i.l. 41-766.1n sc, sc-1, sv and sv-1 relay - abb ltd · vides the high ratio of dropout to pickup...

I.L. 41-766.1N SC, SC-1, SV and SV-1 Relay

frame. The position of this shunt determines the pick-up setting of the relay. The lower end of the shunt isbeveled and knurled, so that it can be grasped by thefingers and turned to change the setting. A calibratedscale plate is mounted adjacent to the shunt. Agroove just above the knurl in the lower end of theshunt serves as an index mark, and the relay pick-upsetting is indicated by the calibration scale markingwhich is adjacent to the groove.

The construction of the plunger, core and flux shunt(which differ in details in the various types of theserelays) causes the plunger to float in its energizedposition, without being held against a stop, evenwhen energized much above the pickup value. Con-sequently, there is negligible noise and chatter, evenon heavy overloads and in 25 hertz applications.

The core, shunt and plunger construction also pro-vides the high ratio of dropout to pickup in the SC andSV relays. This ratio is above 90% for any pickup set-ting. In the latch type relays it is necessary for theplunger to rise with sufficient force to operate thelatch positively and to deflect the stationary contactssufficiently to prevent their opening, when the relay isde-energized, due to play in the latch. It is necessaryto have a lower ratio of dropout to pickup in order toobtain this characteristic, and this lower ratio may bedesirable in some applications where the latch is notrequired. The plunger floats in its operated positionjust as in the SC and SV relays. The dropout ratiovaries somewhat for different shunt positions, but isconstant for any one setting.

The shunt is held in any desired position by pressurefrom a curved arm made of sheet spring steel, whichis fastened to the bottom of the coil frame at the rearof the shunt. This spring arm is shaped to extendaround the shunt to the front of the relay, and in itsnormal position it exerts sufficient pressure againstthe shunt to prevent any creeping of the shunt orundesired change of setting. The front end of thespring arm has a bent-over tab on which thumb-pres-sure may be applied to move the arm out of contactwith the shunt while the position of the latter is beingchanged.

The stationary contacts are assembled on slottedbrackets. These are held in position on the base byfilister-head screws which are threaded into the ter-

2

minal inserts. Lockwashers are assembled insidethe molded terminal bushings between the insertsand the base, as a safeguard against loosening ofthe screws. By rotating the bracket on its mountingscrew and moving it along its slot, the contactassembly can be made either normally open or nor-mally closed. The moving contacts are mounted ona Micarta insulation plate which is secured to thethreaded end of the plunger shaft by a nut. Thefront edge of this insulation plate operates the indi-cator. The rear portion of the plate is slotted and apost screwed to the frame passes through this slotto prevent the plate from rotating. The moving con-tacts are double-faced so that they can be “make”or “break” and are connected to the base terminalsby flexible leads. All contacts are pure silver. Thecontacts will carry 5 amperes continuously, and willinterrupt 5 amperes at 115 volts ac, or 1 ampere at125 volts dc.

The mechanical operation indicators used on theserelays are shockproof, and can be used to indicate onthe up stroke or down stroke of the plunger. The indi-cator is reset by pulling out the knurled stud whichprojects through the cover nut. The indicator shouldbe reset after each relay operation, otherwise theremay be a one or two percent decrease in the operat-ing value of the relay. The operation indicator isassembled at the factory to indicate on the up strokeof the plunger but by removing the two mountingscrews which fasten the indicator to the main frame,turning the indicator bracket around and at the sametime swinging the indicator flag 180° about its shaft,the indicator can be set to indicate on the downstroke of the plunger. The rivet weight must beremoved from the indicator flag and the latch screenturned around to complete the assembly.

In certain applications, an extremely wide range ofcurrent adjustment is desirable, and certain styles ofSC and SC-1 relays have been provided with tappedcoils to meet this requirement. The coil taps arebrought out to a tap block mounted on the lower endof the relay frame or on the relay sub-base, depend-ing on the type of case used. The connector plate onthe tap block is marked with the minimum pickupvalue of each tap and the shunt is adjusted in theusual manner to obtain any pickup setting betweentaps. The scale plate is not calibrated for the relays

SC, SC-1, SV and SV-1 Relay I.L. 41-766.1N

with tapped coils, as there is not sufficient space formarking a scale for each tap. However, the scaleplate is supplied in order that a customer may markon it the individual relay setting or settings if desired.

3.0 INSTALLATION

The relays should be mounted on switchboard pan-els or their equivalent in a location free from dirt,moisture, excessive vibration, and heat. Mount therelay vertically by means of the four mounting holeson the flange for semi-flush or by means of the rearmounting stud or studs for projection mounting.Either a mounting stud or the mounting screws maybe utilized for grounding the relay. The electrical con-nections may be made directly to the terminals bymeans of screws for steel panel mounting or to theterminal studs furnished with the relay for thick panelmounting. The terminal studs may be easily removedor inserted by locking two nuts on the stud and thenturning the proper nut with a wrench.

For detailed FT case information refer to I.L. 41-076.

4.0 ADJUSTMENTS AND MAINTE-NANCE

The proper adjustments to insure correct operation ofthis relay have been made at the factory and shouldnot be disturbed after receipt by the customer. If theadjustments have been changed, the relay takenapart for repairs, or if it is desired to check the adjust-ments at regular maintenance periods, the instruc-tions below should be followed.

All contacts should be cleaned periodically. A contactburnisher Style 182A836H01 is recommended forthis purpose. The use of abrasive material for clean-ing contacts is not recommended, because of thedanger of embedding small particles in the face ofthe soft silver and thus impairing the contact.

Several factors may affect the dropout ratio of therelay. Whatever affects the ratio does so becauseeither the dropout or pickup or both are affected.Obviously, incorrect assembly or interchange ofparts, such as the use of the SC plunger with the SVcore tube, will alter the electrical characteristics.However, the factor most likely to be encountered inservice is friction. This may be due to dirt or foreignmaterial between the plunger shaft and its bearings,

to excessive pressure of the indicator screen on theindicator, or to leads so mis-shaped that they tend torotate or tilt the moving contact insulation plate withappreciable force.

In order to remove the plunger and shaft assembly, itis necessary to remove the setscrew and nut at thetop of the shaft. The spool-shaped bushing assem-bled on the upper end of the plunger shaft has a por-tion of its center section machined off so that theshaft is exposed at this point and can be preventedfrom turning by gripping shaft and bushing with a pairof long-nose pliers while removing the set screw andnut. Then by pressing down with the fingers on theupper end of the shaft, the lower split sleeve whichretains the lower bearing will be forced out of thethreaded tube, the bearing will drop out freely, andthe upper split sleeve will be forced out far enough topermit grasping it for removal. The shaft and plungerassembly then can be removed.

The shaft and plunger assembly should be handledcarefully to avoid bending the shaft or damaging thebearing surfaces. The shaft should never be grippedon it upper bearing surface, below the spool-shapedbushing, when loosening the nut and setscrew, asthis would almost certainly damage the bearing sur-face. The shaft bearing surfaces should not becleaned or polished with any abrasive material, asthe abrasive particles might become imbedded in theshaft and cause difficulty later. The plunger shaft andbearings may be cleaned by wiping them carefullywith a clean, lint-less cloth. Use no lubricant on theplunger shaft or bearings when re-assembling therelay, since this will eventually become gummy andprevent proper operation. It is recommended that theshaft be cleaned at intervals of approximately twoyears. When replacing the lower bearing and the splitsleeves, the shorter sleeve (assembled below thebearing) should be pushed in until it is flush with theend of the threaded tube.

The mounting holes in the operation indicator screenare slotted so that its position can be adjusted. Forrelays in which the moving contacts are not latchedin the operated position, the screen should be solocated that the indicator positively enters the screenopening when the contacts barely touch. For latch-type relays, the screen should be so located thatgood contact is still obtained when the relay is de-

3


energized. The pressure of the screen against theindicator may be adjusted by bending the screenbetween its lower end and the large elongatedhole.This pressure should be such that the indicatorwill be held at any further position to which it is movedafter entering the screen opening. However, the mini-mum amount of pressure necessary to obtain thisadjustment should not be exceeded appreciably, sincethe pick-up value, and consequently the ratio, will beaffected. The purpose of this pressure is to eliminateindicator rattle which might otherwise occur under cer-tain energized conditions.

The moving contact leads pass through insulationsleeves assembled on the shanks of the terminal clipswhich are attached to the base terminals. Thesesleeves are notched at their upper ends, and thenotches are toward the center of the relay. The leadsare bent at approximately a right angle where they passout through the notches, which aids in preventing themfrom coming into contact with the stationary contactbrackets. Figure 1, (page 8) shows properly coiled andassembled moving contact leads.

Although the moving contact leads are very flexible, ifthe leads have been pulled out of their original shapeby handling they may exert sufficient side pressure onthe shaft bearing or twisting force against the guidepost to cause appreciable friction and wear. If this con-dition continues for a long period of time, the resultingwear may affect the relay calibration or the dropout rationoticeably. In extreme cases the wear may progress toa degree which may occasionally cause failure of theplunger to drop down when the relay is de-energized.

Correct shaping of the leads is not difficult, and theymay be checked readily by removing the guide postand the nut at the top of the shaft. The plungershould be held in the raised position, either by ener-gizing the relay or by pressing lightly against the col-lar under the insulation plate after raising the plungermanually. With the plunger raised, the insulationplate should be oscillated slightly in a horizontalplane by twisting it horizontally and releasing it. If inseveral trials the plate comes to rest with the centerline of the contacts approximately parallel to thebase and with its mounting hole fairly well centeredwith the end of the shaft, if the plate does not tipappreciably, and if the leads have a safe clearanceto the stationary contact brackets, the leads are

properly shaped.

If this check shows that re-shaping is necessary, itmay be possible to obtain sufficient correction bybending the leads sharply where they emerge fromthe insulation sleeves. One or two pairs of tweezersare tools for re-shaping the leads. If it is necessaryto re-coil the leads, they should be wound around arod having a diameter of approximately 5/32”. Thecoils then should be stretched out just enough toavoid side pull or twisting force on the plungerassembly.

In all relays except the SV-1 relay for ac, if the sta-tionary contacts are assembled so that they closewhen the relay is energized, they should be locatedso that they barely touch the moving contacts whenthe latter are 5/32” above the de-energized position.The moving contacts can be held in this positionwhile the adjustment is being made by inserting a 5/32”spacer between the shaft collar and the top of thecore. This dimension should be 3/16” on the SV-1relay for ac. Both contacts should touch at the sametime when the plunger is raised. When the plunger ismoved upward against its stop, there should be aslight deflection of the stationary contact stopsprings, but this should not exceed 1/32”. When thestationary contacts are reversed so that they areclosed when the relay is de-energized, they shouldbe located so that they just touch the moving con-tacts when the latter are 1/32” above the de-ener-gized position. On some relays it may be found thatwhen the contacts are used in this position the relaymay operate at values a few percent below the scalemarkings. The adjustments specified for the station-ary contacts are important. Failure to observe themmay cause improper relay operation, either directlyor after a period of service. Contact position shouldnot be used as a means of altering the ratio of drop-out to pickup.

5.0 RENEWAL PARTS

Repair work can be done most satisfactorily at thefactory. However, interchangeable parts can be fur-nished to the customers who are equipped for doingrepair work. When ordering parts, always give thecomplete nameplate data.

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5

THIS SPACE RESERVED FOR NOTES


6

CHARACTERISTICS OF TYPES SC AND SC-1 RELAYS

Type FrequencyRange of

AdjustmentAmps.

Max. Amps.Continuous

Watts at5 Amps.

60 Cycles

V.A. at5 Amps.

60 Cycles

DropoutRatio-AC

DropoutRatio-DC

SCSCSCSCSCSCSCSC

DC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 Hz

.5-21-42-8

4-1610-4020-80

40-1604-100

1.536

12254040

10-15-20

99286.91.5.24.07.03

1.7-0.6-0.18

22565195.7

.16

.055-1-0.2

85-98%85-98%85-98%85-98%85-98%85-98%85-98%85-98%

65-80%65-80%65-80%65-80%65-80%65-80%65-80%65-80%

SC-1SC-1SC-1SC-1SC-1SC-1SC-1SC-1

DC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 HzDC, 25 to 60 Hz

.5-21-42-8

4-1610-4020-80

40-1604-100*

1.536

12254040

10-15-20

100246

1.5.25.07.03

1.7-0.6-0.18

21060165

.65

.16

.055-1-0.2

35-60%35-60%35-60%35-60%35-60%35-60%35-60%35-60%

25-40%25-40%25-40%25-40%25-40%25-40%25-40%25-40%

* Coil has taps on which minimum pickups are 10 and 30 amperes.


CHARACTERISTICS OF SV AND SV-1 RELAYS

TypeFrequency

(Hertz)

Range ofAdjustment

Volts

Max. VoltsContinuous

Watts at115 V. AC

(125 V. For DC)

V.A. at115 V.

Dropout Ratio

SVSVSVSVSVSVSVSV

606060605025DCDC

7-1670-160

140-320280-640

70-16070-16050-150

100-300

16160320640180200150300

—3.4——2.81.54.8—

—7.3——6.12.5——

85-98%85-98%85-98%85-98%85-98%85-98%65-80%65-80%

SV-1SV-1SV-1SV-1SV-1SV-1SV-1SV-1

606060605025DCDC

7-1670-160

140-320280-640

70-16070-16050-150

100-300

16160320640180200150300

—4.1——3.51.44.8—

—8.5——7.13.2——

40-80%40-80%40-80%40-80%40-80%40-80%25-40%25-40%

7

NOTES: Standard current relays are calibrated on 60 hertz. This calibration is approximately correct for 25 hertz and dcapplications, but there will be discrepancies of 10% to 15% at some points on the scale.

Values of watts and volt-amperes in the tables are average for various plunger and shunt position.

For the SC relay, volt-amperes for pickup at minimum setting are approximately 3.4 and 1.4 for 60 and 25 hertz.Watts at minimum setting are approximately 1.0,.65 and.57 for 60 hertz, 25 hertz and DC respectively. Multiplyvalues by 16 for approximate burdens at maximum setting.

For the SC-1 relay, volt-amperes for pickup at minimum setting are approximately 3.5 and 1.3 for 60 and 25hertz. Watts at minimum settings are 1.3, .7 a n d.57 for 60 hertz, 25 hertz and dc respectively. Multiply values by16 for approximate burdens at maximum setting.

* The V.A. burdens of the SC and SC-1 relays at 3, 10 and 20 times minimum pickup current are approximately 31,240 and 770 V.A. respectively.

Dropout ratio varies somewhat with pickup adjustment but will be approximately constant for any given pickupsetting. Limits in tables include variables such as friction and other individual relay variations.

Maximum continuous volts given for the SV and SV-1 relays for ac are for the relay set for minimum pickup. Withthe relay set for maximum pickup the continuous voltage can be increased 10 to 20%.


Moving Contact Leads

Sub 4182A854

Figure 1: View of Type SV Relay showing correct shap-ing of moving contact leads

8

Sub 4182A855

Figure 2: Internal Schematic of the Single Unit Type SCor SC-1 Relay in the Type FT-21 Case

Sub 1182A856

Figure 3: Internal Schematic of the Double Unit Type SC or SC-1 Relay in the Type FT-21 Case

Figure 4: Internal Schematic of the Single Unit Type SV or SV-1 Relay in the Type FT-21 Case


Sub 1182A857

Contacts - EitherMake or BreakAs Required

Left-hand Unit(Front View)

Right-hand Unit(Front View)

Red Handle

Test Switch

Terminal

TYPE OF UNIT

LOCATION OF EACH UNIT

RIGHT HAND LEFT HAND

SAME TYPE(SV, SV1)

SAME TYPEBUT DC & AC

LOWER RATINGUNIT

HIGHER RATINGUNIT

DC AC

ARRANGEMENT OF UNITS

Sub 5183A193

Note: When SC or SC-1 CoilRatings are Different - TheLower Rated Current ElementTo Be Assembled in BottomPosition of Relay.

Contacts - EitherMake or BreakAs Required

Bottom Unit

Top RH Unit(Front View)

Top LH Unit(Front View)

Chassis OperatedShorting Switch

Test SwitchCurrent Test Jack

Terminal

Note: Coils tapped for1 to 25 Ratio Range(when used)

Figure 5: Internal Wiring of the Relays in the SmallGlass Case

Figure 6: Internal Schematic of the Single Unit Type SCor SC-1 Relay in the Type FT-21 Case

Sub 2183A192

CONTACTS - EITHERMAKE OR BREAK ASREQUIRED

BOTTOM UNIT

TOP LEFT-HAND UNIT(FRONT VIEW)

TOP RIGHT-HAND UNIT(FRONT VIEW)

TERMINAL

TEST SWITCH

* Sub 7

871766

Figure 7: Internal Schematic of the Double Unit Type SCor SC-1 Relay in the Type FT-21 Case

* Denotes Change

Figure 8: Internal Wiring of the Relays in the Small Glass Case

9


Sub 5184A942

Figure 9: Internal Schematic for Relays in Front Connected Case

10


Sub 1143285

Figure 10: Typical Time Curves for the Types SC and SV Relays (Using Flux Shunt for Pickup Adjustment)

11


12

Sub

147

1008

Fig

ure

11:

Typ

ical

SC

& S

C-1

Cur

rent

Rel

ays

dc o

r 25

to 6

0 H

ertz


Sub

147

1013

Fig

ure

12:

Pic

kup

on V

aria

ble

Fre

quen

cy fo

r S

C &

SC

-1 C

urre

nt R

elay

s

13


14

Sub

147

1009

Fig

ure

13:

Typ

ical

Typ

e S

V V

olta

ge R

elay

(12

0 V

olts

60

Her

tz R

ange

70

to 1

50 V

olts

)


Sub

147

1020

Fig

ure

14:

Pic

kup

on V

aria

ble

Fre

quen

cy fo

r S

V R

elay

120

vol

ts 6

0 H

ertz

(S

et a

t 70

volts

)

15


16

Sub

677

D41

8

Fig

ure

15:

Out

line

and

Dril

ling

Pla

n fo

r S

ingl

e U

nit R

elay

s in

sm

all g

lass

pro

ject

ion

case


Sub

5

188A

098

Fig

ure

16:

Out

line

and

Dril

ling

Pla

n fo

r R

elay

s in

Fro

nt C

onne

cted

Cas

e

17


18

*S

ub 1

757

D79

01

Fig

ure

17:

Out

line

and

Dril

ling

Pla

n fo

r S

ingl

e an

d D

oubl

e U

nit R

elay

s in

the

Typ

e F

T-2

1 C

ase


Sub

17

57D

7903

Fig

ure

18:

Out

line

and

Dril

ling

Pla

n fo

r T

hree

Uni

t Rel

ays

in T

ype

FT

-32

Cas

e

19

ABB Inc.4300 Coral Ridge DriveCoral Springs, Florida 33065Telephone: +1 954-752-6700Fax: +1 954-345-5329www.abb.com/substation automation

IL 4

1-76

6.1

- Rev

isio

n N

ABB

i.l. 41-766.1n sc, sc-1, sv and sv-1 relay - abb ltd · vides the high ratio of dropout to pickup...

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