPload for 50 seconds, 10 HP load for 3 minutes, and the motor is at rest for 6 minutes.

=(8 × 240) + (6 × 50) + (10 × 180)

240 + 50 + 180 + 3603

= √59.6 = 7.7

Use 7.5 HP motor

For fast repeating cycles involving reversals and deceleration by plugging, the additionalheating due to reversing and external WK2 must be considered. Consequently, a more elaborateduty cycle analysis is required. It is necessary to know the torque, time, and motor speed foreach portion of the cycle, such as acceleration, running with load, running without load,deceleration, etc.

For such detailed duty cycles it is sometimes more convenient to calculate on the basis oftorque required rather than on the horsepower basis.





Accelerating Time

, . =× ( ℎ )

308 × . ( − )

The above formula can be used when the accelerating torque is substantially constant. Ifthe accelerating torque varies considerably, the accelerating time should be calculated inincrements: the average accelerating torque during the increment should be used and the size ofthe increment used, depends on the accuracy required. The following equation should be usedfor each increment:

, . =×

308 × ( − )

WK2 = moment of inertia, lb-ft2 of system (motor + load)RPM = motor speedTL = motor torque, lb-ft at a given speedT = load torque, lb-ft at the same speed

Moment of Inertia (WK2)

The moment of inertia is used for calculating the accelerating time of the motor and itsload. The moment of inertia of a rotating body is the weight of the body times the radius ofgyration squared. The mass of the body as actually distributed around the center of rotation isequivalent to the whole mass concentrated at a certain radius “K”, called the radius of gyration,from the axis of rotation. The radius of gyration “K” depends upon the shape of the object andthe axis of rotation. An unsymmetrical object will have a different “K” depending upon theorientation of the axis of rotation. In the formula for calculating “accelerating time” the WK2

product of weight (W) and the square of the radius of gyration (K2), appears. This will hold truein any formula whenever the moment of inertia is of concern.

Formulas for the moment of inertia (WK2), based on specific weights of metals, can befound in Table 7.2 below and the results seen in Table 7.3.

Table 7.2. Weights of MetalsWeights of Metals

(lbs./in.3)Magnesium 0.0628Aluminum 0.0924Iron 0.260Steel 0.282Copper 0.318Bronze 0.320Lead 0.411





Calculation of Inertia of Shafts

To determine the WK2of a solid shaft, use the following formula:

= 170.4( )

Where WK2 = inertia (lb-ft2)w = specific weight of shaft material (lb-in3)L = length of shaft (ft)D = diameter of shaft (ft)

To determine the WK2of a hollow shaft, use the following formula:

= 170.4 × × ( − )

Where WK2 = inertia (lb-ft2)w = specific weight of shaft material (lb-in3)L = length of shaft (ft)D2 = outer diameter of shaft (ft)D1 = inner diameter of shaft (ft)





WK2 of Steel Shafting and Disc

To determine the WK2 of a given shaft or disc, multiply the WK2, given below, by thelength of the shaft or thickness of disc, in inches. To determine inertias of solids of greaterdiameter than shown below, multiply the nearest tenth of the diameter by 104 or move decimalpoint four places to the right and multiply by the length. For hollow shafts, subtract WK2 ofinside diameter from WK2 of outside diameter, then multiply by length.

Table 7.3. WK2 Values Per Inch of Length or ThicknessDiameter WK2 Diameter WK2 Diameter WK2

(Inches) (Lb. Ft.2) (Inches) (Lb. Ft.2) (Inches) (Lb. Ft.2)0.75 0.00006 10.50 2.35 32 201 .81.00 0.0002 10.75 2.58 33 228.21.25 0.0005 11.00 2.83 34 257.21.50 0.001 11.25 3.09 35 288.81.75 0.002 11.50 3.38 36 323.22.00 0.003 11.75 3.68 37 360.72.25 0.005 12.00 4 38 401 .32.50 0.008 12.25 4.35 39 445.32.45 0.011 12.50 4.72 40 492.83.00 0.016 12.75 5.11 41 543.93.50 0.029 13.00 5.58 42 598.83.75 0.038 13.25 5.96 43 658.14.00 0.049 13.50 6.42 44 721.44.25 0.063 13.75 6.91 45 789.34.50 0.079 14.00 7.42 46 861 .85.00 0.12 14.25 7.97 47 939.35.50 0.177 14.50 8.54 48 1021 .86.00 0.25 14.75 9.15 49 1109.66.25 0.296 15.00 9.75 50 1203.16.50 0.345 16.00 12.61 51 1302.26.75 0.402 17.00 16.07 52 1407.47.00 0.464 18.00 20.21 53 1518.87.25 0.535 19.00 25.08 54 1636.77.50 0.611 20.00 30.79 55 1761 .47.75 0.699 21.00 37.43 56 1898.18.00 0.791 22.00 45.09 57 2031 .98.25 0.895 23.00 53.87 58 2178.38.50 1 .000 24.00 63.86 59 2332.58.75 1 .13 25.00 75.19 60 2494.79.00 1 .27 26.00 87.96 66 3652.59.25 1 .141 27.00 102.3 72 51729.50 1 .35 28.00 118.31 78 71259.75 1 .75 29.00 136.14 84 9384

10.00 1 .93 30.00 135.92 90 1262910.25 2.13 31.00 177.77 96 16349





High WK2 Acceleration

When starting a high WK2 load, step-starting may be required to maintain the torquenecessary to accelerate the mass. Care must be taken in choosing resistor capacity to dissipatethe heat resulting from the starting current.

To determine the correct motor for a high WK2 load the following information is needed:1. WK2 of load2. Torque required3. Duty cycle

Example:200 lbs-ft for 5 seconds accelerates load to 1150 rpm; 50 lb-ft for 10 seconds does workrequired; 200 lbs-ft for 5 seconds decelerates load to standstill; 12 seconds at rest (1/3 of off-time is used for open motors).

= 5 + 10 + 5 +123

= 24

=(200 × 5) + (50 × 10) + (200 × 5)

24= 133.1

= × 1150

5250= 29.15

Therefore, use a motor rated at 30HP and 1150 rpm.NOTE: The above example is calculated on the basis of RMS torque rather than RMS HP. Theadditional heating due to the nature of the duty cycle has been taken into consideration.





Information Required for Proper Selection

It is recommended that the factory be supplied with the following information:1. Load WK2 motor shaft.2. Number of starts, stops or reversal per unit of time.3. HP load and length of each operating period.4. Length of standing idle periods.5. Method of stopping.6. Special torque requirements of motor, such as need to break away heavy friction load

from rest; need to bring heavy inertia load up to speed (or down to stop) in specifiedperiod of time; need to have high pull-out torque to carry momentary overloads.




Special Applications

Accelerating Rotary Compressors and Vacuum Pumps

This type of machine is unique because it usually requires full load torque at 25 to 30%speed when started under full load conditions. This poses serious acceleration problems forelectric motors since high torque demand of the load occurs at the point where a motor has theleast available accelerating torque, which is the pull-up point in the motor speed/torque curve.Normal torque motors will not accelerate load. These motors are available at custom built pricingand should be used for these applications.

The following information is necessary when a fan or blower Drive is the application:· HP· RPM· Phase/Hz/Volts· Enclosure· Temperature Rise· Service Factor· WK2 at motor speed or WK2 at fan speed

In addition, the following questions should be addressed:· Dampers closed at start?

o If yes, what % HP at full speed?· Across the line (full voltage) start?· Reduced voltage start?

o If yes, % voltages tap?o In-rush kVA specified?o Max. acceleration time specified?

Note: We do not recommend Part Winding or Wye Delta starting for fans or blowers.




Special Applications

Motors for Cutting Water Pumps for Decokers

This application requires two pole motors, generally in the range of 1500 HP to 2500 HP,driving multistage horizontal high pressure pumps. The only difficult aspect of this application isthe fairly frequent requirement for repetitive starts in excess of NEMA standards, particularlyduring start-up of the system. For this application, we find that in most cases our standarddesigns can meet the application requirements. The system is set up with a bypass for starting,reducing the torque requirement during acceleration to approximately 1/4 the design load,which is an important consideration in motor sizingand should be defined in the quiet stage.

The limiting factor for two pole motors, in applications requiring frequent starting, is theheat dissipation capability of the rotor. Most of the energy required to accelerate the pump mustpass through the rotor, and, since a two pole rotor is much smaller than lower speed rotors, heatdissipation is a serious consideration. We have standard rotor designs with die cast aluminum orinduction- brazed copper alloy cage construction, which allows starting frequency at least doubleNEMA standards with normal pump WK2. With complete application information we can furnishdesigns to meet all requirements for driving cutting water pumps.




Formulas and General Data

Determination of HP Requirements

The horsepower required can be determined from the factual information or powerrequirements for specific operations. Where the force or torque required is known, one of theequations below may be used to calculate the horsepower required by constant loadcharacteristics.

Power for Translation

000,33min.*.)( perftlbsForceHP =

Power for Rotation

5250*.)( RPMlbsForceHP =

Power to Drive Pumps

OfPumpEffavitySpecificGrFrictionIncTotalHeadPerMinGalHP

.3960).(..

´´´

=

Where friction head (ft.) = pipe length (ft.) x velocity of flow

.)(367.502.0)( 2

indiameterfps´

´

Power to Hoist a Load

000,33sin.)( q´´

=FeetPerMinlbsWeightHP

q = Angle of hoist with horizontal

Power to Hoist a Load

EfficiencyinessureWaterGaugeGasPerMinFtCuHP

´´

=6350

.)(Pr...

Efficiencies for fans range between 50 and 80 percent.




Formulas and General Data

Table 7.4. NEMA Code letter designation classifying motors by ratio of locked rotor/HPNEMA Code Letter kVA/HP with locked

rotorNEMA Code Letter kVA/HP with locked

rotorA 0 – 3.14 L 9.0 - 9.99B 3.15 – 3.54 M 10.0 – 11.19C 3.55 – 3.99 N 11.2 – 12.49D 4.0 – 4.49 P 12.5 – 13.99E 4.5 – 4.99 R 14.0 – 15.99F 5.0 – 5.59 S 16.0 – 17.99G 5.6 – 6.29 T 18.0 – 19.99H 6.3 – 7.09 U 20.0 – 22.39J 7.1 – 7.99 V 22.4 – and upK 8.0 – 8.99

Table 7.5. Formulas to find amperes and Kilowatts

To Find Three Phase

Amperes when HP is known

Amperes when KW is known

Amperes when KVA is known

Kilowats Input

Kilovolt Amperes

Horsepower Output

KVA per HP

PFEffEHPI

´´´´

=.73.1

746

PFEKWI´´

´=

73.11000

EKVAI

´´

=73.1

1000

100073.1 PFIEKW ´´´

=

100073.1 IEKW ´´

=

1000.73.1 PFEffIEKW ´´´´

=

10003/

´´´

=HP

VLRAHPKVA




Formulas and General DataTable 7.6. Variables and their corresponding definitions

The relationship between frequency and number of poles to horsepower:

=120 ×

The relationship between horsepower, torque and speed:

= ×

5250

Motor Slip:

% = − × 100

Three Phase locked rotor current (IL) from nameplate data:

=577 × ×

Rules of Thumb (Approx.)• At 3600 RPM a motor develops 1.5 lb.ft. per HP of torque at Rated HP Output.• At 1800 RPM a motor develops 3 lb.ft. per HP of torque at Rated HP Output.• At 1200 RPM a motor develops 4.5 lb.ft. per HP of torque at Rated HP Output.• At 900 RPM a motor develops 6 lb.ft. per HP of torque at Rated HP Output.• At 575 RPM a 3 phase motor draws 1 amp per HP at Rated HP Output.• At 460 RPM a 3 phase motor draws 1.25 amp per HP at Rated HP Output.• At 230 RPM a 3 phase motor draws 2.5 amp per HP at Rated HP Output.

Variable DefinitionPF Power factor as a decimalEFF Efficiency as a decimalT Torque in pound-feet (lb-ft)f Frequency in cycles per second (Hz)I Current in amperesE Voltage in voltsKW Power in kilowattsKVA Apparent power in kilovolt-amperesHP Output in horsepowern Motor speed (RPM)ns Synchronous speed (RPM)p Number of poles




Adjustable Frequency Drive

An adjustable frequency drive (AFD) is an electronic device that delivers a combination ofvoltage and current, at a selected frequency, to an AC squirrel cage induction motor in order todevelop a desired torque at a certain speed to drive the connected load effectively. Terms, whichare sometimes used interchangeably to describe these devices are: adjustable frequency drive(AFD), adjustable frequency controller (AFC), adjustable speed drive (ASD), or variable frequencydrive (VFD).

AFDs convert utility sine wave power to DC (converter section) and then switch it back toAC (inverter section). A DC link is the intermediate section between the converter and invertersections. The most common type of inverter design currently used is pulse-width modulated(PWM). A PWM drive creates a wave with several positive and negative segments of varyingwidths, on each of the three phases, to form a cycle.

Advances in power electronic devices have allowed PWM drives to come into pre-dominance in recent years. Switching devices, most commonly used in the inverter section ofPWM drives, are GTO’s (gate turn-off thyristors) and IGBT’s (insulated gate bipolar transistors).The IGBT provides the capability of high switching frequencies with low power consumption,resulting in smaller, less expensive drives and better motor performance. Earlier generation AFDsused voltage-source inverters (VSI), current-source inverters (CSI), and variable-voltage inverters(VVI). These drives usually provide voltage or current to the motor in 6, 12, or 18 pulses percycle.

An AC squirrel-cage induction motor is designed to be energized by a symmetrical sinewave power source that is commonly encountered on constant frequency sources such as thatwhich electric utilities supply. When an AFD is the power source to the motor it subjects themotor to wave shapes other than true sinusoidal. Output from the AFD consists of a series ofvoltage pulses, which results in motor performance when combined. Approximating theperformance is done by a sine wave. The increased harmonic content of this non-sinusoidalwaveform, combined with the reduced cooling effect caused by the motor running at speedslower than its 50/60 hertz rated speed, will cause an increase in temperature rise if the motor isrun at constant torque.





Types of Loading: Variable/Constant Torque and Constant Horsepower

Many of our standard AC squirrel-cage induction motors operate successfully withadjustable frequency drive systems. In order to properly design and/or size a motor, thefollowing must be defined:

(a) Variable Torque Loading

This type of loading is typical of centrifugal-type loads such as pumps, compressors, andfans. Since the load power varies with the cube of speed, motor losses decrease more rapidlywith speed than cooling does, due to decreased ventilation. Therefore, no special de-rating orenhancements of the motor ventilation are necessary for continuous operation at reducedspeeds.

(b) Constant Torque Loading

This type of loading is typical with reciprocating compressors and pumps, screwcompressors, positive displacement pumps, conveyors, extruders, crushers, grinding mills, andmixers. With constant torque loading, the torque required by the load is constant over the entirespeed range. The current/copper losses are essentially unchanged at all speeds and the total heatproducing losses do not significantly diminish with speed. Therefore, the motor temperature willincrease with decreased speed. To overcome this, the motor must be de-rated or the coolingmust be enhanced with an auxiliary blower capable of delivering constant cooling over theentire operating range.

(c) Constant Horsepower Loading

This type of loading is typical of tension reels, winders, hoists, traction motors, machinetools, and mill stands. During constant horsepower loading the torque required by the drivenequipment increases with decreasing speed. Motors must be sized to deliver the requiredhorsepower at base speed without overheating or over saturating the motor’s magnetic material,and also to deliver the required horsepower at maximum speed, along with any requiredoverload conditions.Consult the factory for constant horsepower applications.





Operating Range

Expressed in RPM, frequency, or both. Assume constant volts per hertz up to base motor designfrequency. Assume constant horsepower above base motor design frequency. The basefrequency need not be the frequency supplied by the electric utility. For example, a 600 RPMbase speed may be met with an 8 pole motor operating at 40Hz. The use of 2-pole motors withvariable frequency drives has increased dramatically in the last several years. One application ofparticular interest to Norwood is the retrofitting of gas turbines with motor/drive packages forthe pipeline industry. The speed range of a typical pipeline application is 1400 – 3600 rpm. Inorder to meet this complete speed range, without “blocking out” a potentially-desired speed, themotor must have a rigid shaft design.

A motor with a rigid shaft design has a first critical speed which is higher than the motor’soperating speed, or one which is critically-damped near or below operating speed, thus enablingoperation at any speed appropriately removed from the un-damped critical speed. In the past,motor manufacturers did not provide large, 2-pole motors with rigid shafts, due to the high costof design and manufacturing processes.

A motor with a flexible shaft design has a first critical speed which is lower than themotor’s operating speed. If the critical speed falls within the desired speed-range, the user must“block out” this critical area, or face the possibility of having extreme vibration levels, putting theentire drive-train in jeopardy.

First Critical Speed - When the motor is operating at its resonance frequency. Resonancefrequency creates vibrations which can destroy motors.

Blocking Out - The Variable Frequency Drive (VFD) is programmed to not allow themotor to continually operate at its critical speed. The VFD will accelerate quickly throughthe critical speed to limit the time the motor operates at the dangerous speed.

Critically-damped – Safe operating speed for a motor due to very low vibrationamplification.

Table 7.7 below provides an overview of Norwood-built, AboveNEMA standard andoptional shaft design capabilities for 2-pole and 4-pole motors. “Max HP” is based on 80°C rise byresistance at 1.0 SF, 40°C ambient, 4000V, Full Voltage Starting. Actual Motor HP to depend onrequired temperature rise, ambient, voltage and starting requirements. All units are SleeveBearing, Fabricated Copper Bar Rotor Design.





Operating Range – cont.

Table 7.7. Standard and Optional Shaft Design Capabilities

Frame

Motor Enclosure

Speed Rotor DescriptionODP/WPII(Max HP)

TEWAC(Max HP)

TEAAC(Max HP)

TEFC(Max HP)

508 800 3600 Stiff Shaft; Highly Damped5010 1,250 3600 Stiff Shaft; Highly Damped509 450 3600 Stiff Shaft; Highly Damped

5011 600 3600 Stiff Shaft; Highly Damped5013 800 3600 Stiff Shaft; Highly Damped588 900 1,250 800 3600 Stiff Shaft; Highly Damped

5810 2,000 2,000 1,250 3600 Stiff Shaft; Highly Damped5812 2,500 2,500 1,750 3600 Stiff Shaft; Highly Damped588 600 3600 Stiff Shaft; Highly Damped

5810 900 3600 Stiff Shaft; Highly Damped5812 1,000 3600 Flexible6811 3,000 3,000 2,250 3600 Stiff Shaft; Highly Damped6813 5,000 5,000 4,000 3600 Flexible

6813 -Option 5,500 5,500 4,000 3600

Stiff Shaft; Highly Damped(Fluted)

8010 5,500 5,500 5,000 3600 Stiff Shaft; Highly Damped8010 -Option 7,500 7,500 6,500 3600

Stiff Shaft; Highly Damped(Fluted)

8012 9,000 9,000 7,000 3600 FlexibleSH400 1,100 3600 FlexibleSH450 1,500 3600 Flexible

880 2,000 3600 FlexibleSH500 2,000 3600 FlexibleSH560 3,000 3600 FlexibleSH630 10,000 10,000 6,000 3600 FlexibleSH710 18,000 18,000 14,000 3600 FlexibleSH630 11,000 11,000 7,000 1800 True StiffSH710 18,000 18,000 10,000 1800 Stiff Shaft; Highly Damped





Operating Range – cont.

Consult the factory on all 2-pole applications. The Norwood factory offers “stiff shaft”designs as standard for 2 pole motors on frames 5812 and smaller. Stiff shaft 2 pole designs canbe built on 6811, 6813 frames and 8010 frames with special shaft and rotor laminationconstruction. For 2 pole AFD applications where it is not possible to supply a stiff shaft design, itwill be necessary to take precautions to avoid continuous operation in speed ranges near thecritical speed. These precautions must be coordinated with, and be acceptable to, the customer.

Consult the factory on all 4-pole applications above 75Hz.

Torque Requirement

Expressed as the torque value, values required at a particular speed, or throughout theoperating speed range. It’s usually expressed as the base (sinusoidal) HP and RPM of the motorrequired.

It is recommended the size of the motor’s base rating not exceed 80°C by resistance, atfull load, on a 60Hz sinusoidal input and utilize class F insulation for additional heating caused bythe AFD application. Depending upon the application and motor enclosure required, dissipationof this excess heat must be considered.

Note: Explosion-proof/dust ignition-proof enclosures are currently not U/L listed for use on AFDapplications.





For a variable torque application, where the torque varies as the square of the speed, astandard 80°C rise unit in any enclosure could be utilized for operation from 6 to 75Hz. For aconstant torque application, where the torque is required throughout the speed range, sizingand enclosure options are more restrictive. Depending on the enclosure construction,compensation for heat addition/dissipation can be accomplished by de-rating (over sizing) themotor, adding an auxiliary blower, or both. In addition, a special rotor design may be necessary.Torque de-rating factors for TEFC and Open motors are shown below in Figures 7.6 and 7.7.Solid curves are self-ventilated, dashed curves are auxiliary ventilated.

Figure 7.6. Torque multipliers for TEFC Motors vs Frequency





Figure 7.7. Torque Multipliers for Open Motors vs. Frequency




Adjustable Frequency DriveOther Considerations

1. Insulation System

(a) Voltage Spikes

A motor driven by an adjustable frequency drive is subjected to significantly larger peakvoltage rates as opposed to a sine wave voltage supply. Modern power semiconductor devices,such as insulted gate bipolar transistors (IGBT), feature faster switching cycles and steep edgesof the width-modulated voltage pulses. The switching times are now commonly less than 1microsecond with voltage rate of changes up to extremes of 10 kV/µs. This is very stressful to theinsulation system. In particular, on our random wound motors, the 600-volt insulation systemmaximum peak voltage (voltage spike) must not exceed 1300 volts line to line. If this isexceeded, a higher voltage class insulation system would need to be supplied; resulting in highercost due to a change in motor frame size.

(b) Neutral Shift

On a balanced three-phase sinusoidal voltage supply, an induction motor’s neutral will beat or near ground potential. Line-to-ground RMS voltage level will be equal to line-to-line RMSvoltage divided by 1.732. AFDs can expose the motor windings to higher than normal line-to-ground voltages due to the neutral shift effect, where there is a voltage difference between themotor neutral and the source neutral. For current source inverters the line-to-ground voltage,resulting from the neutral shift effect, can be as high as 3.3 times the crest of the nominalsinusoidal line-to-ground voltage. For voltage source inverters the line-to-ground voltage can beas high as 1.732 times the crest of the nominal sinusoidal line-to-ground voltage.

Neutral shift can be reduced if the drive is connected to an ungrounded power source orby isolating the drive from the source ground by using an isolation transformer. This can be doneby using separate reactors in both the positive and negative direct current link or by the use ofoutput sine wave filters; with the filter’s neutral point solidly grounded.

If measures are not taken to protect the motor from over voltages associated with neutralshift, the insulation system of the motor must be upgraded by specifying a higher voltage classto accommodate the maximum expected line-to-ground voltage. In addition to the cost impactof the higher voltage insulation system, there may also be a frame size increase due to reducedavailable space for copper in the stator winding.





1. Insulation System - cont.

Table 7.8. Stator Insulation Level for Motors Operated with IGBT DrivesSystem

Voltage (V)Ground Insulation System Turn InsulationFiltered

Output/ Non-IGBT

UnfilteredOutput (V)

FilteredOutput/ Non-

IGBT

Unfiltered Output (V)

601 – 1400 Standard 2400 Standard HPAVSDG ifT/C≥0.00641*VSystemor Mica

1401 – 1900 Standard 4200 Standard Mica, T/C≥31901 – 2400 Standard 5500 Standard Mica, T/C≥32300 Standard 4200 Standard Standard, T/C≥33300 Standard 5500 Standard Mica, T/C≥54160 Standard 7200 Standard Mica, T/C≥66600 Standard 10000 Standard Mica, T/C≥6NOTE: The ground insulation system assumes that precautions are taken against continuousoperation with the neutral shifted significantly from ground potential. If the neutral is allowed toshift significantly from ground potential, the ground insulation needs to be upgraded in thesame manner as for sinusoidal ungrounded power systems.





2. Cable Length

Inverters produce peak voltages approximately 1.5 times the nominal voltage of thenominal supply voltage, compared to 1.4 for a sinusoidal power supply. In reality, the amplitudeof voltage peaks can be even greater. This is due to the impedance mismatch between the cableand motor, combined with long cables connecting the motor and drive. The AFD pulses can actlike impulse waves on the motor cables, resulting in reflection phenomena. This causes the peakvoltage at the motor to be increased up to a theoretical limit of two times. Therefore, it isrecommended that the cable length between the motor and drive be limited to fifty (50) meters,or that the drive be supplied with a dv/dt filter on the drive output.

3. Insulated Bearings

The AFD can induce voltages greater than 0.5 volts into the motor shaft and bearings.This can cause shaft currents that result in many tiny pits forming in the bearing or shaftsurfaces, ultimately causing failure. These shaft currents may not show up on a sinusoidalsystem. AFDs may be generators of a high frequency, short rise time, and common modevoltage. Common mode voltage may be coupled to the rotor, via parasitic capacitances betweenthe stator winding and the rotor, causing the rotor potential to be as much as 10 to 40 voltsfrom ground. This common mode voltage causes current to flow from the stator winding toground, via parasitic capacitances between the winding and ground, and then through theground circuit back to the control. These currents generate a circular time varying magnetic flux,which induces shaft end-to-end voltages. To protect the motor’s bearings and prevent damage toother shaft connected equipment it is necessary to insulate both bearings and supply a shaftgrounding brush; or the drive must be supplied with a common mode filter on the drive output.A 2.5-inch increase in the “BA” dimension is required for motors with drive end shaft groundingbrushes. If the grounding brush is not provided on the drive end, an insulated coupling must beutilized to protect non-insulated bearings in the driven equipment.

NOTES:A. Motors with shaft grounding brushes cannot be used in hazardous locations.B. Shaft-grounding brushes cannot be supplied for V-belt drive applications.C. Consult factory for motors with P, C, and D flanges.





Siemens Norwood IGBT Policy Statement

Despite many studies and publications on the topic of shaft current related bearingdamage, there is still no conclusive information available that serves to quantify the manyvariables involved. Due to this lack of knowledge, there is no known method for predictingproblems in advance of an installation, or industry accepted guidelines, to follow. In order toprotect Norwood from the risk of potentially huge warranty costs, and avoid exposing ourcustomers to a risk that they may not be aware of, the following bearing policy statement wasdrafted and agreed upon by the Norwood Large Motor Products Plant and Siemens Systems:

Policy Statement: IGBT/BRGSiemens Norwood AC Induction MotorsIGBT Control Induced Bearing Currents

Siemens has had considerable, successful experience operating motors in the field inapplications that utilize IGBT type adjustable frequency controls. Throughout the industryhowever, a few variable frequency control applications and installations have been shown toproduce currents in the bearings of motors they control. Siemens Drives and Siemens Systemsgroups have the expertise and experience necessary to ensure that your installation is configuredsuch that problem free operation is attained. However when Siemens motors are to be used withcontrols manufactured by other companies, we defer system configuration details to that controlmanufacturer. If the application is such that a problem due to bearing currents could potentiallyoccur, one of the following solutions should be implemented with the motor and control system.

a) Use of a control output filter that reduces common mode voltage with non-drive endbearing insulated.

b) For 500 frame and larger motors, insulate the drive end and non-drive end bearingand add a shaft grounding brush. Unless the grounding brush is provided on the driveend, an insulated coupling must be utilized to protect non-insulated bearings in the loadequipment.

Motors constructed in accordance with (b) are available. Consult the motor factory for details.

Issued: 09/16/1999Revised: 05/19/2009





Marketing Quotation Guidelines

Table 7.9 outlines the bearing insulation guidelines used to quote motors for use withadjustable frequency controls:

Table 7.9 . Marketing Quotation GuidelinesDrive System Marketing QuotationSiemens Drives Rated 380 – 690 Volts One insulated bearing (NDE)Siemens MV Drives Rated 700+ Volts Two Insulated bearings and shaft grounding

brush or filtered control outputSiemens Simovert I Drives (GTO Based) One insulated bearing (NDE)Competitor IGBT Drives (380 – 700 V) Two insulated bearings and a shaft grounding

brush, or submittal and acceptance of Norwoodpolicy statement

Robicon Perfect Harmony Drive (2400 – 7200 V) One insulated bearing (NDE)Competitor IGBT Drives (2300 – 7200 V) Two insulated bearings and a shaft grounding

brush or common mode voltage filter on driveoutput

Competitor GTO Based Drives (380 – 7200 V) One insulated bearing (NDE)





Tachometers

Tachometers / encoders provide the capability of precise speed measurement and controlin AFD applications. Our standard encoder (when tachometer is requested by customer) is singleoutput, 1024 pulses per revolution, with antifriction bearing. Depending on motor enclosure andbearing type, these may be either shaft mounted or C-flange mounted. When encoders arespecified for ODP/WPII/TEWAC motors, or for any motor with sleeve bearings, a shaft-mountedencoder will be supplied.

Standard encoders:

• Shaft Mountedo Avtron M3 or M4

• C-Flange Mountedo Northstar (Formerly Lakeshore) SL85o Northstar (Formerly Lakeshore) 8500o Avtron AV850

Dual output encoders are available at additional cost. Consult the factory if the customerrequests a specific encoder not listed above.

Capacitors

The use of power capacitors for power factor correction or surge suppression on the loadside of an inverter connected to an induction motor is not recommended. Line reactors or filternetworks for inverter voltage spike suppression may be acceptable. For such applications thecontrol manufacturer should be consulted. (Reference NEMA MG-1 2016, Part 31.4.3.4)





Drive By-Pass Capability

When motors are applied with AFDs it is possible to accelerate high inertia or highstarting torque loads with a standard torque motor. The drive will be able, theoretically, to utilizethe motor’s breakdown torque during acceleration; provided the drive has sufficient currentcapacity. Since the motor’s rotor cage is not subjected to high slip frequencies when operated ona drive, the losses in the rotor cage will be several times lower at low speeds than would be seenat the same speed while operating on utility power supply. High inertia loads can be brought upto speed without over heating the cage elements or the stator winding. The motor need only besized to deliver its rated service factor horsepower and dissipate any additional heating, due tolosses caused by the drive harmonics, and to deliver sufficient breakdown torque to handle anymomentary overloads in the duty cycle.

If there is a customer requirement for drive by-pass starting capability, the motor must besized to handle the inertia and/or torque requirements of the driven equipment on utility powersupply. It may also be necessary to provide special construction of rotor cage elements. We mustbe informed of any site conditions that would impose a limit on the allowable starting current oravailable voltage, at the motor terminals during the start cycles.

Noise

A motor operated on an AFD will generally develop higher noise levels than whenoperating on sine wave power. The overall sound level will increase or decrease in parallel tospeed changes. Varying forcing frequencies dependent on many factors, which will vary withspeed, will excite structural components of the motor. In the speed range of the application thecomponents may be excited at a resonance frequency, which will cause an increase in noise. Fannoise will generally increase with increasing speed. We cannot guarantee a given sound pressureor sound power level for operation on a drive. If a sound pressure limit is required it will beevaluated on the basis of operation on a 60Hz (or 50Hz) sinusoidal supply voltage, with themotor running at no load. Consult the factory if a sound pressure limit is specified.

Top mounted auxiliary blowers can be supplied for TEFC machines. The motordesignation becomes TEAO, type CGZAO. Blower motors are dual voltage 230/460 rated at 3 HPor 7.5 HP, depending on the frame size of the motor being cooled. The blower motors can alsobe operated at 50Hz, at voltages ranging from 190V to 415V. The blower motors are suitable forClass 1 Group A, B, C, and D, Division 2 Hazardous Locations with a T3 temperature code.

Siemens Industry, Inc. Process Industries and Drives Large Drives 4620 Forest Avenue Norwood, OH 45212

usa.siemens.com/motors

Subject to change without prior notice. Order No.: ANAM-00001-0118All rights reserved. Printed in USA ©2017 Siemens Industry, Inc.

The technical data presented in this document is based on an actual case or on as-designed parameters, and therefore should not be relied upon for any specific application and does not constitute a performance guarantee for any projects. Actual results are dependent on variable conditions. Accordingly, Siemens does not make representations, warranties, or assurances as to the accuracy, currency or completeness of the content contained herein. If requested, we will provide specific technical data or specifications with respect to any customer’s particu-lar applications. Our company is constantly involved in engineering and development. For that reason, we reserve the right to modify, at any time, the technology and product specifications contained herein.

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