GEI-86134CSupplement to GEK-7310MAINTENANCE MANUAL

(SUPPLEMENT)

LOW-VOLTAGE POWER CIRCUIT BREAKERSTYPE AKR

*. i

This manual when used in conjunction with Publication GEK-7310 (Main-tenance Manual for AKR-3/3A-50 and AKRU-3A-50 breakers) provides main-tenance instructions on the AKR breaker models and trip devices listed inTablet .• • :

TABLE 1

Breaker Type & Mounting Trip Device TypeFrameSize(Amp) Stationary Drawout ECS SST

AKR-4-30, 3OH AICR-4A-30, 3OH XV

AKR-5-30, 30H AKR-5A-30, 3OH X« *800

AKRU-4A-30* X

AKRU-5A-30* X

AKR-4-50, 5OH AKR-4A-50, 50H X

AKR-5-50, 5OH AKR-5A-50, 5OH X1600

AKRU-4A-50* X

AKRU-5A-50* X

AKRT-4-50 AKRT-4A-50 X2000

: iCAKRT-5-50 AKRT-5A-50

* - Integrally fused typesf -

E L E C T R I CyjmuG E N E R A L m

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CONTENTS

:•.

Introduction 3

Constructional Differences 3

Breaker Ratings 4

Drawout Breaker Interchangeability 5

Breaker MaintenancePrecautions , .Manual Handle Adjustment . <

Contact MaintenanceContact Adjustment:

AKR-30, -30II , AKRU-30AKR-50, -50H, AKRU-50AKRT-50

Contact Replacement:AKR-30, -30H, AKRU-30AKR-50, -50H, AKRU-50, AKRT-50 . . . . 10

6666

788

10

Fused Breakers AKRU-30, -50Fuse Sizes and Mounting . .Special 2500A FuseOpen Fuse Lockout Device .

10101212v

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14r- Type SST Overcurrent Trip Device . . . .Components

* • Trip CharacteristicsTroubleshooting . .SST Test Set TAK-TS1False Tripping (Ground Fault)Replacement of Current Sensors , . . .Flux Shift Trip DeviceCabling DiagramsGround Fault Defeat Cable . .

1416ft:I V: . . . 17. . . 18

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19. . . 19. . . 20{-i

22! ‘ . . . 23

. . . 24Type ECS Overcurrent Trip Device . . . .ComponentsTrip CharacteristicsCabling Diagram

24;

2526

. . . 27ECS & SST Time-Current Curves . . . .

These instructions do not purport to cover all details or variations in equipment nor to provide for every possible contingency to be met in connectionwith installation, operation or ma/nfenance, Should further information be desired or should particular problems arise which are not covered sufficientlyfor the purchaser’s purposes, fbe matter should be referred to the General Electric Company,=

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Power Circuit Breakers, GEI-86134

m MAINTENANCE MANUAL SUPPLEMENT

LOW-VOLTAGE POWER CIRCUIT BREAKERSTYPES AKR/AKRU-30/50, AKRT-50 PER TABLE 1

INTRODUCTIONAKR-30H, Same as the AKR-30 except for modifi-cations fn the following areas:The data in this supplement pertains to the new

80GA AKR-30 and the 2000A AKRT-50 framebreakers not covered by the existing AKR/AKRU-50maintenance manual (publication GEK-7310). In- a. Arc quenchers,

formation on the new ECS and SST solid-state tripdevices also is included. b. Closing springs,

c, Extra insulation on shaft flyweights.The new breaker models are derivatives of the

1600A frame AKR-50 design. Apart from the spe-cific constructional differences identified below, thebasic AKR-50framework, mechanism and accessorydevices are substantially common to all versions.Except for the 800A frame primary stud details,the external H x W x D dimensions are identical.Accordingly, a majority of the AKR-50 informationnow in publication GEK-7310 applies equally to thenew types, Therefore, to avoid needless repetition,the scope of this Supplement is confined principallyto that descriptive and instructional material uniqueto the new models, Unless noted to the contrary,

or otherwise discussed herein, the user shouldcontinue to employ GEKr7310 as the general, op-erational information source ,

d, Mounts one additional stationary main contactfor a total of four; otherwise the contact struc-ture is same as AKR-30, See Fig, 6,

NOTE: To visibly distinguish it from theAKR-30, the closing springs and arcquencher covers of the 3OH are coloredred,

Complementing the above "new" material, thissupplement includes additional information to ex-pand and update existing GEK-7310 subject-matterwhere appropriate. Examples are revision of theoperating handle adjustment procedure and reduc-tion of the AKRU-50 minimum fuse size from 800Ato 45OA ,

CONSTRUCTIONAL DIFFERENCES

The features which distinguish the new AKR/AKRT breakersfrom the parent AKR-50 frame sizeare listed below. For a detailed parts comparison,refer to ''Renewal Parts Bulletin" GEF-4527,

AKR-30.a, An entirely new contact structure, Each pole

employs three stationary mains, two stationaryaiming and one movable contact arm. See Fig. 5,

b, Primary studs carry four disconnect fingers perpole. See Fig, 1,

c, Two additional opening springs, one at each endof the main shaft. See Fig. 4, Fig, 1, Rear view of AKR-30 breaker

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GEI-86134, Power Circuit Breakers

BREAKER RATINGSAKR-5OH. AnAKR-50 with extended short circuitratings attained by special arc quenchers, closingsprings and added insulation. Quencher tops andclosing springs carry the same red color used onthe AKR-3OH.

AKR breakers are available in three frame sizes— BOO, 1600 and 2000 amperes. These values re-present the maximum continuous current capabilityof the respective frames. However, each breakercarries a specific rating which is determined by thecurrent sensor ampere rating (or tap setting) of thetrip device with which it is equipped.

AKRT-50. A 2000A extension of the 1600A frameAKR-50. Modifications are:

a. New and larger upper stud assembly, movablecontact arms and pivot block.

b. Stationary main contacts increased from 6 to 8;otherwise the stationary contacts are identicalto the AKR-50. See Figs. 8 and 9.

EXAMPLE: An AKR-5A-30 breaker with SSTsensor tap set on 100A is rated 100A.

Short circuit ratings vary with the applied systemvoltage. On 240 V systems they are also dependentupon whether the overcurrent trip device containsan instantaneous trip element. See Table 2.

TABLE 2BREAKER RATINGS

* •/.

3 ( j) Short Circuit Rating(kA RMS Sym )Rated

MaximumVoltage

FrameSize(Amperes)

BreakerType With

InstantaneousTrip

WithoutInstantaneous

TripX : r, ‘ (60Hz ac)\ 635 30 30\ AKR-30 508 30 30

' 254 42 30800

635 42 42508 42AKR-3OH 42254 50 42

635 4242AKR-50 508 50 50

254 65 501600

635 50 50y: AKR-5OH 508 65 65i?•

254 65 65

635 42 422000 AKRT-50 508 50 50

254 65 50

800 AKRU-30 200 200600.i

1600 AKRU -50 600 200 200Vi,

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S'uPower Circuit Breakers, GEI-86134 :*KiV •

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a. An AKR-30H can be inserted into an AKR-30compartment.DRAWOUT BREAKER

INTERCHANGEABILITYft--:1-llb. An AKR-50H can be inserted into an AKR-50

compartment. hIn general, drawout breakers of the same typeand rating are interchangeable in their equipmentcompartments; drawout breakers of different framesizes are not interchangeable. To prevent insertingthe wrong type breaker into a drawout compartment,suitable "rejection hardware" is affixed to eachbreaker and its compartment. Figure 4 shows atypical rejection bracket which aligns with a re-jection pin in the drawout rail (Fig. 3). When thewrong type breaker is inserted into a compartmentthe bracket and pin do not mate, preventing thebreaker from seating itself into the drawout rails.

The rejection hardware prevents the converse ofa. and b.

Figure 2 shows the rejection pin and bracketcombinations employed , As determined by its in-tended breaker type, each drawoutcompartment hasits rejection pin (or pins) installed in one of threepositions (A, B or C front-to-rear) along the sliderail(s) . Referring to Views 2 and 5, note that onlythe AKR-30H and 50H types employ twopins, one ineach slide rail. The other breaker types use asingle pin in the right side rail. AKRU-30 and 50fused breakers use a single bracket, whereas allnonfused breakers carry two brackets. Use Fig. 2as a guide for determining the proper breakertype(s) that will be accepted by any given compart-ment.

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*I&iThere is one exception to the above. Breakers

of the same frame size having different short cir-cuit ratings may be interchanged in one directiononly:

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MOUNTED ONBREAKER

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COMPARTMENT IAKR - 30H

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AKRU - 30 AKRU- 50PIN

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r:Fig, 2, Non-interchangeability (rejection)hardware arrangements in drawoutcompartments for breaker TypesAKR-30/30H/50/5OH, AKRT-50 andAKRU-30/50

Fig . 3. Slide rail rejection pin locations •

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GEf-86134, Power Circuit Breakers

Fig. 4. AKR-&4-30 breaker

1. Opening spring2. Rejection bracket

If the link is too long, the handle stroke cannotextend the closing spring enough for it to go overcenter. In this event, use the maintenance handleto complete the spring charging , The breaker canthen be closed and opened preparatory to furthershortening of the link ,

BREAKER MAINTENANCE

SAFETY PRECAUTIONS

BEFORE INSPECTING OR BEGINNINGANY MAINTENANCE WORK ON THEBREAKER, IT MUST BE DISCONNECTEDFROM ALL VOLTAGE SOURCES, BOTHPOWER AND CONTROL, AND BE INTHE "OPEN" POSITION,

If the link is too short, one-stroke charging isnot possible. However, more than one stroke willcharge the springs.

CONTACT MAINTENANCEMANUAL HANDLE ADJUSTMENT Breakers subjected to frequent interruption of

high currents may eventually require replacementof their contacts. The general rule for determiningneed of replacement is the loss of one-half or moreof the mass of the contact tip material. Rougheningor light pitting of the contact surface does not indi-cate loss of ability to carry or interrupt current.

On manually-operated AICRbreakers, the closingsprings may be charged either by a single 135 de-gree clockwise handle stroke or up to four multiplestrokes of lesser swing. The following adjustmentprocedures should be performed using the single-stroke method. By so doing, proper multi-strokeoperation is assured.

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When contacts are replaced, they must be ad-justed to ensure that the proper amount of force is

Referring to Fig, 13 of GEK-7310, the manual developed between the movable and stationaryhandle adjustment is made via adjustable link (16) ,The length of this link is controlled by turning a the "wipe" adjustment. "Wipe" is the distancedouble-ended stud in its center, A hex section in through which the stationary contacts move when themid-stud can be engaged by an open-end wrench, breaker closes . It is measured between the pointWhen looking down on the breaker, turning the of contact on a stationary contact when the breakerwrench clockwise lengthens the link, The opposite is open, and the position of the same point when themotion shortens it. The range of adjustment is 300 breaker is closed. The actual wiping motion isdegrees. In the confined space available, each greater because the contacts over-travel . "Wiping"wrench stroke imparts 15 degrees movement. The imparts a sliding or "scrubbing" action to the con-

tacts .

con-tacts when the breaker is closed. This is called

best setting is approximately mid-range.6

Power Circuit Breakers, GEI-86134

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1. Movable contact arm .2. Stationary main contact3. Stationary arcing contact4. Contact spring5. Arc runner

Fig. 5. AKR/AKRU-SO contact structure(arc quencher removed)

The wipe adjustment influencesproperarc trans-fer during interruption of fault currents. ’’Transfer"of the arc is its forced sequential movement fromthe intermediate contacts to the arcing contacts tothe arc runner and finally to the arc quencher whereit is dissipated and extinguished. It is recommendedthat contact wipe be checked periodically duringnormal maintenance inspections.

CAUTION: BEFORE DOING ANY OF THEFOLLOWING CONTACT ADJUSTMENTAND REPLACEMENT WORK, MECHAN-ICALLY DISCONNECT THE CLOSINGSPRING FROM TltE MECHANISM CAMSHAFT, THE BREAKER CAN NOW BE"SLOW -CLOSED" USING THE MAINTE-NANCE HANDLE ,

1. Movable contact arm2 . Stationary main contact3 . Stationary arcing contact

Fig. 6 , AKR-30H contact structure

the first two contacts serve as the arcing contactsand the bottom three are the mains. There are nointermediate contacts .

The contact assembly for the AKR-30H breakeremploys the same AKR/AKRU-30 configuration, butadds a fourth stationary main contact at the bottom.See Fig. 0.

The following wipe adjustment procedure is ap-plicable to all AKR-30 types:

1. Open the breaker, remove arc quenchers.2. Arrange the breaker for slow-closing as de-scribed on page 15 of (3EK-7310.3. Using the ratcheting maintenance handle,

slow-close the breaker.4. Select one pole and, using a flat or wire feeler

gage, measure the gap between the top contact andits pivot stud as shown in Fig. 7 . As necessary,adjust the gap to 0.060 ± 0.020 inch by turning thewipe adjustment stud. .

5. Repeat this procedure on the other two poles.6. Trip the breaker .

oCONTACT ADJUSTMENT Types AKR-30, 30H

and AKRU-30The contact arrangement of the 800 ampere

frame AKR and AKRU-30 breakers differs signi-ficantly from that of the AKR-50 frame size. Eachpole consists of a single movable contact arm actingagainst five stationary contacts, arranged verticallyas shown in Fig. 5 . Proceedingfrom top to bottom,

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GE/-86J34, Power Circuit Breakers

@fe\ ADJUST GAP TO0.060n ± . 0,020"WITH BREAKER CLOSED CONTACT ADJUSTMENT Type AKRT-50

/ IThe contact structure of this 2000A breaker is

conceptually identical to the 1600A AKR-50 exceptthat it employs eight stationary main contacts in-stead of six. Constructionally, however , the upperstud assembly, movable contact arms and pivotblock are unique to the AKRT-50. See Figs, 8and 9 .

PIVOTSTUD

The two movable contact arms are pin-coupledto a metal driving link whose opposite end isthreaded and screws directly into the insulatinglink. This arrangement omits the wrench-operatedwipe adjustment stud provided on the AKR-30 and-50 frames. Instead, wipe is adjusted by detachingthe driving link from the movable contact arms andthen rotating it with respect to the insulating link.

i.:STATIONARYCONTACT

Fig. 7. AKR -30 wipe adjustment - view fromtop of breaker

CONTACT ADJUSTMENT

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Types AKR-50, 50Hand AKRU-50

Use the following procedure toperform wipe ad-justment:

1. Open the breaker, remove arc quenchers.

On the AKRT-50 the proper amount of contactwipe exists if , on a Closed breaker , all of the sta-tionary main contacts have moved away from theirstops. This condition can be checked visually byremoving the arc quenchers, closing the breakerand verifying that all eight stationary main contactsare "lifted off" their stops . Should wipe adjustmentappear necessary, proceed as follows:2. Arrange the breaker for slow-closing, as de-

scribed on page 15 of GEK-7310.1. Open the breaker.

3. Select one pole of the breaker and place a thinsheet or strip of tough irfsulating material, such asmylar, over the stationary arcing and intermediatecontacts. This strip should be about two incheswide and must prevent the arcing and intermediatecontacts from making contact when the breaker isclosed.

4. Using the ratcheting maintenance handle,slow-close the breaker with the insulation held inplace , Examine the insulation to make sure it"over-hangs" below the intermediate contacts.

5. Attach a continuity checker (bell-set or light)between the upper and lower stud ,

6. Facing the breaker, turn the wipe adjustmentstud clockwise until the checker indicates that themain contacts have parted. An open-end wrenchfits the hex section on the stud ,

2. Arrange the breaker for slow-closing as de-scribed on page 15 of GEK-7310.

3. Selecting one pole, drift out the coupling pinand detach the driving link from the movable con-tact arms.

;;4. Screw the driving link completely into the in-

sulating link .5. Back out the driving link two and one-half

turns. Exceed this by whatever amount is neces-sary to properly position the link within the movablecontact arms. f

6. Install the coupling pin and retainer rings.) )

7. Using the maintenance handle, slow-close thebreaker and observe that all eight stationary maincontacts move away from their stops. If this con-dition is not achieved, open the breaker, again re-move the coupling pin and back out the driving Unitan additional half turn.

7. Turn the stud counterclockwise until the maincontacts just touch.

8. From this point, advance the stud counter-clockwise 270 degrees . This will be 4-1/2 flats .

9 . Trip the brealee r, remove the insulatingstrips .10 . Repeat the above procedure on the other two

poles.

8. Reassemble, reclose thebreaker and recheckwipe.

9. Repeat the above procedure on the other twopoles.

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Power Circuit Breakers, GEl-86134

1. Movable contact arm2. Stationary main contact3. Stationary intermediate contact4. Stationary arcing contact5. Driving link6. Insulating link

I 7. Coupling pin

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Fig, 8, AKRT-50 contact structure

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DRIVINGL I N K

Fig. 9, AKRT ~50 Movable contact pivot block

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GEI-86134/ Power Circuit Breakersi

puller can be fashioned by forming a hook on theend of a length of 1/16-inch diameter steel wire.

The two movable contact arms (4) are removedby drifting out pin (10) connecting them to the in-sulated coupling (11). Right angle tru-arc pliersare needed to remove and replace the tru-arc re-tainer on the end of the pin.

Next, remove the fastening screws, washerssprings and pivot pin from; the pivot below. Whenreplacing the arms ensure that all spacers, springsand washers are returned to their original position .Tighten the two bolts in the contact arm pivot.

CONTACT REPLACEMENT Types AKR-30, 30Hand AKRU-30

The stationary contacts (arcing and mains) of theAKR-30 breaker frames are replaced in identicalfashion to that employed for the intermediate andmain stationary contacts of the AKR-50. To do sohowever, it is necessary to first remove the arcrunner by removing its three holding screws.

Replacement of the single movable contact armis accomplished in like manner employed for theAKR-50 breakers, i.e. , remove and replace thecoupling pin, pivot pin, etc , , as described below.

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AKRU-30 and -50 FUSED BREAKERSCONTACT REPLACEMENT Types AKR-50, 50H,AKRU-50 and AKRT-50

Except for the open fuse lockout device and theintegrally-mounted fuses on the upper studs, theAKRU-30 and -50 breakers are identical to the un-fused AKR-30 and -50 models. Overcurrent tripdevices are the same for both types.

Referring to Fig. 17 of GEK-7310, arcing con-tacts (1) are released by removing the arc runner(5) and the arcing contact pivot (6). When reassem-bling, make sure' that the insulating spacers on theends of the arcing contact pin (7) and the insulatingwashers (8) under the lower arc runner fasteningscrews are replaced.

Intermediate (2) and main contacts (3) are re-moved by disconnecting their springs. The endpieces on the springs (9) have a small hole for in-serting a spring puller . While holding the contact,pull the spring and lift it off the end of the contact ,Replace the contact by* holding it in position (innerend behind the contact stop) while extending andengaging the spring on the outer end . A suitable

Fuse Sizes and Mounting

Table 3 lists the range of fuse sizes availablefor these breakers. The Class L fuses are mountedas shown in Fig, 10. Other than the 800A size,which has a single mounting hole per tang, each Lfuse tang has two holes sized for one-half inch bolts.

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Class J fuses rated 300 thru 600A have onemounting hole per tang. The 300, 350 and 400Asizes require copper adapter bars per Fig. 11.!

TABLE 3GE CLF FUSES FOR AKRU BREAKERS

i

NEMAFuseClass600V60 Hz

MeltingTime-currentCurves

BreakerType

AKRU- Cat. No.AmpereRating

30 50A 300* GF8B300 GES-8004

i350* 350400* 400

A 450 450 i

A500 500600 600800 800 GES-8005

1000 1000l I1200 1200xz 1600 16002000 2000

Special 2500 GF9F2500AK 183B7832V-*Mounting adapter required - see Fig. 11

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Power Circuit Breakers, GE 1-86134.

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on AKRU-30 and -50 breakersp;

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GEI-86134, Power Circuit Breakersi

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2. Disconnect Key3. Heat Sink4. Upper Barrier5. Primary Disconnect

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Fig. 12. AKRU-50 breaker with special 2500A fuseM

•i 4. Remove the heat sink (3) ,t Special 2500A Fuse for AKRU-50

This fuse provides a melting time-current char-acteristic that coordinates with 1600A trip devices.Compared physically with a 2500A NEMA Class Lfuse, the special fuse is more compact (shorter);its tangs are specially configured and offset toachieve the required pole-to-pole fuse spacing; aspecialprimary disconnect assembly mounts directlyon the outboard tang of the fuse . Considering theirunique mounting provisions, when replacing thesefuses the following procedure should be adhered to(Refer to Fig. 12):

1, Remove the primary disconnect assemblyfrom the fuse tang, accomplished by first looseningthe two keys (2) via their holding screw and pullingthem upward and out. After the keys are removedpull the disconnect assembly off the end of the fusetang.

5. Remove the fuse .J- 6. Install the new fuse by reversing the dis-

assembly procedure. Ensure that the mating facesof the fuse and heat sink are clean.\

i< CAUTION:

FUSE IN THE LEFT POLE ( FRONTVIEW) OF THE BREAKER, NOTE PAR-TICULARLY THAT THIS FUSE ISMOUNTED DIFFERENTLY THAN THEOTHER TWO FUSES, AS SHOWN INFIG , 14, FOR THIS PHASE THE FUSEIS ROTATED 180 DEGREES ABOUT ITSAXIS $0 THAT ITS INBOARD TANG ISPOSITIONED BENEATH THE BREAKERSTUD. THIS TANG IS OFFSET WITHRESPECT TO THE OPPOSITE END (SEEFIG, 13, SO THAT ROTATING THE FUSEDOES NOT ALTER THE POSITION OFTHE PRIMARY DISCONNECT.

WHEN REPLACING THE

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NOTE: This removal does not disturb thedisconnect' s clamping force adjustment.

2 . Remove the upper barrier (4) .Open Fuse Lockout Device

. 3. Detach the inboard end of thefuse by remov-ing the two 1/2 inch - 13 bolts. A ratchet andsocket with a short extension will be required. Refer to GEK-7310, page 31.12

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Power Circuit Breakers, GEI-86134

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I I/ 1. BREAKER STUD/

/2. HEAT SINKi

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13. Mounting for special 2500A fuse onAKRU-50 breaker

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FRONT OF BREAKERFOR THIS POLE ONLY*FUSE IS ROTATED 180°TO POSITION TANGBENEATH BREAKER STUD

#* • *FUSE TANGSPOSITIONED ON TOPOF BREAKER STUD

BREAKERSTUD

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TANG BOLT HOLESIN USE

2500A. FUSECAT NO.

GF9 F 2500 AK Pty

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PRIMARY DISCONNECT ASSEMBLY ( SEE FIG.13 )MOUNTS DIRECTLY ON OUTBOARD FUSE TANG i!

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Fig. 14. Plan view of AKRU-50 breaker showing2500A fuse tang positions

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GEI-86134, Power Circuit Breakers

TYPE SST OVERCURRENT TRIP DEVICE

The SST is a solid-state, direct-acting, self -powered trip device system. Referring to the blockdiagram of Rig. 16 and the photograph of Fig. 15it comprises the following individual components:

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Programmer Unit - provides the comparisonbasis for overcurrent detection and delivers theenergy necessary to trip the breaker. Contains theelectronic circuitry for the various trip elements.Their associated pickup and time delay adjustments(set-points) are located on the face plate. Depend-ing on the application, programmer units may beequipped with various combinations of Long TimeShort Time, Instantaneous and Ground Fault tripelements. See Table 4 for available ratingssettihgs and trip characteristics,

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->The SST programmer units can be optionallyequipped with trip indicators (targets). These arepop-out, mechanically-resettable plungers locatedacross the top of the programmer’s front. Unitswith a ground fault element employ three targets:from left to right, the first is for overload, thesecond for short circuit (actuated by the short timeand instantaneous elements ) and the third for groundfault. The latter is omitted on units without groundfault.

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Fig. 15. SST Programmer unit

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Each target pops out when its associated tripelement operates to #ip the breaker . After a trip,the popped target must be reset by hand. However ,neglecting to reset does not affect normal operationof any trip element or prevent the breaker frombeing reclosed.

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TRIP COIL STATEI SWITCHi • *| CURRENT SENSOR-] I.

\! TAP I tCHANGERML ®--{ OVERLOADY I TARGETIeach pole mounts a singlesensor . coil (CT) which supplies the power and sig-nal inputs necessary to operate the trip system.Each sensor has four taps which provide field ad-justment of the trip device's continuous ampere NEUTRALrating; See Fig. 18.

The SST Ground Fault trip element operates onthe principle that the instantaneous values of cur-rent in the three conductors (four on 4-wire sys- (Kjgg )terns) add to zero unless ground current exists.On SST’s equipped with Ground Fault, the groundtrip signal is developed by connecting each phasesensor in series with a companion primary windingon a ground differential transformer mounted in theprogrammer unit. Its secondary output is zero solong as there is no ground current.

Current Sensors (ii1 LONG TIME

DELAY1I!< i m f01

( LONG SHORT TIMEPICKUP &

DELAYi t : LOGIC

"OR"l?2' TIME < TPICKUP

i SHORTI CIRCUITI TARGET

N CT HSLI DIFFERENTIALTRANSFORMER INSTANTANEOUS

PICKUP

T J GROUNDTARGETI

GROUND FAULTPICKUP & DELAYI i

REGULATED46 VDC

POWER SUPPLY TiPROGRAMMER UNIT— »U

Fig. 16. SST Block diagram

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Power C/rcu/f Breakers, GE1-86134

1. Flux shift Trip Device2. Allen-head Screws3. Stud Connector4. Current Sensor

5. Tap Terminal Board6. Programmer Unit7. Clamp Bolt8. Sensor Stud

Fig, 17, AKR-5A-30 breaker with SST trip device

Application of the Ground Fault element on 4-wire systems with neutral grounded at the trans-former requires an additional, separately mountedsensor (Fig, 19) inserted in the neutral, conductor ;its secondary is connected to a fourth primarywinding on the ground differential transformer.See Fig,. 27. This "fourth-wire" neutral sensor isan electrical duplicate of the phase sensor, includ-ing taps. Therefore, when taps are changed on thephase sensors, those on the neutral sensor must becorrespondingly positioned.

Flux Shift Trip Device - a low-energy, electro-magnetic devicewhich,, upon receipt of a trip signalfrom the programmer unit, trips the breaker byactuating the trip shaft. See Fig. 22.

All components except the neutral sensor aremounted on the circuit breaker.. The phase sensorsar e located on the breaker’s back f rame. The pro-grammer unit and the flux shift trip device aremounted on the breakersfront frame. These com-ponents are interconnected by wiring harness anddisconnect plugs, as shown on the cabling diagrams(Figs. 25 and 26) .

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When used, the neutral sensor is separatelymounted in the bus or cable compartment of theswitchgear. In drawout construction, its output isautomatically connected to the breaker via second-ary disconnect blocks. See Fig. 20.o

15

GEI-86134, Power Circuit Breakers

600 - 1600 A

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300 “ 800 A

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100 - 300 AFig. 15. SST phase sensor with tap board

Fig , 19* SST Neutral sensorsTABLE 4

SST TRIP CHARACTERISTICSSST PROGRAMMER ADJUSTMENT RANGE (Set Points)X - Trip Rating

in Amperes-Sensor Tap GROUND FAULTShort TimeLong TimeFrameSize

(Amperes)BreakerType

InstantaneousPickup Pickup

®/ Multiple \ ( Multiple \\ oth ) V o f X )

Pickup TimeDelay

Band (4)(Seconds)

TimeDelay

Band ©(Seconds)

Pickup (-L) TimeSensorAmpere

Taps©Delay

Band ©(Seconds)

.4, .5, .6,,8, 1.0,1.2 (X)

100t 150, 225, 300-or —300, 400, 600, 800

3, 4, 6,6,8,10 (L)AKR-30 800

Maximum0,30

Intermed.0.165

Minimum0.065

Maximum0.35

Intermed.0.21

Minimum0.095

Maximum4, 5, 6,

8, 10, 12 (L).6, .7, .8,.9, 1.0,1.1 (X)

22 -or- .25, .3, .4,300, 400, 600, 800-or-600, 800, 1200, 1600

Intermed. .5, .6,AKR-50 1600 1.75, 2,2.25, 2.5,3, 4 (L)

10 .7 (X)Minimum

4.2, .25, .3,.4, .5,

•6 (X)

800, 1200,1600, 2000AKRT-50 2000

© Pickup tolerance is ±.9%© Pickup tolerance Is ±_ 10%

© Time delay shown at 600% of long time pickup setting (6L), at lower limit of band.© Time delay shown at lower limit of band.

(See pages 28, 29 and 30 for applicable time-current curves)

16V

f!Power Circuit Breakers, GEI-86134

IiTROUBLESHOOTING jif!qWhen malfunctioning is suspected, the first step

in troubleshooting is to examine the circuit breakerand its power system for abnormal conditions such

Iiitfa) Breaker tripping in proper response to over-

currents or incipient ground faults.b) Breaker remaining in a trip-free state due to

mechanical interference along its trip shaft.c) Inadvertent shunt trip activations.

!*I$£

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lIWARNING: DO NOT CHANGE TAPS ONTHE CURRENT SENSORS OR ADJUSTTHE PROGRAMMER UNIT SET KNOBSWHILE THE BREAKER IS CARRYINGCURRENT.

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! ;iOnce it has been established that the circuitbreaker can be opened and closed normally from thetest position, attention can be directed to the tripdevice proper. Testing is performed by either oftwo methods:

i iREAR VIEW “AKR "50 K

BREAKER -MOUNTED;

:> 1. Conduct high-current, single-phase tests onthe breaker using a high current-low voltage testset.* *

t

NOTE: For these single -phase tests , spe-cial connections must be employed for SSTbreakers equipped with Ground Fault, Anysingle-phase input to the ground differentialtransformer will generate an unwantednground fault" output signal which will tripthe breaker. This can be nullified either

i

i f.

EQUIPMENT -MOUNTED

by

(a) testing two poles of the breaker inseries, or

(b) Using the Ground Fault Defeat Cableas shown in Fig. 28. This specialtest cable energizes all the primarywindings of the differential trans -former in a self -cancelling, series-parallel connection so that its second-ary output is always zero .

&

SHORTINGSTRAP

2. Test the components of the SST system usingportable Test Set Type TAK-TSI (Fig. 21). Theapplicable test procedures are detailed in Instruc-tion Book GEIC-64454 and are summarized on thenext page.9 Fig. 20. Neutral sensor secondary disconnect

blocks

17

T.l'l-

fPower Circuit Breakers, GEI-86134

Icondary disconnect block. Also checkfor continuity from the breaker-mountedneutral secondary disconnect blockthrough to the female harness connector(terminals L and N).

FALSE TRIPPING - BREAKERS EQUIPPED WITHGROUND FAULT) i i - i

When nuisance tripping occurs on breakersequipped with the Ground Fault trip element, aprobable cause is the existence of a false "ground"signal. As indicated by the cabling diagram of Fig.26, each phase sensor is connected in series with aprimary winding on the Ground Fault differentialtransformer. Under no-fault conditions on 3-wireload circuits, the currents in these three windings

add to zero and no ground signal is developed.This current sum will be zero only if all threesensors have the same electrical characteristics.If one sensor differs from the others (i.e. , differ-ent rating or wrong tap setting), the differentialtransformer can produce output sufficient to trip thebreaker. Similarly, discontinuity between any

sensor and the programmer unit can cause a falsetrip signal.

If nuisance tripping is encounteredon any breakerwhose SST components havepreviously demonstratedsatisfactory performance via the TAK-TS1 TestSet, the sensors and their connections should beclosely scrutinized. ’ After disconnecting thebreaker from all. power sources,

a) Check that all phase sensors are the sametype (ampere range).

b) Ensure that the tap settings on all 3-phasesensors are identical.

:: i;

(3 ) If the breaker’s lower studs connect tothe supply source, then the neutral sen-sor must have its LOAD end, connectedto the source.

(4 ) Ensure that the neutral conductor iscarrying only that neutral current asso-ciated with the breaker’s load current(neutral not shared with other loads).>

e) If the precedingstepsfail to identify the prob-lem, then the sensor resistances should bemeasured. Since the phase and neutral sen-sors are electrically identical, their tap-to-tap resistances should closely agree.

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REPLACEMENT OF CURRENT SENSORS

Referring to Fig, 17, removal of individual SSTcurrent sensors is accomplished as follows:

a) Disconnect the breaker harness from the tapterminal board (5), removing cable ties asnecessary. Unfasten the terminal board fromthe breaker base.

b) At the rear of the breaker , remove the twoAllen head screws (2) to separate the studconnector (3) from the contact pivot block.c) Verify that the harness connections to the

sensors meet the polarity constraints indi-cated by the cabling diagram, i.e, , whitewire to COMMON, black wire to TAP,

{.

c) Loosen the clamping bolt (7) and remove thestud connector. Lift out the sensor and itstap terminal board.d) On Ground Fault breakers serving 4-wire

loads, check that the neutral sensor is prop-erly connected (see cabling diagram Fig. 27).In particular,(1) Verify that the neutral sensor has the

same rating and tap setting as the phasesensors.

NOTE; To provide more working clearanceto adjacentaccessories, it may sometimesbe necessary to remove the sensor stud(8) also. Bo this by removing its fourholding bolts, accessible from the rear ofthe breaker (see Fig, 20).0 (2) Check continuity between the neutral

sensor and its equipment-mounted se-i

19

.1 .. .^^SiWl̂ SK^aSS :-Vi .

GEl-86134, Power Circuit Breakers

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*5£

SST/ECS test set, cat. wo. TAK-TSlFig. £1.

fCAUTION:ffARMSSS CONNECTOR FROM THE PRO-GRAMMER UNIT ON A BREAKER THATIS ENERGIZED AND CARRYING LOADCURRENT. 27//S WILL OPEN-CIRCUITTHE CURRENT SENSORS , ALLOWINGDANGEROUS AND DAMAGING VOLT-AGES TO DEVELOP.

NEVER DISENGAGE THEUSING THE SST TEST SET */ *

The TAK-TSl Test Set is a portable instrumentdesigned for field-checking the time-current char-acteristics and pickup calibration of the SST'svarious trip elements. It can verify the ability ofthe Flux-Shift Trip Device to trip the breaker andin addition, includes means for continuity checkingthe phase sensors. Test scope:

1. Verify the time-current characteristics andpickup calibration of the various trip elements.

2. Verify operation of the SST target indicatorson programmer units so, equipped."B" - Complete Trip Device System. For thesetests, the programmer unit must be mounted onthe breaker and connected to its wiring harness.Test scope:

1. All "A" tests previously described, plus pro-vision for optionally switching the programmer’soutput to activate the Flux-Shift Trip Device andverify its operation by physically tripping thebreaker.

2. Check phase sensor continuity.In the event that any component of theSST system

does not perform within the limits prescribed intest instructions GEK-64454, it should be replaced.

WARNING': BEFORE CONNECTING THETEST SET TO THE BREAKER TRIP DE-VICE SYSTEM, ENSURE THAT THECIRCUIT BREAKER IS COMPLETELYDISCONNECTED FROM ITS POWERSOURCE. ON DRAWOUT EQUIPMENT,RACK THE BREAKER TO ITS DISCON -NECTED POSITION. VERIFY THAT THEBREAKER IS TRIPPED.

I

Either of two test modes may be employed:

"An - Programmer Unit Only. These tests areconducted with the programmer unit disconnectedfrom the breaker. During test, the unit can remainattached to the breaker or may be completely re-moved from it.4

18

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