fire pump motor starting
DESCRIPTION
Motor Starting Techniques, Parameters and Applications.TRANSCRIPT
Induction Motors: Parameters & Starting
By: James S. Nasby -- Columbia Engineering
2C.E.
Seminar Details & Background Background (History of Seminar) National Fire Protection Association
(NFPA)
“Pumps for Fire Protection Systems”
NEMA Standard MG-1Motors and Generators
See Also: Section VIII. References Cited
3C.E.
Topics to be CoveredI. Induction Motors –
General
II. Electrical Power Supply
III. Induction Motor Parameters
IV. 3Ø Motor Starting Types (8+1)
V. 3Ø Motor Running Types (3)
VI. Common Motor Wiring Types (14)
VII. Installation Considerations
4C.E.
I. Motors – GeneralMotor Types
Induction Motors Three Phase Non-Salient Pole Motors:
Usually Squirrel Cage Rotor Motors -but- can be Wound Rotor (Slip Ring) Induction Motors
Usually Squirrel Cage Design Type: Usually NEMA Design
“B”Normal Starting TorqueNormal Starting Current (KVA)
Synchronous Motors Not Covered
5C.E.
I. Induction Motors General Definitions
Motor Poles – Even Numbers (2, 4, 6, etc.)
Synchronous Speed (No Load Speed - Slip)
Starting Region – Fixed Impedance Running Region – Energy Converter Torques:
Stall = Locked = Zero Speed TorquePull-up TorqueBreakdown TorqueRated Torque
Starting Amps, KVA & Locked Rotor Code
6C.E.
Motor Starting Region – cont’dMotor Torque Curve
Motor Torque and Pump Torque Curves
7C.E.
II. Electrical Power Supplies
Power Sources - Mains
Types of Power Source– Three Phase A.C.
Power Source Characteristics
(Parameters)– Voltage (Utilization Voltage) -at- – Low voltage or Medium Voltage– Frequency – 50 Hz or 60 Hz– Starting Voltage Drop -vs- Starter
– Running Voltage Drop -vs- Motor
8C.E.
Power Supply Characteristics – cont’d
- Power Quality - Source Capacity - Weak or Stiff
Source– Starting Voltage Drop (15% of Controller
Rated)– Running Voltage Drop (5% of Motor Rated)– Method of Calculating - NEMA ICS-14– Gen-Sets - Frequency & Voltage
Voltage Balance (Amount of Imbalance) Small Voltage "Unbalance" = Large Current
Imbalance. (See NEMA MG-1, part 1-14.36)
Voltage Harmonics (Heats Windings)
Power Factors - Affected by Motor
9C.E.
III. Induction Motor ParametersGeneral Motor Characteristics Induction Motor Types
– Wound Rotor Motor (Slip Ring Motor)= Rotary Transformer
– Squirrel Cage Motor = Ditto– But with Slip Rings Shorted
Frequency – 50 Hz -vs- 60 Hz
NEMA Design Type “B” (MG-1)
10C.E.
NEMA Design Types
Standard Three Phase
Induction Motors are
NEMA Design “B”
( Rated Full Load Torque)
Rated | Speed (RPM)
11C.E.
Induction Motors - cont’d Motor Parameters - Electrical
Locked Rotor Code (KVA per Hp) Service Factors
– Usually 1.15 Maximum Allowed– Often Higher for Smaller Motors– Usually 1.0 Max. when used with VFD's
Service Factor (S.F.) -vs- Ideal Conditions– Max. Temperature (40 °C Max.) -and-– Max. Altitude (3,300 ft /1,000 m Max.) -and-
– Max. Voltage Imbalance (1% Max.)
12C.E.
Motor Parameters – cont’d Abbreviations & Acronyms Motor Currents
– FLA = Motor Full Load Amperes– FLC = Motor Full Load Current = FLA– LRC = LRA = Locked Rotor Current (Amps)– SFA = Service Factor Amps – Locked Rotor Code* – Codes F & G
Common
*May be Much Higher for Smaller Motors and for Energy Efficient Motors
Power Factor (PF) – Real -vs- ImaginaryStarting PF = 30% / 40% TypicallyRunning PF = 85% down to 8.0% from Full Load to No Load, Typically
13C.E.
Motor Parameters – cont’d Motor Current Curve
Motor Current -vs- RPM Curves
Rated Running Current = 100%
14C.E.
Induction MotorLocked Rotor Codes
Maximum Allowed Motor Locked Rotor Codes per NFPA-20:
Code "F" for 15 Hp & up -or-5.0 thru 5.59 KVA/Hp = approx. 540% FLA
Code "G" for for 15 Hp & up5.6 thru 6.3 KVA/Hp = approx. 600% FLA
Code "H" for 5 thru 10 Hp(up to 7.1 KVA/Hp = approx. 685% of FLA)
Code "J" for 5 Hp only(up to 8.0 KVA/Hp = approx. 772% of FLA)
15C.E.
Induction Motor Locked Rotor Codes
Table M-02 -- Motor Locked Rotor Code KVA Data and Allowed Horsepowers
"F" "G" "H" "J" Code Letter
Min. Max. Min. Max. Min. Max. Min. Max.
KVA per Hp 5.00 5.59 5.60 6.29 6.30 7.09 7.10 7.99 LRA/FLA 482% 540% 540% 608% 608% 685% 685% 772% Allowed Hp 15 Hp and up 15 Hp and up 5 thru 10 Hp 5 Hp only
Note: The LRA/FLA ratios shown are approximate for illustration only.
Note: Controllers (15 Hp and higher rated ) are NOT rated, tested, approved, or listed for starting codes above Code "G".
16C.E.
Table M-03 -- Maximum Motor Locked Rotor Currents
Motor Voltage - 60 Hz values Rated
Horsepower
Code
Letters 200 Vac 208 Vac 230 Vac 460 Vac 575 Vac
5 F - J 106 102 92 46 37 7.5 F - H 147 142 128 64 51 10 F - H 186 179 162 81 65 15 F - G 267 257 232 116 93 20 F - G 334 321 290 145 116 25 F - G 421 405 366 183 146 30 F - G 499 480 434 217 174 40 F - G 667 641 580 290 232 50 F - G 833 801 724 362 290 60 F - G 1,001 962 870 435 348 75 F - G 1,249 1,201 1,086 543 434 100 F - G 1,668 1,603 1,450 725 580 125 F - G 2,088 2,008 1,816 908 726 150 F - G 2,496 2,400 2,170 1,085 868 200 F - G 3,335 3,207 2,900 1,450 1,160 250 F - G 4,198 4,036 3,650 1,825 1,460 300 F - G 5,060 4,865 4,400 2,200 1,760 350 F - G 5,865 5,639 5,100 2,550 2,040 400 F - G 6,670 6,413 5,800 2,900 2,320 450 F - G 7,475 7,188 6,500 3,250 2,600 500 F - G 8,338 8,017 7,250 3,625 2,900
Note: The 460 Vac LRA values are from NFPA 20 Table 6-5.1.1. Others are calculated using voltage proportion.
Induction Motor Locked Rotor Currents
17C.E.
Motor Parameters – cont’d Motor Stalled (Locked Rotor) Power Factor = Approx 40%
18C.E.
Motor Parameters – cont’d Motor Theory and Formulae
Purpose – Electrical to Mechanical Energy Conversion
– Motor Starting Region (Rotary Solenoid)– Running Region (Energy Converter)
Motor Torque & Motor Current Draw -vs- Speed Curves A‑T‑L‑Starting
(Basic Motor Characteristics)– Power Factor & Phase Angles– Efficiencies
19C.E.
Motor Starting -vs- Motor Running Regions
20C.E.
Motor Starting -vs- Motor Running Regions
Motoring Region
Starting Region
21C.E.
Motor Parameters – cont’d Motor Torque Curve
Motor Torque and Pump Torque Curves
22C.E.
Motor Parameters – cont’d Motor Torque Curve
Motor Torque and Pump Torque Curves
23C.E.
Motor Parameters – cont’d Motor Current Curve
Motor Current -vs- RPM Curves
Rated Running Current = 100%
24C.E.
Motor Parameters – cont’d Motor Current Curve
Motor Current -vs- RPM Curves
Rated Running Current = 100%
Motoring RegionStarting Region
25C.E.
Motor Theory and Formulae
Motor Starting Region
For a Motor at Stall, Motor Impedance is Constant. So: I = E / Z (Ohm’s Law)
Current is Directly Proportional to Motor Voltage. I.E.:
Motor Current = Voltage / Impedance
Power Factor (P.F.) is Typically 30% to 40% at Stall (and for most of the starting region)
26C.E.
Motor Theory and Formulae
Motor Starting Region – cont’d
In the Starting (Accelerating) Region:
Torque is Proportional to the Square of the Applied Motor Voltage
T = K1 x V2 -or- Since Current is proportional to Voltage (see above):
T = K2 x I2
Thus: Torque is also Proportional to the Square of the Motor Current
27C.E.
Motor Theory and FormulaeMotor Starting Region – cont’d
Example of Starting Torque Proportional to the Square of Applied Motor Voltage.
E.G. 57% Volts = 33% Rated Stall Torque.
28C.E.
Motor Theory and Formulae Motor Running Region
Motor Running Region (Energy Converter):
Mechanical Power is Torque x Speed: Pm = K3 x Tq x RPM
Motor Torque is Whatever the Load Requires
Electrical Power Input is: Pe = Pm + Motor Losses = Pm / Efficiency
But, Electrical Power Input is also given as: Pe = K4 x V x Ireal (Volts x Real Current)
So: Ireal = K5 x Pe / VoltsThus Motor Current is Inversely
Proportional to Motor Voltage with a Running Motor
29C.E.
Motor Running -vs- Motor Starting Regions
Rated Torque (100%) times Rated Speed (E.g. 1750 RPM) yields Motor Rated Horsepower.
30C.E.
IV. Motor Starting General ‑ Overview – Types of
Reduction– Voltage Reduction: Wye–Delta, Soft Start,
and Autotransformer– Current Reduction: Primary Impedance
(Primary Resistor, Primary or Neutral Reactor)
– Motor Impedance (Wound Rotor) Two Specialty Types
– Medium Voltage – Four Common Types: A-T-L, Primary Reactor, Neutral Reactor -and- Autotransformer
– Low Voltage - Wound Rotor (Not U.L. Listed)
31C.E.
Motor Starting - cont’d
Eight (+1) Common Low Voltage Starting Types:
Across‑the‑Line (A‑T‑L or Direct‑On‑Line) Part Winding (Half Winding) Start Primary Resistor Start Primary (or Neutral) Reactor Start Wye‑Delta (Star‑Delta) ‑ Open Transition Wye‑Delta (Star‑Delta) ‑ Closed Transition Soft Start / Soft Stop (SCR Phase
Modulation) Autotransformer VFD Ramp-up (and Ramp-down on some)
32C.E.
Motor Starting – cont’dAcross-the-Line (Direct On Line)
33C.E.
FullVoltageStart ------------Across-the-Line
34C.E.
Motor Starting – cont’dAcross-the-Line (Direct On Line)
35C.E.
Motor Starting – cont’dPart Winding Start
Note: The Motor Must be Wound Specifically for Part Winding Starting.
36C.E.
Part Winding Start
37C.E.
Motor Starting – cont’d
Part Winding Start
38C.E.
Motor Starting – cont’dPrimary Resistor Start
39C.E.
Primary Reactor Start
40C.E.
Motor Starting – cont’dPrimary Resistor Start
Note: 65% Resistor Impedance is
1.24 - 0.40 = 0.84 pu
41C.E.
Motor Starting – cont’dPrimary Reactor Start
42C.E.
Motor Starting – cont’dPrimary (or Neutral) Reactor Start
Note: 65% Reactor Impedance is
1.54 – 1.00 = 0.54 pu
43C.E.
Motor Starting Torque Comparison
Curves B, C & D are at 65% Motor Starting Voltage(Reference Source Credit on Next Slide)
“0”“0”
44C.E.
Motor Torque Comparison – cont’dA=ATL, B=A.T., C=Pri. Res., D=Reactor
Gerhart W. Heumann (G.E.), “MagneticControls of Industrial Motors”, Wiley & Sons.
45C.E.
Motor Starting – cont’dPrimary (or Neutral) Reactor Start
46C.E.
Wye-Delta Open Transition
47C.E.
Motor Starting – cont’dWye-Delta Open Transition
LPM Module = Leading Phase Monitor®
48C.E.
First Half Cycle Offset Waveforms
2.83 x LRA = 6 x 2.83 x FLA = 17.0 x FLA Maximum Theortical This curve shows starting a motor
which still has BACK EMF (voltage) present.
49C.E.
Motor Starting – cont’dWye-Delta Open Transition
50C.E.
Motor Starting – cont’dWye-Delta Open Transition
51C.E.
Motor Starting – cont’dWye-Delta Open Transition
52C.E.
Motor Starting – cont’dWye-Delta Transition Hazard
ClosedLeading
Lagging
53C.E.
Motor Starting – cont’dWye-Delta Closed Transition
54C.E.
Wye-Delta Closed Transition
55C.E.
Motor Starting – cont’dWye-Delta (Open or Closed Xtn.)
56C.E.
Wye-Delta Starting; Truths and Myths
Page 1 of 4
57C.E.
Wye-Delta Starting; Truths and Myths
Page 2 of 4
58C.E.
Wye-Delta Starting; Truths and Myths
Page 3 of 4
59C.E.
Wye-Delta Starting; Truths and Myths
Page 4 of 4
60C.E.
Motor Starting - cont’dSoft (Solid State - SCR) Start
61C.E.
Soft Start (Solid State - SCR)
62C.E.
Motor Starting - cont’dSoft (Solid State - SCR) Start
Note: These curves are for Soft Starters
without Current Limiting set.
63C.E.
Motor Starting - cont’dAutotransformer Start
64C.E.
Autotransformer Start
65C.E.
Motor Starting - cont’dAutotransformer Start
Motor Starting Characteristics
Parameter Chart
Fire Pump Starting Type Characteristics - for - Electric Fire Pump Motors and Controllers
Starting Characteristics (at Stall) -- Typical Values -for- Fully Load Pump (1) Starting Starting Starting Accelerate Motor Motor Amps Amps Starting Power Starting Full Load Type Contactors Closed & KVA & KVA Power % F.L. Torque to Starting Type Note Note (3) Transition % LRA % FLA Factor Note (4) % ATL Full Speed Notes Across-the-Line Any 1 N/A 100% 600% 40% 240% 100% Yes (a)
Part Winding Special (2) 2 Yes 65 390 40 156 48 Usually (b) Primary Resistor Any 2 Yes 65 390 80 314 42 Yes (c)
Primary Reactor Any 2 Yes 65 390 28 111 42 Yes (c) Neutral Reactor 6/12 Lead 2 Yes 65 390 28 111 42 Yes (c)
Wye-Delta Open 6/12 Lead 3 No 33/100 200/600 40 80/240 33 No (d) Wye-Delta Closed 6/12 Lead 4 Yes 33/100 200/600 40 80/240 33 No (d)(e)
Soft Start/Stop Any 1/2 Yes 40/67 240/400 Varies Ramps 16/44 Yes (f) Autotransformer Any 3 Yes 46 276 40 110 42 Yes (c)(g)
67C.E.
Motor Starting Characteristics
Parameter Notes to Chart
Motor Starting Characteristics Chart Notes (1) Refer to Factory details. (2) Part Winding Motors must be wound specifically for this service. Some motors may not
accelerate to full speed in the starting mode. See Note (b). (3) Units with two or more contactors have two basic steps (Accelerate & Run) with steps three
and four being for transitions. (4) Starting KW Power as a percent of motor full load power requirement. (a) Also called "A-T-L" or Direct-On-Line. Motor Power Factor taken as 40%. Other values
shown are due to the effects of the controller. (b) Part Winding Parameters vary with the motor. Starting Amps & KVA vary from around
60% to 70%, Starting Torque from around 45% to 50%. The motor can start a fully loaded pump if it has no large torque dip or cusp. See the text discussion on Part Winding Starting for details.
(c) Figures are for tap set at 65% which yields a motor voltage of 65% of line (mains) voltage. (d) The Dual Figures are for Starting and Transition. The transition values are to finish
accelerating a fully loaded pump. Examples include deluge or open systems, re-starting a fully loaded pump after a power failure or interruption, and failure of another pump feeding the same system.
(e) Ignores the momentary transition resistor loads. (f) Varies with pump load and particular Soft Starter used. Values shown are initial and
maximum for a typical fully loaded pump. MCS uses the second (Start) contactor for isolation. Others use only the Bypass contactor.
(g) The 46% Starting Amps & KVA figures include the Autotransformer exciting current.
68C.E.
V. Motor Running TypesConstant Speed Running Full Voltage Running
- Synchronous Speeds (3,600 RPM & etc.)- Slip Frequencies - Running (Rated)
Speeds Motor Lead Wire Running Currents
- Three Lead = Full Motor Current- Six Lead Parallel Run (Part Winding
Start)= 50% of FLC per set
- Six Lead (Wye-Delta Start)= 58% (57.7%) of FLC per set
69C.E.
Motor Running - cont’d
Variable Speed Running Wound Rotor Control
- Changes Motor Secondary Impedance -and-
- Motor Torque Curve Variable Frequency - Variable Speed
Control (VFDs)- Changes Motor Torque and Current
Curves
- Changes Motor Synchronous Speed –and-
- Changes Motor Running (Loaded) Speed
70C.E.
Wound Rotor Speed-Torque Curves
(Reference Source Credit on Next Slide)
71C.E.
Wound Rotor Speed-Torque Curves
- Flipped and Rotated -
Gerhart W. Heumann (G.E.), “Magnetic
Controls of Industrial Motors”, Wiley & Sons.
72C.E.
VFD = Motor Running Only (No Motor Starting Region)
Starting Region
(Reference Only)
73C.E.
Variable Speed ControllersPower Circuit Schematic
. .* Was Optional
74C.E.
Variable Speed Control
75C.E.
VFD – Principles of Operation
3 Phase
Line Freq.
AC to DC
Smoothing(Ripple Reduction)
DC / AC
(at "X" KHz)
76C.E.
VI.Motor Wiring – Motor Lead Configurations (Fourteen)
Three Lead – Three Coil
(Single Voltage) (T1‑T3) Six Lead – Three Coil
– Wye Running (T1‑T3 & T4‑T6)– Delta Running (T1‑T3 & T4‑T6)
Parallel Run (Six Lead - Six Coil)– T1‑T3 and T7‑T8 - or -– Both Sets Labeled T1‑T3
77C.E.
Motor Lead Configurations3 Lead – 3 Coil - Wye Running
78C.E.
Motor Lead Configurations3 Lead – 3 Coil - Delta Running
79C.E.
Motor Lead Configurations6 Lead - 3 Coil - Wye Running
80C.E.
Motor Lead Configurations6 Lead – 3 Coil - Delta Running
81C.E.
6 Lead – 6 Coil - Wye RunningParallel Running
82C.E.
6 Lead – 6 Coil - Delta Running Parallel Running
83C.E.
Motor Wiring – cont’d
Nine Lead (Dual Voltage) (T1‑T9)– Wye Wound– Delta Wound– Suitable for Part Winding Start ?
Twelve Lead (T1‑T12)– Dual Voltage– Single Voltage (Parallel Run)
84C.E.
9 Lead - 6 Coil - Wye RunningSeries Running
85C.E.
9 Lead - 6 Coil - Wye RunningParallel Running
86C.E.
9 Lead - 6 Coil - Delta RunningSeries Running
87C.E.
9 Lead - 6 Coil - Delta RunningParallel Running
88C.E.
12 Lead - 6 Coil - Wye RunningSeries Running
89C.E.
12 Lead - 6 Coil - Wye RunningParallel Running
90C.E.
12 Lead - 6 Coil - Delta RunningSeries Running
91C.E.
12 Lead - 6 Coil - Delta RunningParallel Running
92C.E.
Typical 12 Lead Motor Wiring Diagram
Courtesy of Marathon Electric
93C.E.
Starting Methods -vs- Motor
Types
Table M-04 - Motor and Starting Types
Starting Type Motor Type Starting Type Motor Type
Full voltage Standard/Any Primary Reactor Standard/Any
Part Winding Part Winding Primary Resistor Standard/Any
Wye Delta - Closed Delta Run Autotransformer Standard/Any
Wye Delta - Open Delta Run Soft Start (SCR) Standard/Any
Neutral Reactor Wye Running Wound Rotor Wound rotor
94C.E.
Motor Types -vs- Starting Types
Motor Description (a) Starting Method(b)
Run Type Number of Leads Part Winding
Wye (Star) Delta(c)
Neutral Reactor
"Other 5" Figure
Wye Run Three Lead No No No Yes 7-4
Delta Run Three Lead No No No Yes 7-5
Wye Run Six Lead, Single Coil No No Yes Yes 7-6
Delta Run Six Lead, Single Coil No Yes No Yes 7-7
Wye Run Six Lead Parallel Some(d) No No Yes 7-8
Delta Run Six Lead Parallel Some(d) No No Yes 7-9
Wye Run Nine Lead Series No No Yes Yes 7-10
Wye Run Nine Lead Parallel Some(d) No No Yes 7-11
Delta Run Nine Lead Series No No No Yes 7-12
Delta Run Nine Lead Parallel No(e) No No Yes 7-13
Wye Run Twelve Lead Series No No Yes Yes 7-14
Wye Run Twelve Lead Parallel Some(d) No Yes Yes 7-15
Delta Run Twelve Lead Series No Yes No Yes 7-16
Delta Run Twelve Lead Parallel Some(d) Yes No Yes 7-17
Notes: (a) The Motor "Type" (Wye or Delta) is the Running configuration, regardless of how the motor is started. Wound Rotor Motors are not covered in this chart. (b) "Other 5" are: Full voltage (A-T-L), Primary Resistor, Primary Reactor, Soft Start and Autotransformer. (c) Either Open or Closed Transition Wye-Delta (Star-Delta). (d) "Some" = May be used only of the motor is labeled as suitable for Part Winding Starting. (e) The 9 lead "Double Delta" method has unequal currents and is not suitable for standard Part Winding controllers.
Table M-06 -- Motor SuitabilityMotor Types -vs- Starting Types
95C.E.
VII. Induction Motors --Installation Considerations
Physical– Location ‑ Ideally Within Site of Controller– Motor Protection: Fire, Security, Other
Hazards Access – All Sides & Conduit Access Electrical N.E.C. (NFPA 70) ‑ §430 (& §
695)– Conduit & Hubs– Environmental– Conductor Sizing – Incoming & Motor Circuit– Voltage Drops: Start & Run– Cable Impedances and Run Lengths
(See NEMA ICS-14)
96C.E.
Motor Installation – cont’d
Start-up (Commissioning)
Current Measurements Voltage Measurements Estimating Motor Load
- FLA -vs- Voltage
- SFA (115%) - Max. Allowed Under Any Conditions (Temperature, Altitude, Voltage Imbalance) on ANY Phase
97C.E.
Motor Installation – cont’d
Environmental Open Drip Proof (ODP) Totally Enclosed Fan Cooled (TEFC) Outdoor Hazardous Locations, Explosion
Proof:– Motor, Controller, Wiring
Other– Salt Air– Wind Blown Sand or Dust– Temperatures– Altitude