INSTRUCTIONS

GEI-I-1268 J

PERCENTAGEDIFFERENTIAL RELAYS

Ty p e sIJD52A 1JD53C1iD52B IJDS3D

GENERAL’ ELECTRiC

Percentage Differential Relays Type IJD

COVER

Figure 1. (8007207) Type Type IJD53A Relay Disassembled

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PERCENTAGE DIFFERENTIAL RELAYS

TYPE liD

INTRODUCTION

Type

IJD52ALTD 52 BIrD53CIJD53D

Elements

313

The Type ISD relays comprise a group that isused for differential protection of alternating current equipment. There are two general types - -thoseused for generator and reactor protection and thoseused for transformer protection. Both of these typesare available in e it he r the one -or the three -unitcases. Other variations suchas current ratings andminimum operating current will be covered byspecific model numbers under these types.

The case of these relays is suitable for eithersurface or semiulush panel mounting and an assortment of hardware is provided for either mounting.The cover attaches to the case and also carries thereset mechanism when one is required. Each coverscrew has provision for a sealing wire.

The case has studs or screw connections atboth ends or at the bottom only for the externalconnections. The electrical connections betweenthe relay units and the case studs are made throughspring backed contact fingers mounted in stationarymolded inner and outer blocks between which nestsa removable connecting plug which completes thecircuits. The outer blocks, attached to the case,have the studs for the ext e r n a 1 connections, andthe inner blocks have the terminals for the internalconnections.

The relay mechanism is mounted in a steelframework called the cradle and is a complete unitwith all leads being terminated at the inner block.This cradle is held firmly in the case withalatch atthe top and the bottom and by a guide pin at the backof the case. The cases and c r a dies are so constructedthat the relay cannot be inserted in the caseupside down. The connecting plug, besides makingthe electrical Connections between the respectiveblocks of the cradle ar.d case, also locks the latch inplace. The cover. w[ich is fastened to the case bythumbscrews. holds tie connecting plug in p!ace.

To draw out the relay unit the cover is first.r(’m.)vL-d. tad the olug drawn out. Shorting bars arepr “ideci tn the case to short the current transformer circuits. The latches are then released, andthe relay unit can be easily drawn out. To replace

the relay unit, the reverse order is followed.

Aseparatetestingplug can be inserted in placeof the connecting plug to test the relay in placeon the panel either from its own source of currentand voltage, or from other sources. Or, the relayunit can be drawn out and replaced by another whichhas been tested in the laboratory.

Figure 2. (K-6400174_o) Principle of Differential Protection

PRINCIPLE OF DIFFERENTIALPROTECTION

WhenaY-coimected a-c generator is operatingproperly the currents inthe three conductors at thejunction are, of course, equal to the currents in thecorresponding line conductors. Now, if the systemis grounded, either at this junction or at some otherpoint, then the equality of the currents will be disturbed if a ground fault occurs in one of the generatorwindings. Protectionagainst such faults can beafforded by a relay which compares the magnitudesof the twocurrents ineach phase and closes its con

tacts whenever the ratio of the larger to the smallerexceeds some predetermined value. Fig. 2 showsschematic connections for the application of such arelay. It is evident that no current will flow through

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For Protecting Outline & P.D. Fig.

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Percentage Differential Relays Type LTD

the operating coil as long as the CT secondary currents are equal and flow in the same direction.

In order to apply the above principle to the protection of transformers, it is necessary to providetaps on the two coils in such away as to compensatefor the inequality of the corresponding phase currents under normal conditions. This will be discussed more fully in the section on transformerrelays.

A certain amount of caution must be used inselecting current transformers for use with Type IJD

relays. if the CT error on through faults exceedsthe percentage slope characteristic of the relay thenfalse tripping may occur. For instance, if the relayhas a 10 percent slope characteristic, the two secondary currents should not differ by more than 10percent of the smaller when maximum fault currentis flowing.

To help prevent current transformer errorsfrom being excessive, it is recommended that burdens imposed be kept to a minimum. It is preferable to have no burden other than that of thedifferential relay.

RECEIVING, HANDLING AND STORAGEThese relays, when not included as a part of

a control panel, will be shipped in cartons designedto protect them against damage. Immediately uponreceipt of the relay, an examination should be madefor any damage sustained during shipment. If injuryor damage resulting from rough handling is evident,a claim should be filed at once with the transportationcompany and the nearest Sales Office of the GeneralElectric Company notified promptly.

Feasonable care should be exercised in unpack-

ing the relay in order that none of the parts areinjured or the adjustments disturbed.

if the relays are not to be installed immediately,they should be stored in their original cartons in aplace that is free from moisture, dust, and metallicchips. Foreign matter collected on the outside ofthe case may find its way inside when the cover isremoved and cause trouble in the operation of therelay.

GENERATOR AND REACTOR RELAYS

DESCRIPTI ONThe Type IJD52A relay is a single unit genera

tor differential relay. The Type IJD52B relay hasthree units, each of which is equivalent to that ofthe IJD52A. The induction unit of these relaysconsist of two coils assembled on laminated-ironU-magnets in such a way as to produce torque on adisk when current flows through them. The diskshaft carries a contact which is intended to energize the trip coils of two breakers.

A seal-in element is provided on each unit withits coil in series and its contacts in parallel with thecontacts of the induction unit. When the seal-in unitpicks up it raises a target into view. This targetlatches and remains in place until released by thereset button at the bottom of the cover.

OPERATING CHARACTERISTICSThe percentage slope characteristic of these

relays refers to the ratio Qf the differential currentto the smaller of the two phase currents, which willjust cause the relays to close its contacts. Fig. 3shows the operating characteristic for a relay with10 percent slope and 0.1 ampere minimum pickupcurrent.

The operating times for different values ofdifferential current and of load current are shownin Fig. 4. This time curve was taken with a 1/2time dial setting.

RATINGS

The restraining coils of these relays will carryfive amperes continuously without overheating. Theoperating coils of the models with 0.1-amperes minimum pickup will carry 0.6 amperes continuouslywithout overheating.

The current-closing rating of the contacts is30 amperes for voltages not exceeding 250 volts.The current-carrying ratings are affected by theselection of the tap on the target and seal-in coilsas indicated in the following table. When two tripcircuits are closed, these limits are for total current.

Amperes, AC or DC

Function 2-Amp Tap 0.2 Ampp

Tripping Duty 30 5Carry Continuously1 4 0.8

The 2-ampere tap has a d-c resistance of 0.13ohms and a 60 cycle impedance of 0.53 ohms whilethe 0.2-ampere tap has a 7 ohm d-c resistance anda 52 ohm 60 cycle impedance. The tap setting usedon the seal-in element is determined by the currentdrawn by the trip coil.

The 0.2-ampere tap is for use with trip coilsthat operate on currents ranging from 0.2 up to 2.0amperes at the minimum control voltage, If this

4

Percentage Differential Relays Type liD

tap is used with trip coils requiring more than 2amperes, there is a possibility that the 7-ohm resistance will reduce the current to so low a valuethat the breaker will not be tripped.

The 2 -ampere tap should be used with trip coilsthat take 2 amperes or more at minimum controlvoltage provided the tripping current does not exceed 3é amperes at the maximum control voltage.If the tripping current exceeds 30 amperes an auxil -

iary relay should be used, the connections beingsuch that the tripping current does not pass throughthe contacts or the target and seal-in coils of theprotective relay.

BURDENSThe burdens of the two coils at 60 cycles ar’

as follows:

r I Power 1Coil Amp Volt-amp Ohms Factj

Restraining I 5.0 17.55 0.7 0.27rating J.6 j 26.1 72.Sj 0.27

Of course there is no current flow through theoperating coil under normal conditions, hence thehigh burden is not usually objectionable.

CURRFNT FROM GFN. TC BUS.

Figure 3. (K.-6375795-l) Operating Characteristics of Type IJD52A and l1D52B Relays with 10 Per Cent Slope

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Figure 5. (K-h2O9677-3 Type IJD52A Relay, InternalConnections (Front View)

Figure 7. (K-6154157-4) Differential Protection of aGenerator using Type IJD52A Relays

Figure 6. (K-6209678-2) Type IJD52B Relay, InternalConnections (Front View)

Figure 8. (K-6154219-3) Test Connections for theType IJDS2B Relay

Percentage DiPerential Rela’i IJD

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Percentage Differential Relays Type LTD

TRANSFORMER RELAYS

DESCRIPTION

The Type 11D53C is a single unit transformerdifferential relay. It is usually applied for differential protection of a single-phase transformer, orin a set of three for protection of a three-phasetransformer. The Type 1JD53D has three unitssimilar to that of the Type IJD53C, with their contacts connected in parallel. The single unit relayis shown on the cover page and in Figs. 1, 9, and 10.

The induction unit of these relays consists oftwo coils assembled on laminated U-magnets in sucha way as to produce torque on a disk when currentflows through them. The disk shaft carries a contcr which is intended to complete the trip circuitsI or two breakers.

A seal-in element is provided on each unit toprotect the main contacts. When the seal-in picksup it operates a target which remains visible untilreleased by the rest button at the bottom of the cover.

OPERATING CHARACTERISTICS

The characteristics of these relays are suchthat when the current in the two circuits are in thesan]e ratio as the two tap-plug position numbers,therc is no operatingtorque produced. A numericalexample of this statement will help to t3xplain this.

Suppose the tap plugs of a Type IJD53C relay areset in the 3.2 tap of the upper tap block and in the5.0 tap of the lower tap block. Now, with polaritiesof the currents as indicated in the diagram with thecurves of Fig. 13, assume that 3.2 amperes flow outterminalS, 5.0 amperes interminal7, andthe differ-

ence,1.8amperes,outterminal6. Under these conditions no torque will be produced by the operatingU-magnet, but considerable torque will be producedby the restrainingU-magnet. Furthermore, as longas the two currents in terminals 5 and 7 remain inthe ratio of 3.2 to 5 and are 180 degrees apart intime phase, there will be no operating torque.

These relays are built with twotypes of percent-slope characteristics; 25% slope, and 50% slope.The significance of the percent -slope characteristiccan best be understood from an extension of the example above. Takingthe25%slope relays as an example, suppose that the current into stud 7 increasesto 125% of 5.0 orto 6.25 amperes whfle the currentout of stud 5 remains at 3.2 amps, this representsa condition of 25% unbalance. The same thing wouldbe true if the 5 amp value were held constant whilethe 3.2 value was increased 25% or to 4 amperes.

It should not be inferred from this discussionthat the relay will necessarily close its contactsunderthe conditions dscribedas 25% unbalance. Atlow current values considerable more unbalance isnecessary to overcome the effect of the spring.However, at current values of twice tap value andabove, the unbalance required for operation will notgreatly exceed 25%. Fig. 11 and 12 show these relationships graphically for currents several timesrated values. In explaining these graphs, the sametap ratio of 3.2/5willbe used. If 12 were 50 amperesthere would be no operating torque developed if

= 3.2 X 50 = 32 amperes. This relationship is

shown by the dotted lines running diagonally acrossthe graphs in Fig. ii and 12. If I were to increaseabove the no torque condition by 25%, it would now

UPPER TAP PLATE

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Figure 10. (8007208) Type IJD53C Relay Mounted inCradle (Rear View)

Figure 9. (8007205) Type IJD53C Relay Mounted inCradle (Front View)

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Percent age Dif[i.rcntial Relays Tyc [in

be 1.25 x 32 = 40 amps. Fig. ii shows this condition for values of 12 between 0 and 70 amps. 11 onthe other hand, Ii were to r e main constant at 32amps and 2 were to increase 25%, 12 would go to50X1.25= 62.5 amps. Fig. 12 shows this conditionfor values of I between 0 and 70 amperes. Thesecurves show the i - n i ni u rn current on the ordinal.e to close the relay contacts for a given current on the abscissa when the various tap ratiosshown are used. The time characteristic is shownin Fig. 13.

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Fig. 14 and 15 show curves for the relays with50% slope characteristics.

MINIMUM PICKUP

These relays are adjusted at the factory to closetheir ront acts at 40 percent of tap value in one circult with no current in the other. This pickup maybe increased by means of the control spring to 125per cent of tap value as described under ‘Adjustments.

TAPS

11 12

5. 0—4 .6

Fuure 11. (64O1h9,Sh.l 2fl Jperatin$ Characteristics of Type L1T)53C and IJD53D RelaysWith 25 alope When I is Excessive.

CURRENT DIFFERENTIAL RELAY1JD5381 FOR TWO—WINDINGTRANF.__PROTECTION.UINIMU’.Y VALJ[S OF lj 10CLOSE CONTACTS wITH EXCESSCURRENT IN t CIRCUIT TORARE RATIO CF 1 TO 1225GREATER THAN NORRAL

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Percentage Differential }eIays Type 1JD

RATINGSThe standard models of these relays have a tap

range of 3.2 to 8.7 amperes. Any of the circuits

will carry twice the tap setting or 10 amperes,whichever is less, continuously on any current tap

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without overheating.

The current ratings of the contact circuits arediscussed fully in the section on generator relays.This discussion applies to the transformer relaysalso.

Figure 12. (K (54O0lO9Sh23l) iperating Characteristics of Type IJD53C and 1J1053D Relays

With 25 Slope When 12 is Excessive.

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Pc rceritage Differential Rel.iy Type [.rD

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Figure 13. (K-6400171-4) Typical Time-Current Characteristics of Type 1J1153C and IJD53D Relays.

BURDENSBurdens for the standard toils at five amperes

and rated frequency are given in the table on theright. Operating coil burdens are for the minimumcurrent tap, 3.2 amperes, while restraint coil burdens are withthe 5.0 ampere tap on both tap blocks.

Impedance of the operating coil on any other tapis inversely proportional to the square of the tapvalue. The impedance of the restraint circuit withunequal tap settings is difficult to calculate, but ingeneral will be quite low.

Freq. Coil Volt-amp Imp. Ohms PF60 Operating 20.5 0.82 0.33

Restraining 1.1 0.043 0.94

50 Operating 17.5 0.70 0.35Restraining 1.0 0.041 0.96

25 Operating 10.5 0.42 0.41Restraining 0.9 0.037 0.98

ii

Perceitage Differential Relays Type IJD

Figure 24. (K-6400379,Sh.l [1)) Dperating Characteristics of Type IJD53C and IJES3D Relays

With 5O Slope When lis Excessive.

INSTALLATION

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LOCATION

T1e lcca. ion should be clean and dry, free from

dust a !d I-(rssi c vibration, and we 11 lighted to

facjl’.ite inspection and testing.

MOUNTING

The relay should be mounted on a vertical sur

face. The outline and panel diagrams are shown in

Fig. 21 and 22.

12

Percentage Differential Relays Type lID

0

Figure 15. - 4u037l3,Sh.2 31) )perating Characteristics of Type LJD53C and IJD53D belaysWith 50 blOpE When 19 is Excesjv.

CONNECTIONSGNERATOR RELAYS

Internal connections for the Type IJD52A areshown in Fig. , and for the Type IJD52B in Fig. 6.

Typical external connect ions for the Type11D52A are shown in Fig. 7. It will be noted thatcontacts are provided for closing two trip circuits,namely the line breaker andthe field breaker. Connections for the Type IJD52fl will correspond tothese except that the stud numbers will be different.

13

Percentiwe Differential Relays Type IJD

TRANSFORMER RELAYS

Internal connections for the Type 13D53C are

shown in Fig. 16 and for the Type IJD53D in Fig. 17.

Typical external connections forthe type IJD53D

are shown in Fig. 18 and 19. It will be noted that

this figure shows connections to be used when the

transformer bank is Delta-Wye, or Wye-Delta. IS

the hank is Wye-Wye with grounded neutrals, then

the connections shown in Fig. 7 for the generator

relay can be applied to the transformer relay pro

vided the transformer consists of three, single—

phase transformers. This connection cannotbeused

if a three-phase core-type transformer is used since

the case acts in a manner similar to the delta insofar

as it is a source of zero-phase sequence current.

Also, the wye.-wye arrangement cannot have a delta

winding, even though that winding is not used for

load purposes, for the same reason.

External connections for the Type IJD53C relay

should correspond to the connections for phase 2

in Fig. 18.

In each case, the smaller of the two secondary

current should pass through the right-hand stud on

the relay (back view), that is, stud 2, 5, or 8.

There ,is a useful rule which can be applied to

determine whether delta orwye current-trans

former connections should be used for differential

re1ayin of a 3-phase transformer bank composed of

three similar single -phase transformers, each hay-

trig two or more windings. This rule is as follows:

The current transformers in [he leads to a wye

connected winding should be connected in delta;

current transformers in the leads to a delta-con

nected winding should be connected in wye.

Since there are several ways of connecting the

current transformers in wye or delta, the following

additional rule should be noted: Make the delta

connection of the current transformers a replica of

the delta connection othe power transformers; the

wye connections of the current transformers should

be a reversal of the wye connection of the power

transformers.

GROUND CONNECTIONS

One of the mounting studs or screws should be

permanently grounded by a conductor not less than

No. 128 FS gage copper wire or its equivalent.

ADJUSTMENTS

TARGET AND SEAL-IN ELEMENT FOR BOTH

TYPES

For trip coils operating on currents ranging

from 0.2 up to 2.0 amperes at the minimum control

voltage, set the target and seal-in tap plug in the

O.2-ampere tap.

For trip coils operating on currents ranging

from 2 to 30 amperes at the minimum control volt

age, place the tap plug in the 2-ampere tap.

The tap plug is the screw holding the right-hand

stationary contact of the seal-in element. To change

the tap setting, first remove the connecting plug.

Then, take a screw from the left-hand stationary

contact and place it inthedesiredtap. Next remove

the screw from the other tap, and place it in the

left-hand contact. This proced’ire is necessary to

prevent the right-hand stationary contact from

getting out of adjustment. Screws should not be in

both taps at the same time as pickup for d-c will

be the highter tap value and a-c pickup will be in

creased.

GENERATOR RELAYS

No adjustment of the relay is necessary other

than the setting of the target and seal-in element

tapplugdescribedabove. Howevei-,the relay should

be inspected for any loosening of the screws that

may have occurred during shipment.

TRANSFORMER RELAYS

These relays have been adjusted at the factory

to operate as indicated by the characteristic curves.

However, it is necessary to make the proper tap

selections for the particular application. The taps

chosen should be such that the ratio of tap settings

lsequaltothe ratio of currents to the corresponding

tap blocks. Itis also desirable that the tap settings

should be equal as nearly as possible to the respec

tive currents which will flow under normal condi

tions. The normal currents at the relay terminals

can be readily calculated from the current trans

former ratio and the normal load on the power trans -

formers.

The tap settingswill, of course, usually be made

before the relay is energized initscircuit. If, how

ever, it isnecessaryto change the tap settings after

the relay has been installed, the connection plugs

shouldberemovedfrom the case before proceeding.

When the tap plugs are inserted into the tap blocks,

caution should be exercised to screw them all the

way down until the lock washer is flattened between

the plug and plate. These precautions are necessary

to avoid opening the current transformer secondary

circuits.

A further adjustment that may be necessary at

the time of installation is the setting of minimum

pickup current. The relays are adjusted at the

factory so that with no current in one circuit, 40 per

cent of tap current is required in the other circuit

to close the contacts. This value can be increased

by turning the c o nt r aT spring adjusting ring (see

Fig. 9) in a counter-clockwise direction. Pickup

should not be increased to more than 125 percent

of tap value, or the control spring may be damaged.

At the time of installation, the relay should be

inspected for any loosening of the screw that may

have resulted from vibration or rough handling

during shipment.

14

I’Figure 16. (K—6556496.-3) Type IJD53C Relay, Internal

Connections (Front View)Figure 17. (K-6556497-2) Type IJD53D Relay, Internal

Connections (Front View)

Figure 18. (K-6142O7-4) Differential Protection of Power Transformer Using a Type 1J053D Relay.

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Percentage Differential Relays Type IJD

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taA(PIMI IIAGWW & ISTOAIA1hiJ 111141141 loSIGIAIIOKS APPlY.

*111 - -III; FLP 1 F 111111515 APPlY ID JFO’D. 05110 STill lt.UPJ1S FIFtY TO

IIOYl. 511.3 4jA5 5 A I Ill ;PX31 1440 Ft ItIYtfliAY ,N 11111,141

11,1111 II ht&&MPl TO 1140)1 (1,110115 In AlLAY TArS. fl( 5114 APPIlIS

III flIt lit (10 OFLIIIP 01 SOFT, 4—7_Ill lit .11413 7-5—lI ill 1.0131(1

tOll 3; 0.30111 7; 7 11111,1.31 IlL PT 1411 111.30140 1(01 114)4 TOIJICt il

llhIUl HI Omit 1RA1l5l14H 11FF II 114.311111

Figure 19. (0264B0449-3) Differential Protection of a Power Transformer Using a Type IJD53D Relay

With Desensitizing Equipment.

OPERATION

Under certain circumstances, false operationmay occur when large external fault currents arecleared. This would be due to the sudden releaseof reverse torque on the relay shaft. If this troubleis encountered it probably can be corrected by oneor more of the following adjustments.

I. Increasing the disk travel by loosening thetwo set screws and turning the Textolite dial,mounted at the top of the shaft, counter-clockwise.The dial should not be turned beyond the numbertwo setting inscribed in the dial or to a positionwhere the slot in the disk is allowed to pass underthe pole of the operating coil. The relay will notoperate properly when the slot is under the polesince the two fluxes from the pole cannot inter-actin the disk because of the slotted separation.

The Type IJD relays have the time dial set andlocked at the factory. The types IJD52A and IJD52Bare set at the 0.5 time dial setting and the TypesIJD53C and 1J053D are set at the 0.8 time dialsetting. The 0.8 time dial setting is equivalent toa three-quarter inch travel at the periphery of thedisk.

2. Moving the drag magnet out from the centerof the shaft.

3. Increasing the wind-up of the spiral controlspring. This should not be increased more than90 deg. over the original factory setting.

DESENSITIZATIONAny of these adjustments will increase the

operating time on internal faults, and the third alsowill increase the minimum current required foroperation.

In some instances it may be that the maximumcurrent setting of these relays will not be highenough to prevent them from operating on magnetizing inrush current. If such a condition should exist,it is recommended that the IJO relay be used with anauxiliary desensitizing equipment consisting of anauxiliary relay, a potential transformer, and threeexternal resistors connected as shown in Fig. 19.

To facilitate the connection of the desensitizingequipment the relay is provided with an extra studwhich terminates at the junction of the two 5.0 amp.taps.

This permits the external connection of au.xiiary desensitizing equipment to the operating coilonly, without affecting the restraining torque. Whenthe desensitizing equipment is connected in thismanner, the pick-up value ol the relay is raisedthe same amount regardless of the direction fromwhich the transformer is energized.

The following table shows the factor by which

the nominal pickup must be multiplied when the de

sensitizing resistor 579A121 G—2 is connected as

described above. Fig. 19A shows the wiring

diagram and mounting outline for the resistor.

-- —

:j1 11111H(0 I

l;{I iH-- L:_

tn4L

FlJI1

fV1L

57-li

52-li

16

Percentage Differential Relays Type LID

.15 .15 .15 .15 .15 .15

REQUIRED JUMPER CONNECT TOOHMS RELAY

0.05 1 TO 3 2 TO4 1 AND 4

0.10 1T05 3T07 IAND70.20 1 TO 7 1. AND3

0.30 NONE 1 AND 3CONNECTIONS REFER TO ONE RESISTOR ONLY

Figure 19A. (O418AO999-3 Wiring Diagram and Mounting Outline for External Resistor

MOUNTING FIXTURE-1OWN IS FOR THREERESISTORS, ELECTRIC—ALLY SEPARATE

17

Percentage IDifferential R’1avs ‘l’vije IJD

RESISTOR OHMS J0.057 0.1 ro.2 0.3

MULTIPLIER 8.0 2.1 1.65

Since the resistance shui:tiug the operating coil

determines the pick—up value of the relay, it is im

portant that the lead resistance from the relay to the

desensitizing resistor be kept as low as possible.The auxiliary relay is time opening and instantaneousclosing, and its contacts are closed when the relay

is energized. The external resistors are connected

across the operating cods of the IJD relays throughthe contacts of the auxiliary relay. When thefirst transformer breaker is closed, the auxiliary

relay is energized from the potential transformersecondary, but does not open its contact immethately.

This permits a momentary raising of the IJD relaysetting as part of the current, which would normally

flow through the operating coils, is shunted through

the external resistors. When the contacts of theauxiliary relay open, the shunt circuit is removedand the IJD relay functions at normal rating.

The Type HDD Percentage Differential Relay,

with harmonic restraint is available for transformer

protection and is inherently Insensitive to inrush

current owing to its harmonic restraint feature.

MAINTENANCE

The relays are adjusted at the factory and it isadvisable not to disturb the adjustments. If, for anyreason, they have been disturbed, the following points

should be observed in restoring them:

DISK AND BEARINGS

The lower jewel may be tested for cracks byexploring its surface with the point of a fine needle.If it is necessary to replace the jewel a new pivotshould be screwed into the bottom of the shaft at thesame time. A very small drop of General Electricmeter-jewel oil, or fine watch oil, should be placedon the new jewel before ii is inserted. The jewelshouldbe turned up until the disk is centered in theair gaps, after which it should be locked in thisposition by the set screw provided for this purpose.The upper bearing pin should next be adjusted untilvery little end play can be felt; about .015 inch iscorrect.

CONTACT CLEANING

For cleaning fine silver contacts, a flexibleburnishing tool should be used. This consists of a

flexible strip of metal with an etched roughenedsurface, resembling in effect a superfine file. Thepolishing a c t i on is so delicate that no scratchesare left, yet corroded material will be removedrapidly and thoroughly. The flexibility of the toolinsures the cleaning of the actual points of contact.Sometimes an ordinary file cannot reach the actualpoints of contact because of some obstruction fromsome other part of the relay.

Fine silv.’r contacts should not be cleaned with

230

1 --- -

4 s-f,’ j2 0Pf0 ->

.

..P010 lOp 05,1

——____

‘I All 1*0 .011

:EJ—,) tj—•0.LV,111ll .-

——

—

— -

Figure 20. (K-6154218-1) Test Connections for the

Middle Unit of the Type 13D53B Relay.

knives, files, or abrasive paper or cloth. Knivesor files may leave scratches which increase arcingand deterioration of the contacts. Abrasive paper

or cloth may leave minute particles of insulatingabrasive material in the contacts and thus prevent

closing.

The burnishing tool described above can be

obtained from the factory.

PERIODIC TESTING

An operation test and inspection of the relay at

least once every six months are recommended. Test

connections are shown in Fig. 8 and Fig. 20.

RENEWAL PARTS

It is rrcommcnded t hat sufficient quantities

of renewal parts be carried in stock to enable theprompt replacenwnt of any that are worn, broken,or damaged.

When ordering renewal parts. address the near-

est Sales Office of the General Electric Company,

specify quantity required, name of part wanted, and

give complete name plate data, including serial

number. If possible, give the Ge tie ral Electric

Company requisition number on which the relay

was furnished.

Since the last edition, changes have been made in Figures 21 and 22.

13

Percentage Differential Relays Type IJD

9. 125232MM

PANEL DRILLINGFOR SEMI-FLUSH MOUNTING

FRONT VIEWPANEL DRILLING

FOR SURFACE MOUNTINGFRONT VIEW

TYPICAL DIM.INCHES

MM

Figure 21. (K—6209271 18)) Outline and Panel Drilling Diiriensions for Type IJD52A and IJD53C Relays

_____

6 625

____

•• 168MM ‘

(2) 5/16—18 STUDSFOR SURFACE MTG.

riAss

-j

___

I. 12529MM1/4 DRILL

4 HOLES6MM

STUDNUMBERING

975310 C) 000

0000010 8 6 4 2

BACK VIEW

5/8 DRILL2 HOLES

15MM—

--;---

4.406112MM

I-CU iiUT

CUTOUT MAY REPLACEDRILLED HOLES

8.812224MM

1 1 5629MM

172MM1

5 687144MM

.50012MM

(TYPICAL)

CASE-

VIEWFOR

5/16-18 STUD

19

Percentage Differential Relays Type IJO

A9 97525iMM

6 75171MM

PANEL DRILLINGFOR SEMI-FLUSH MOUNTING

FRONT VIEW

TP1CAL DM.INCHES

MM

.50012MM

(TYPICAL)

PA1[L DRILLINGFUR SURFACE MOUNTING

FPINT VIEW

Figure 22. (I(—6209276 f5J) Outline and Panel Drilling Dimensions for Type IJD52B and LJD53D Relays

____

C 625 SEMI-FLUSH

168MM -

PANEL LOCATION

1 0-324) 5/16—18 STuBSOR SURFACE MTG.

1917 15 131100000

20,312

516MM

CLASS

I_L - -

U 0

(.6) iO-3, X 3/EMTG. SCREWS

00018 16 24

012

STUDNUMBER INS

9753100000

0000010 8 6 4 2

BACK VIEW

CUTOUTS MAY REPLACEDRILLED HOLES

T19. 3255MM

19875504MM

2185MM

19. 7550

——

1 ,46837MM

-3/4 DRILL20 HOLES19MM

CASE

--4

_

VIEW SHOWING ASSEMBLY OF HARDWAREFOR SURFACE MTG. ON STEEL PANELS

5/16-18 STUD

BC-7197(200) GENERAL ELECTRIC METER AND CONTROL BUSINESS DEPT., MALVERN, PA 19355