0 InstructionsGE I -98338 E

SuPERSEDES GEI-98338D

TYPEGCY51A

MHO DISTANCE RELAYS

These instructions do nut purport to cover all details or variations in equipment nor to provide for every possiblecontingency to be met in connection with installation. operation or maintenance Should further information be desiredor should particular problems arise which are not covered sufficiently for the purchaser’s purposes, the matter shouldbe referred to the General Electric Company.

To the extent required the products described herein meet applicable ANSI, IEEE and NEMA standards; but nosuch assurance is given with respect to local codes and ordinances because they vary greatly.

(8035287)

GEI—98338

CONTENTS

INTRODUCTION 3APPLICATION 3RATINGS 4

Contacts 5Target Seal-in Unit 5

OPERATING PRINCIPLES 6N1 Unit 6N2 Unit 6ON3 Unit 7

CHARACTERISTICS 7N1 Unit 7M2 Unit 10ON3 Unit 12General 13

BURDENS 14Current Circuits 14Potential Circuits 14Ml Unit 15N2 Unit 15OM3 Unit 15

CALCULATION OF SETTINGS 16First Zone Setting 17Second Zone Setting 18Third Zone Setting 18Sensitivity Check 19

CONSTRUCTION 20Case 20

RECEIVING, HANDLING, AND STORAGE 21ACCEPTANCE TESTS 21

Visual Inspection 21Mechanical Inspection 21Electrical Checks — Mho Units 22Electrical Tests - Target Seal—in 25

INSTALLATION PROCEDURE 25Location 25Mounting 25Connections 25Visual Inspection 25Mechanical Inspection 26Portable Test Equipment 26Electrical Tests-Mho Units 26

Example of Mi Test 27M2 Tests 300M3 Tests 31

Electrical Tests - Seal-in Unit 31Overall Tests 31

PERIODIC CHECKS AND ROUTINE MAINTENANCE 32Contact Cleaning 32

SERVICING 32Control Spring Adjustment 33Ohmic Reach Adjustment 33Angle of Maximum Torque 34

RENEWAL PARTS 35

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MHO DISTANCE RELAY

TYPE GCY51A

INTRODUCTION

The GCY51A is a single-phase, three-zone, expanded-range, directional mhostep distance relay for transmission—line protection. Each relay covers arange of settings from 0.75 to 30.0 secondary ohms. Three GCY51A relays plusone suitable RPM or SAM timing relay will provide three—step distanceprotection against three—phase, phase—to—phase, and double-phase-to—groundfaults. A separate ground relay is required for single-phase—to-groundfaults. The GCY51A relays are also used in combination with other relays andpilot channels to provide high-speed protection in directional comparison andtransferred tripping schemes. The GCY51A relay comes in an L2 case andcontains one target seal—in unit per relay. The impedance characteristics ofthis relay are shown on the R-X Diagrams of Figures 17 and 18.

APPLICATION

The GCY51A relays may be applied wherever three zones of rnho-typedistance protection are required for multi—phase faults. This includesdirectional comparison and transferred tripping as well as straight distanceschemes.

The minimum fault current requirements for the three units of the GCY51Arelay may be obtained from the bullet—shaped curves of Figures 7, 10, and 13.The unit will operate if the line representing the impedance to the fault (inpercent of reach setting) intersects, within the bullet curve representingthat unit, with the three-phase fault current line. However, the bestoverall operation will be obtained for faults in the protected line section ifthe minimum current in the relay for a three-phase fault at the remote busexceeds the values given in Table I.

TABLE I

BASIC MIN. MIN. 3 FAULTUNIT REACH CURRENT

(P-N OHMS) (SEC. AMPS)

.75 8Mi 1.5 4

3.0 2

1.0 12M2 2.0 4

3.0 3

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The M1 and H2 units of these relays each have an angle of maximum torqueof 600 that can be adjusted in the field to 750, if desired. However, it isrecommended that the M1 unit be set at 600 because it will accommodate morearc resistance for close-in faults with the 600 setting than it will with the750 setting. This is particularly true for the shorter—reach settings. Forshort-reach settings it is also desirable to set the M2 unit on 60° so that itwill accommodate more fault resistance. This becomes more important in pilotapplications where the H2 unit operates in conjunction with the channel toprovide high-speed tripping, and so must operate for close-in faults.

When the GCY5IA is used in step—distance applications, the third zone CM3unit may be set with or without offset, looking either into the line section

or away from it, as desired. However, in directional-comparison pilot schemes

where the OH3 unit is required to initiate a blocking signal during externalfaults, it must he set with offset, and with its longest reach in the reversedirection, to insure positive high-speed operation to start and maintain theblocking carrier signal during external faults. The curves of Figure 14

indicate that the 0M3 unit with 100% tap setting and 0.5 ohm offset requires aminimum 3-phase fault current of 2 amperes to operate on a steady-state basisfor a zero-voltage fault.

In order to obtain maximum possible performance, it is suggested that theM1 and M2 units be set on the highest basic minimum-reach tap that willaccommodate the desired settings. Since the maximum transient overreach onthe M1 unit is 5% regardless of setting, this unit can be set to protect asmuch as 90% of the distance to the remote terminal

The section on CALCULATION OF SETTINGS provides a typical worked examplefor setting the GCY51A relay in a step-distance application. Figure 3 is anelementary diagram for three-step distance protection using three GCY51Arelays and one RPM11D timer.

RATI NGS

The Type GCY51 relay covered by these instructions is available for 120volts, 5 amperes, 60 cycle rating. The i-second rating of the currentcircuits is 225 amperes. The basic minimum reach and adjustment ranges of theM1, M2, and 0M3 units are given in Table II.

TABLE II

BASIC MIN. REACH RANGE ANGLE OF OFFSETUNIT ( (p-N OHMS) (cp-N OHNS’ MAX. TORQUE (p-N OHMS)

H1 0.75/1.5/3* 0.75/30 600**

H2 1/2/3* 1/30 600**

OH3 3 3/30 750 0/0.5

* Adjustment taps are set for 1.5 ohms (Mi) or 2 ohms (M2) basic minimumreach prior to shipment.

** The angle of maximum torque of the M1 and M2 units can be adjusted up to75°. The reach of the H1 unit will increase slightly; the reach of theM2 unit will increase to approximately 120% of its reach at the 600setting.

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It will be noted that three basic minimum-reach settings are listed forthe M1 and M2 units. Selection of the desired basic minimum reach for the Mlunit is made by means of two tap screws on a two—section tap block located onthe right side of the Ml unit subassembly (see Figure 1). The position ofthese screws determines the tap setting of the two primary windings oftransactor TR—1.

Selection of the desired basic minimum reach for the M2 unit is made bymeans of links on a terminal board located on the rear of the M unitsubassembly (see Figure 2). The positions of the two sets of links, eachidentified as A-B, determine the tap setting of the two current—operatingcoils of the M2 unit.

Selection of either 0 or 0.5 ohm offset for the 0M3 unit is made by meansof links on a terminal board located on the rear of the 0M3 unit subassembly(see Figure 2).

The ohmic reach of the M1, M2 or 0M3 units can be adjusted in 1% stepsover a 10/1 range for any of the basic minimum-reach settings listed in TableII by means of auto—transformer tap leads on the tap block at the right sideof the relay (see Figure 1).

Contacts

The contacts of the GCY51 relay will close and carry momentarily 30amperes DC. However, the circuit breaker trip circuit must be opened by anauxiliary switch contact or other suitable means, since the relay contactshave no interrupting rating.

Target Seal-in Unit

The 0.6/2 ampere target seal—in unit used in the GCY51 relay has ratingsas shown in Table III.

TABLE III

TARGET SEAL-IN UNIT

0.6 Amp Tap 2.0 Amp Tap

Minimum Operating 0.6 amp 2.0 ampsCarry Continuously 1.5 amps 3.5 ampsCarry 30 Amps for 0.5 sec. 4 secs.Carry 10 Amps for 4 secs. 30 secs.DC Resistance 0.6 ohm 0.13 ohm60 Cycle Impedance 6 ohms 0.53 ohm

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OPERATING PRINCIPLES

The mho units of the GCY5I relay are all of the four-pole inductioncylinder construction, in which torque is produced by the interaction betweena polarizing flux and fluxes proportional to the restraining or operatingquantities. The method of obtaining the mho characteristic for the N1 unitdiffers from that used for the N2 and ON3 units. Both schemes are describedbelow.

M1 Unit

The schematic connections of the N1 unit are shown in Figure 4A. The twoside poles, energized by phase-to—phase voltage, produce the polarizing flux.The flux from the front and rear poles, energized by the difference betweenthe secondary voltage of transactor TR-1 and a percentage of the same phase-to-phase voltage, interacts with the polarizing flux to produce torque. Thetorque equation can be written as follows:

Torque = KE (IZT1 — TE) cos (1)where:

E = phase-to-phase voltage CE12).I delta current (Ii - 12).

ZT1 transfer impedance of transactor TR-1 (designcon stant.

S = angle between £ and (IZj1 - E).K = design constant.T = auto-transformer tap setting.

That this equation ‘1) defines a mho characteristic can he showngraphically by means of Figure 5. The vector IZTT at an angle 0 determinesthe basic minimum reach of the unit for a particular tap setting of thetransactor TR-1 primary. Assuming finite values of E and (IZT1 — TE), thebalance point, torque = 0, will occur where cos S = 0, that is where the angleS is 900. The locus of the terminus of vector TE (point A in Figure 5) thatwill cause the angle 13 always to be 900 is a circle passing through the originand with the vector IZT1 as a diameter.

Considering further the diagram in Figure 5, we note that the angle 13 isless than 900 for an internal fault point C) and the net torque will be inthe closing direction (cos 13 is positive); and that the angle 13 is greaterthan 900 for an external fault (point D) and the net torque will be in theopening direction (cos 13 is negative).

M2 Unit

The schematic connections of the N2 unit are shown in Figure 48. The twoside poles, energized by phase-to-phase voltage, produce the polarizing flux.The flux in the front pole, which is energized by a percentage of the samephase-to-phase voltage, interacts with the polarizing flux to producerestraint torque. The flux in the rear pole, which is energized by the twoline currents associated with the same phase-to-phase voltage, interacts withthe polarizing flux to produce operating torque.

The torque at the balance point of the unit can therefore be expressed bythe following equation:

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Torque = 0 El cos (4) - 0) - KE2 (2)where:

E = phase-to-phase voltage (El?).I delta current Ii - 12).0 = angle of maximum torque of the unit.

= power factor angle of fault impedance.K = design constant.

To prove that equation (2) defines a mho characteristic, divide bothsides by E2 and transpose. The equation reduces to:

or:

cos (4) - o) = K

Y cos ( - o) = K (3)

Thus, the unit will pick up at a constant component of admittance at afixed angle depending on the angle of maximum torque. Hence the name mhounit.

ON3 Unit

The schematic connections of the 0M3 unit are similar to those for the N2unit in Figure 4B except that a transactor TR-3 has been added with primarywindings energized by the two line currents. The transactor secondary voltagecan, if desired, be introduced in series with the voltage that energizes theside poles, resulting in a polarizing quantity proportional to E + IZT3, whereZT3 is the transfer impedance of transactor TR-3.

The inclusion of the IZT3 term in the polarizing quantity has the effectof enlarging the rnho characteristic of the 0M3 unit to include a portion ofthe system behind the relay location while retaining the forward reach of theunit. (See section under CHARACTERISTICS - ON3 Unit.)

CHARACTERISTICS

Mi Unit

1. Impedance Characteristic

The impedance characteristic of the M1 unit is shown in Figure 6 forthe 0.75 ohm basic minimum reach setting at a maximum torque angle of600. This characteristic is obtained with the terminal voltage of therelay supplied directly to the restraint circuit of the Mi unit, that is,with the M1 taps on the auto-transformer tap block set at 100%. Thiscircular impedance characteristic can be enlarged, that is, N1 unit reachincreased, by up to 10/i by reducing the percentage of the terminalvoltage supplied to the restraint circuit by means of the N1 taps on theauto-transformer tap block, and the circle can be further enlarged,providing a total range adjustment of up to 40/1, by means of the basicminimum reach tap screws. The circle will always pass through the originand have a diameter along the 600 impedance line equal to the ohmic reachof the unit as expressed by the following equation:

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Ohmic Reach (Input Tap) 7Min (4)M1 Tap Setting (%)

where:Input Tap = Input Tap Setting in percent (normally 100%) except asexplained under “Vernier Adjustment for Low Tap

Settings” in paragraph 7.

ZM-jn = Basic minimum phase-to-neutral ohmic reach of the unitas set by taps).

The angle of maximum torque of the N1 unit can be adjusted up to 75°(see SERVICING) with negligible effect on the reach of the unit.

2. Directional Action

The N1 unit is carefully adjusted to have correct directional actionunder steady-state, low voltage and low current conditions. For faultsin the non-tripping direction, the contacts will remain open at zerovolts between 0 and 60 amperes. For faults in the tripping direction,the unit will close its contacts between the current limits in Table IVfor the three basic minimum—reach settings at the voltage shown:*

TABLE IV

Basic Mm. ** Volts Current Range forReach Tap (Studs 17-18) Correct DirectionalAction

0.75 ohm **4Q V 6 - 60 A1.5 **30 3 - 603.0 2.0 , 1.5 - 60

** The unit is set at the factory on the 1.5 ohm tap for correctdirectional action over the indicated current range. A variation of10% can be expected on the values listed.

Approximate values; adjust control spring if using 0.75 or 3 ohmtap.

For performance during transient low-voltage conditions, where thevoltage was normal at 120 volts prior to the fault, refer to theparagraph below on memory action.

3. Underreach

At reduced voltage the ohmic value at which the M1 unit will operatemay be somewhat lower than the calculated value. This “pullback” orreduction in reach is shown in Figure 7 for the 0.75, 1.5, and 3 ohmbasic minimum reach settings. The unit reach in percent of setting isplotted against the three-phase fault current for three ohmic-reach tapsettings. Note that the fault current scale changes with the basicminimum reach setting. The N1 unit will operate for all points to theright of the curve. The steady-state curves of Figure 7 were determinedby tests performed with no voltage supplied to the relay before the faultwas applied. The dynamic curves were obtained with full rated voltage of120 volts supplied to the relay before the fault was applied.* Revised since last issue 8

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4. Memory Action

The dynamic curves of Figure 7 illustrate the effect of memoryaction in the M1 unit, which maintains the polarizing flux for a fewcycles following the inception of the fault. This memory action isparticularly effective at low voltage levels, where it enables the Miunit to operate for low fault currents. This can be most forcefullyillustrated for a zero voltage fault by referring to Figure 7. A zerovoltage fault will normally be right at the relay bus and therefore, toprotect for this fault, it is imperative that the relay reach 0% of itssetting. Figure 7 shows that the M1 unit, under static conditions, willnot see a fault at 0% of the relay setting, regardless of the tapsetting. However, under dynamic conditions when the memory action iseffective, Figure 7 shows that an M1 unit with a 3 ohm basic minimumreach and 100% tap setting will operate if ‘3p is greater than 1.5amperes.

5. Transient Overreach

The operation of the M1 unit under transient conditions at theinception of a fault is important because the relay is normally connectedso that the M1 contacts will trip a circuit breaker independently of anyother contacts. The impedance characteristic of Figure 6 and the steady—state curves of Figure 7 represent steady-state conditions. If the faultcurrent contains a DC transient, the unit may close its contactsmomentarily even though the impedance being measured is slightly greaterthan the calculated steady-state reach. This overreaching tendency willbe at a maximum when a fault occurs at the one instant in either half—cycle that produces the maximum DC offset of the current wave. Themaximum transient overreach of the Mi unit will not exceed 5% of thesteady-state reach for line angles up to 850.

6. Operating Time

The operating time of the M1 unit is determined by a number offactors such as the basic minimum-reach setting of the unit, fault-current magnitude, ratio of fault impedance to relay reach, and magnitudeof relay voltage prior to the fault. The curves in Figure 8 are for thecondition of rated volts prior to the fault. Time curves are given forfour ratios of fault impedance to relay reach setting. In all cases, theM1 taps were in the 100% position and the angle of maximum torque was setat 60° lag.

7. Vernier Adjustment For Low Tap Settings

The input leads to the tapped auto-transformer are normally set at100%, but for applications on lines with a high secondary line impedance,where the M1 tap leads would be set at a low percentage, the inputconnections can be varied by a vernier method to obtain a closer setting.

For example, if the desired first—zone reach is 4.5 ohms and thebasic minimum reach setting of the M1 unit is 3 ohms, with the inputsetting on 100%, the M1 tap leads would be:

100 (3’ = 66.7%Tap Setting = ‘

4.5

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This desired reach setting can be made within 0.45% accuracy bymeans of the 67% tap. However, if the desired first—zone reach were 28.5ohms, the output tap setting would be:

100 (3) 10.5%28.5

The nearest output tap would be 11%, which is 4.2% off the desiredvalue. To correct this, the input leads can be shifted to 95%, in whichcase, the output would be:

_95 (3)= 10%

28.5

Note that if the input leads are connected to a tap lower than 100%,this lower input percentage also applies in the ohmic reach equations (5)and (6) for the N2 and ON3 units.

CAUTION: DO NOT reduce the input tap setting below the highestof the output or restraint_tap settings,_or below 90L

N2 Unit

1. Impedance Characteristic

The impedance characteristic of the N2 unit is shown in Figure 9 forthe 1 ohm basic minimum reach setting at a maximum torque angle of 600.As with the N1 unit, this circle can be expanded by means of the N2 tapson the auto—transformer tap block, providing a range of up to 10/1, or bychanging the basic minimum reach of the unit by means of the links on therear of the M2 subassembly, providing a total range of up to 30/1. Thecircle will always pass through the origin and have a diameter along the600 impedance line equal to the ohmic reach of the unit as expressed bythe following:

Ohmic Reach = (Input Tap) ZMjn (5)

M2 Tap Setting (%)where: -

ZMin = Basic minimum phase-to-neutral ohmic reach of theunit.

Input Tap = Input Tap Setting in percent (normally 100%) except asexplained under CHARACTERISTICS, M1 unit. Paragraph 7.

The angle of maximum torque of the N2 unit can be adjusted up to 75°(see SERVICING) with resulting increase in reach to approximately 120% ofits reach at 60° for the same tap setting. This is shown by the dottedcharacteristic in Figure 9.

2. Directional Action

The N2 unit is carefully adjusted to have correct directional actionunder steady-state, low voltage and low current conditions. For faultsin the non-tripping direction, its contacts will remain open at zero

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and between 0 and 60 amperes. For faults in the tripping direction, theunit will close its contacts between the current limits in Table V forthe three basic minimum reach settings:

* TABLE V

Basic Minimum ** Volts Current Range forReach Tap (Studs 17-18) Correct Directional

Action

1.0 ohms **40 V 6 - 60 A2.0 **30 3 - 603.0 2.0 2 - 60

** The unit is set at the factory on the 2.0 ohm link setting forcorrect directional action over the indicated current range. Avariation of . 10% can be expected on the values listed.

Approximate values; adjust control spring if using either ohm or 3ohm tap.

Performance during transient low-voltage conditions is covered in alater paragraph on Memory Action.

3. Underreach

The reduction in reach of the M2 unit at reduced voltage is shown inFigure 10 for the 1, 2, and 3 ohm basic minimum reach settings. Thereach in percent of setting is plotted against three-phase fault currentfor three ohmic-reach tap settings. Note that a different fault currentscale is shown for each basic minimum reach setting. The M2 unit willoperate for all points to the right of the curve. The data for thesecurves was taken in the same manner as the M1 curves previouslydescribed.

4. Memory Action

As shown by the dynamic curves of Figure 10, the M2 unit has abuilt-in memory action feature similar to that of the Mi unit previouslydescribed.

5. Transient Overreach

Since the M2 unit is used to trip the circuit breaker through thecontacts of a timing relay, or as the directional unit in a carrier—current relaying scheme, it is not necessary to control the transientoverreach as was done in the M1 unit. The M2 unit will have correctdirectional action during transient conditions.

6. Operating Time

The operating time of the M2 unit is determined by the same factorsdescribed for the Mi unit. The curves in Figure 11 are for the conditionof rated volts prior to the fault. Since the transient overreach is notlimited (see Paragraph 5 above) the M2 unit tends to be faster than theM1 unit.

* Revised since last issue 11

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0M3 Unit

1. Impedance Characteristic

The 0M3 unit is similar to the M2 unit except that a transactor hasbeen included, with primary windings that can be connected in series witheach current operating coil, and a secondary winding connected in serieswith the polarizing circuit. The primary windings are connected to aterminal block so that the windings can be either inserted into orremoved from the current operating circuit by means of links.

When the transactor primary windings are out of the circuit, the 0M3impedance characteristic will be similar to the M2 characteristic exceptthat the factory—set maximum torque angle is 750• This characteristic isrepresented by the solid circle in Figure 12, which shows the 3-ohm basicminimum reach.

When the transactor primary is in the circuit, the transactorsecondary output is added in series with the relay terminal voltage andthe vector sum applied to the polarizing circuit. The effect of this isto enlarge the 0M3 characteristic to include the origin of the R-Xdiagram while retaining the forward reach at its initial value, OA inFigure 12. The resulting characteristic will be offset by approximately0.5 ohm as shown by the dotted circle in the figure.

The forward ohmic reach of the unit along the 75° impedance line, OAin Figure 12, can be increased by means of the 0M3 taps on the auto-transformer tap block, which provide a range of 10/1:

Ohmic Reach (Input Tap) (6)0M3 Tap Setting (%)

where:ZMjn = basic minimum phase-to-neutral ohmic reach of the unit

(3 ohms unless otherwise stamped on nameplate).

Input Tap = input tap setting in percent (normally 100% except aspreviously explained under CHARACTERISTICS, N1 unit,Paragraph 7).

It is important to note that the ohmic reach as determined fromequation (6) is always the distance along the 750 maximum torque linefrom the origin to the intercept with the circle, OA in Figure 12,whether the circle passes through the origin or is offset. Changing theohmic reach over the recommended 10/1 range will have little effect onthe 0.5 ohm offset.

2. Directional Action

The unit has been adjusted so that when it is connected for zerooffset it will have correct directional action under steady-state lowvoltage and low-current conditions. For faults in the non—trippingdirection, its contacts will remain open at zero volts and between 0 and60 amperes. For faults in the tripping direction, the unit will closeits contacts at 4 volts between 1.5 and 60 amperes.

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3. Underreach

The reduction in reach of the 0M3 unit at reduced voltage is shownin Figure 13 for the zero offset setting, and in Figure 14 for 0.5 ohmoffset. Reach in percent of setting is plotted against three—phase faultcurrent. The 0M3 unit will operate for points to the right of the curve.The data for these curves was taken in the same manner as for the M1curves previously described.

4. Memory Action

As shown by the dynamic curve of Figure 13, the 0M3 unit has abuilt-in memory action feature similar to that of the Mi unit previouslydescribed.

5. Transient Overreach

Since the 0M3 unit is applied to trip the circuit breaker throughthe contacts of a timing relay, or as the carrier-start relay in carrier-current relaying schemes, it is not necessary to control the transientoverreach as was done for the M1 unit. When connected for zero offset,the unit will have correct directional action during transientconditions.

6. Operating Time

The operating time curves for the 0M3 unit are shown in Figures 15and 16. All curves in these figures are for the condition of rated voltsprior to the fault with 100% restraint tap setting.

The curves in Figure 15 show the average operating time of the unit,that is, time to close the normally-open contact with the unit connectedfor zero offset. These curves also apply for faults in the forwarddirection if the unit is connected for 0.5 ohm offset.

The curves in Figure 16 shown opening times of the normally-closedcontact, with the unit connected for 0.5 ohm offset, for faults in thedirection of the reach setting (forward) and for faults in the directionof the offset (reverse). It will be noted that for equivalentconditions, that is, for the same operating current and the same ratio offault impedance to reach setting (or offset), the 0M3 unit is faster forfaults in the forward direction. This results from the strong initialmemory action” inherent in the unit, which tends to sustain thepolarizing flux for a few cycles following inception of the fault. Forfaults in the forward direction, this produces a higher operating torqueand hence faster operation.

General

The R-X diagrams in Figures 17 and 18 show overall relay impedancecharacteristics of the CGY51 relay for two typical applications. The diagramin Figure 17 shows a typical arrangement of the Mj, M2 and 0M3 characteristicsfor a step-distance application. The 0M3 unit operating circuit has beenconnected so that the unit has no offset and “looks” in the same direction as

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the M1 and M2 units. This is the scheme illustrated by the typical elementarydiagram in Figure 3. In some cases it may be desirable to introduce the 0.5ohm offset into the foward-looking 0M3 characteristic, a variation that isalso shown in Figure 3.

The diagram in Figure 18 shows the usual arrangement of the N1, M2 andON3 characteristics in a directional—comparison carrier relaying application.This arrangement, with the direction of the ON3 characteristic opposite tothat of the other two units and with the 0.5 ohm offset introduced, is knownas the “reversed 0M3” connection.

Current CircuitsBURDENS

The maximum current burden imposed on each current transformer at 5amperes by a set of three GCY51A relays is listed in Table VI.

TABLE VI

This data is for the 3.0 ohm basic reach tap of the N1 and N2 units. Theburden with the N1 unit in the 1.5 or 0.75 ohm tap, or with the N2 unit in the2 or 1 ohm tap, will be slightly lower.

Potential Circuits

The maximum potential burden imposed on each potential transformer at 120volts by a set of three GCY51A relays is 42.2 VA at 0.99 PF. This total relayburden, as well as the maximum burden imposed by each unit, is listed in Tablevi’.

TABLE VII

The data in Table VII applies when the Mi, M2, and ON3 tap leads and theinput tap are all on 100%. The restraint circuit burdens, and hence the totalrelay burden, will decrease when the tap leads for the three units are set atless than 100% to obtain the desired reach settings.

CIRCUIT R j X P.F. WATTS VA

N1 Restraint 3200 j 0 1.0 4.5 4.5Mi Polarizing 1300 -j 680 0.89 8.7 9.8

M2 Restraint 1150 +j 1370 0.64 5.2 8.1N2 Polarizing 1440 -j 217 0.99 9.7 9.8

0M3 Restraint 1025 +j 1460 0.57 4.6 8.00M3 Polarizing 1540 —j 162 0.99 9.1 9.2

Total Relay 340 +j 46 0.99 41.8 42.2

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The potential burdens at tap settings less than 100% can be calculatedfrom the following formulae.

M1 Unit

VA = (a+jb) M1 Tap Setting (%) + (c-fjd)Input Tap Setting (%)

2 Unit

VA (e+jf) M2 Tap Setting (%)+ (g+jh)

Input Tap Setting (%)

0143 Unit

VA = (k+jm) 0143 Tap Setting (%)+ (n+jp)

Input Tap Setting (%)

The terms (a+jb), (c+jd), etc. represent the burdens of the i, 2 and0M3 potential circuits expressed in Watts and Vars with their taps on 100%.The values of these terms for 60 cycle relays are given in Table VIII.

TABLE VIII

Circuit Term (Watts + j Vars)(Watts + j Vars)

M1 Restraint a + j b 4.5 + j 0Mi Polarizing c + j d 8.7

- j 4.5

2 Restraint e + j f 5.2 + j 6.2

2 Polarizing g + j h 9.7—

j 1.5

0113 Restraint k + ,j m 4.6 + j 6.50143 Polarizing n + j p 9.1

— .j 1.0

Total burden for the relay for specific percent tap settings of the M1 M2,and 0143 units can be obtained by adding the Watts and Vars for each unit asdetermined by the above formulae and converting the total to volt-amperes.

Note that the burden figure in Table VIII for the 0143 polarizing circuit isthe value with zero offset. However, the change introduced when the offset isset at 0.5 ohm will be insignificant.

The input tap setting in the above formulae is normally 100%. In somecases, however, the input tap may be set at some point between 90% and 100%(see “Vernier Adjustment for Low Tap Settings” in the CHARACTERISTICSsection).

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CALCULATION OF SETTINGS

There are six settings that must be made when GCY51A relays are applied forthree-step distance protection. These are:

First zone reach settingSecond zone reach settingThird zone offset settingThird zone reach settingSecond zone time delay settingThird zone time delay setting

The last two settings are made on the associated RPM or SAM timing relay.Table IX and the following discussion provide a qualitative guide for settingthe GCY relays and their associated timer when they are applied in straightdistance schemes.

TABLE IX

UNIT TWO-TERMINAL LINES THREE-TERMINAL LINES

M1 Set for a maximum of 90% Set for a maximum of 90% of theof the line impedance. impedance to the nearest remote

terminal. Do not includethe effects of infeed.

M2 Set for a minimum of 110% With all 3 terminal breakersof the line impedance. closed, calculate the effective

impedance seen by this unit for athree-phase fault at one of theremote terminals. Repeat for afault at the second remoteterminal. Include the effects ofinfeed in both cases. Select thelarger of the two impedances andset this unit for at least 110% othis impedance.

0M3 Since the third zone provides back—up protection for faults onadjacent lines and buses, its reach setting, offset, and directionwill depend on the user’s preferences.

The settings for the second and third zone time delays will depend onwhat these units must coordinate with. A general rule would be to set thetime delay long enough to ensure coordination based on the total clearing timefor the most remote fault that the unit will reach. Thus, if the M2 unit atthe terminal under consideration will reach no further than into first zoneson all the remote lines, the second zone time must be set long enough tocoordinate with remote first zone total clearing times. On the other hand, ifthe M2 unit is set long enough to reach beyond remote first zones, the secondzone time must be set longer than the remote second zone total clearing times.Similar comments would apply to the third zone time delay setting.

Assume that it is desired to use GCY51A relays to protect the twoterminal, 15 mile, 69KV transmission line shown in Figure 19.

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GEI-98338

Maximum load current = 450 amperes

CT Ratio = 600/5 120/1

PT Ratio = 69,000/115 = 600/1

z CT RatioSEC = ZPRIM PT Ratio

ZSEC = 15(0.14 + jO.80) = 0.42 + j2.40 ohms

ZSEC = 2.50 /800 secondary ohms

First Zone Setting

Assume that the impedance of the line section is accurately known so thatthe first zone (M1) unit can be set for 90% of the line length. This wouldrequire a setting that will reach:

0.9 (2.5) /80° 2.25 /80° ohms

The highest basic minimum reach that would accommodate this impedance is1.5 ohms. The restraint tap setting required is obtained from the followingequation:

T (Zmin cos- e) (Input Tap)

ZLwhere:

T = Restraint Tap Setting in percent.ZL = Desired reach in ohms at angle p.

= Angle of Impedance ZL.r = Maximum Torque Angle of Unit.

Zmjn = Basic minimum reach setting of the Unit.Input Tap Input Tap Setting in percent (normally 100%).

In this case:Zmjn = 1.5 ohms.

ZL = 2.25 ohms.= 80°.

Since this is a first zone unit, the maximum torque angle 8 is assumed tobe set at 600. Therefore:

T = 1.5 cos (80—60) (Input Tap)2.25

T = 0.626 (Input Tap)

With the input tap set on 100%, the restraint tap, T, would have to beset at 63%. This would provide a reach setting of 2.24 ohms at 80° ratherthan the 2.25 desired. This is so little difference that it is not worthconsideration. If the difference were significant, restraint tap T would haveto be set on 62% rather than 63%, and the input tap would be reduced to alevel where:

62— X 100 = Percent Input Tap

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GEI-98338

It should be noted that there is only one input tap setting, so this samesetting applies to all three zones. Thus, in this example, the input tap asit appears in the equations for setting the second (M2) and third (0M3) zoneunits will also be 100%.

Second Zone Setting

Assume that after due consideration of the lines fed off the remote busit is desired to set the second zone CM2) unit to reach 5.2 /750 ohms. Assumefurther that because of this setting fault resistance wil1t present anyproblem, so the second zone unit can be set at 750 where it will be lesslikely to operate on system swings. The required second zone (M2) unitrestraint tap setting will be:

T = (Zmin cos ( — 0) (Input Tap)7L

where these terms have the same significance as in the equation for the M1unit setting. In this case:

Zmjn = 3.0 X 1.2 = 3.6 ohms.ZL = 5.2 ohms.

= 750

= 750

Input Tap = 100%.

Note that the basic minimum reach tap (Zmjn) was selected as 3 ohms inthis case because it is the highest tap that will accommodate the desiredreach setting. The factor of 1.2 was used because the minimum reach with a75° maximum torque setting is approximately 120% of the basic reach when theangle of maximum torque is 600.

T 3.6 cos (75 -75) X 1005.2

T = 69.3%.

Set on 69%.

Third Zone Setting

Assume that the desired third zone setting is 8.0 /70° ohms in theforward direction and 0.5 ohm in the reverse (offset) direction. The currentcircuit connections should be checked against the external connection diagramof Figure 3 to be sure that the actual connections are such as to give thelong reach in the desired direction. Also, the offset links should be set inthe “IN” position.

Since the forward reach of this unit is not affected by the offsetsetting, the restraint tap setting in percent is given by the followingequation:

T = (Zmin cos ( - 0)(Input Tap)

ZLwhere these terms have the same significance as in the equation for the Mi andM2 un)t.

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GE 1-98338

In this case:

= 3.0 ohms.= 8.0 ohms.= 70°.

0 750•

Input Tap 100%.

Thus,

T 3.0 cos (70 75) X 1008.0

T = 37.4%.

Set the tap on 37%. If the same forward reach setting was desired withno offset, the same tap setting would apply but the offset links would have tobe set in the “OUT” postion.

Sensitivity Check

The mho units in the GCY5IA have a basic sensitivity that is a functionof the control spring setting. For the control spring settings recommended inthis book, the sensitivities of the three mho units are given in the curves ofFigures 7, 10, 13, and 14. Assume that the minimum three-phase fault currentsflowing in the relays for faults in first, second, and third zones are 12, 5,and 2.5 amperes respectively. For the first zone unit, with a basic minimumreach setting of 1.5 ohms and a restraint tap setting of 63%, Figure 7indicates that the unit will operate for a 12 ampere fault anywhere from therelay location to a point practically 100% of the distance to its set reach.

The performance of the second zone unit, with a basic minimum reachsetting of 3 ohms and a restraint tap setting of 69% can be checked fromFigure 10. By interpolating between the 50% and 100% curves, note that thesecond zone unit will operate at 5 amperes for any fault from approximately 1%to 99% of the reach setting. It should be noted that since the second zoneunit will operate in conjunction with the timer, memory action will not beeffective and the steady-state portion of the curve must be considered. Thus,from the relay location to a point approximately 1% of the set reach, if thefault current is 5 amperes the second zone inho unit will provide no time delayprotection. However, this portion of the line is protected by the first zone(M1) unit, which operates without time delay and hence has effective memoryaction. Also, for a fault in this 1% portion of the line, the current wouldbe on the order of the 12 ampere figure assumed above for a first zone fault.

The performance of the third zone unit, with a basic minimum reach of 3ohms, a restraint tap setting of 37% and 0.5 ohm offset, can be checked fromFigure 14. By interpolating between the 25% and 50% curves, it will be notedthat the third zone unit will operate at the assumed 2.5 ampere fault currentfor any fault with an apparent impedance within 98% of its setting.

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GEI—98338

CONSTRUCTION

The Type GCY51 relays are assembled in the standard large-size, double-end ([2) drawout case having studs at both ends in the rear for externalconnections. The electrical connections between the relay units and the casestuds are made through stationary molded inner and outer blocks, between whichnests a removable connecting plug that completes the circuits. The outerblocks attached to the case have the studs for the external connections, andthe inner blocks have the terminals for the internal connections.

Every circuit in the drawout case has an auxiliary brush, as shown inFigure 20, to provide adequate overlap when the connecting plug is withdrawnor inserted. Some circuits are equipped with shorting bars (see internalconnections in Figure 21), and on those circuits it is especially importantthat the auxiliary brush make contact, as indicated in Figure 20, withadequate pressure to prevent the opening of important interlocking circuits.

The relay mechanism is mounted in a steel framework called the cradle andis a complete unit with all leads terminated at the inner block. This cradleis held firmly in the case with a latch at both top and bottom and by a guidepin at the back of the case. The connecting plug, besides making theelectrical connections between the respective blocks of the cradle and case,also locks the latch in place. The cover, which is drawn to the case bythumbscrews, holds the connecting plugs in place. The target reset mechanismis a part of the cover assembly.

The relay case is suitable for either semi-flush or surface mounting onall panels up to 2 inches thick, and appropriate hardware is available.However, panel thickness must be indicated on the relay order to be sure thatproper hardware will be included.

A separate testing plug can be inserted in place of the connecting plugto test the relay in place on the panel, either from its own source of currentand voltage, or from other sources. Or the relay can be drawn out andreplaced by another that has been tested in the laboratory.

Figures 1 and 2 show the relay removed from its drawout case with allmajor components identified. Symbols used to identify circuit components arethe same as those that appear on the internal connection diagram in Figure 21.

The relay includes three major subassembly elements:

1. The lower element includes the Mi unit with associated circuitcomponents. Adjustable reactor X11, used in setting the angle of maximumtorque, and rheostat R11, used in setting basic minimum reach, can beadjusted from the front of the relay. Transactor TR-1, with tap blockfor selecting the basic minimum reach of M1, is mounted on the rear ofthe element with tap screws accessible from the front.

2. The middle element includes the M2 unit with its associated circuitcomponents. Rheostats R12 for setting basic minimum reach and R22 forsetting angle of maximum torque are accessible from the front of therelay. A terminal block with links for selecting the basic minimum reachis mounted at the rear of the element.

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GE 1—98338

3. The top element includes the 0M3 unit with its associated circuitcomponents. Rheostats R13 for setting minimum reach and R23 for settingthe angle of maximum torque are accessible from the front of the relay.Transactor TR—3 with terminal block for inserting or removing the offsetis mounted on the upper element. The terminal block with the selectionlinks faces the rear. The tapped auto-transformer, which determines thereach of all three units within their selected range, is also mounted onthe upper element, hut the tap block that provides the 1% adjustmentsteps is mounted along the right side of the relay.

With reference to the above paragraphs, it should be noted that

Ru, Xii R12, R22, R13, and R23 are not used in the normal fieldadjustments of the relay, but only if it is determined that a basicfactory setting has been disturbed. (see SERVICING).

RECEIVING, HANDLING, AND STORAGE

These relays, when not included as a part of a control panel, will beshipped in cartons designed to protect them against damage. Immediately uponreceipt of a relay, examine it for any damage sustained in transit. If injuryor damage resulting from rough handling is evident, file a damage claim atonce with the transportation company and promptly notify the nearest GeneralElectrical Sales Office.

Reasonable care should be exercised in unpacking the relay in order thatnone of the parts are injured nor the adjustments disturbed.

If the relays are not be installed immediately, they should be stored intheir original cartons in a place that is free from moisture, dust andmetallic chips. Foreign matter collected on the outside of the case may findits way inside when the cover is removed and cause trouble in the operation ofthe relay.

ACCEPTANCE TESTS

Immediately upon receipt of the relay, an INSPECTION AND ACCEPTANCE TESTshould be made to make sure that no damage has been sustained in shipment andthat the relay calibrations have not been disturbed. If the examination ortest indicates that readjustment is necessary, refer to the section onSERVICING.

Visual Inspection

Check the nameplate stamping to make sure that the model number andrating of the relay agree with the requistion.

Remove the relay from its case and check that there are no broken orcracked molded parts or other signs of physical damage, and that all screwsare tight.

Mechanical Inspection

1. It is recommended that the mechanical adjustments in Table X bechecked.

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GE 1-98338

TABLE X

Check Points Mi Unit M2 Unit 0M3 Unit

Rotating Shaft End Play .010— .015 inch .010— .015 inch .010— .015 inch

Contact Gap .030- .035 inch .018- .022 inch .040- .060 inch

Contact Wipe .003- .005 inch .003-.005 inch .003- .005 inch(N.0. Contacts)

2. There should be no noticeable friction in the rotating structure ofthe units.

3. Make sure control springs are not deformed and spring convolutionsdo not touch each other.

4. With the relay well leveled in its upright position, the contacts ofall 3 units must be open. The moving contacts of the M1 and N2 unitsshould rest against the backstop. The moving contact of the 0M3 unitshould be making contact with the normally-closed contact, with about.003 to .005 inches wipe. V

5. The armature and contacts of the seal—in unit should move freelywhen operated by hand. There should be at least 1/32’ wipe on the seal-in contacts.

6. Check the location of the contact brushes on the cradle and caseblocks against the internal connection diagram for the relay.

Electrical Checks - Mho Units

Before any electrical checks are made on the N1, M2, and 0113 units therelay should be connected as shown in Figure 22 and be allowed to warm up forapproximately 15 minutes with the potential circuit alone (studs 17-18)energized at rated voltage and with the M1, M2, and 0M3 taps set at 100%. Theunits were warmed up prior to factory adjustment and if rechecked when coldwill tend to underreach by 3% or 4%. Accurately calibrated meters are ofcourse essential

It is desirable to check the factory setting and calibrations by means ofthe tests described in the following sections. The mho units were carefullyadjusted at the factory and it is not advisable to disturb these settingsunless the following checks indicate conclusively that the settings have beendisturbed. If readjustrnents are necessary, refer to the section on SERVICINGfor the recommended procedures.

1. Control Spring Adjustment

Be sure that the relay is level in its upright position. Leave therelay connected a shown in Figure 22 and leave the M1, 112 and 0113 tapleads in the 100% position. The Mi unit tap screws and M2 unit linksshould be in the position that provides the basic minimum reach shown inTable XI, and the 0M3 unit links should be set for zero offset.

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GEI—98338

TABLE XI

BASIC MIN. REACH ANGLE METER TEST CONTACTS CLOSEUNIT (-N OHMS) READS VOLTAGE BETWEEN

1.5 3000 2.QV 2.7 — 3.3A

M2 2 3000 2.0 2.0 — 2.5

0M3 3 285° 4 1.26 - 1.54

Use the following procedure in checking each unit. With the currentset at 5 amperes and the voltage across studs 17—18 at 120 volts, set thephase shifter so that the phase angle meter reads the value shown inTable XI for the unit being tested, that is, so current lags voltage byan angle equal to the angle of maximum torque of the unit. Now reducethe voltage to the low test voltage listed in the table for theparticular unit, and reduce the current to about 2 amperes. Graduallyincrease the current until the contacts of the unit just close. Thisshould occur between the limits shown in Table XI for the unit beingchecked.

2. Clutch Adjustment

The M1, M2, and 0M3 units include a high—set clutch between the cupand shaft assembly and the moving contact, to prevent damage during heavyfault conditions. These clutches have been set at the factory to slip atapproxirnatley 40-60 grams applied tangentially at the moving contact.This can best be checked in the field in terms of volt-amperes by thefollowing methods.

* Use the connections of Figure 22 and set the phase shifter so that,at 120 volts and 5 amperes, the phase angle meter reads the value shownin Table XI for the unit to be checked. Disconnect the M1, M2, and 0M3restraint tap leads, short the M1 leads, and set the N1 and N2 units for3 ohm basic minimum reach. With the polarizing voltage at 120V, increasethe current until the clutch just slips. This should occur between 35and 55 amperes for all units.

* The clutch on either unit can be adjusted by inserting a specialflat open—end wrench, underneath the green composition head directlyabove the spool body of the front coils, so that it engages with theflats on the bakelite on the cup shaft. Hold this wrench, and with a5/16” open end wrench loosen or tighten the clutch by turning the nutbelow the spring wind up sprocket. Turn the nut clockwise (top-frontview) to tighten the clutch setting, counterclockwise to loosen it.

3. Ohmic Reach

With the relay still connected as shown in Figure 22, and with theMi, M2, and OM3 tap leads still in the 100% position, set the phaseshifter so that the phase angle meter reads the angle shown in Table XIIfor the unit to be checked (i.e., current leads voltage by the angleshown, at 5A and 120V). Now reduce the voltage to the value shown inTable XII and increase the current gradually until the normally—open

* Revised since last issue 23

GEI—98338

contacts of the unit just close. This should occur within the limitsshown in Table XII. Note that for the M1 and M2 units the tap screws orlinks should be in the position that gives the basic minimum reach shownin the table.

TABLE XII

(p-ANGLE BASIC MIN. REACH V17_18 PICKUP EQUIV. TEST REACIUNIT METER READS ((p-N OHMS) SET AT AMPS ((p-< OHMS)

3000 1.5 45V 1.46-1.54 3

M2 3000 2 60 1.46-1.54 4

0M3 285° 3 90 1.46-1.54 6

Note that for the test conditions, the mho units see a phase-to-phase fault of twice the basic minimum reach.

The relays are normally shipped from the factory with the basicminimum reach adjustment taps of the M1 and M2 units in the intermediatesetting, that is, 1.5 ohms for Mi and 2 ohms for M2. If the units areset on either of the remaining basic minimum reach taps, 0.75 or 3.0 ohmsfor N1, 1.0 or 3.0 ohms for M2, the basic reach of the units will bewithin ± 4% of the tap plate marking.

4. Angle of Maximum Torque

For the angle of maximum torque check, the connections of Figure 22will be used with the Ml, N2, and ON3 tap leads still in the 100%position, and with the voltage set at the value shown in Table XIII forthe unit to be tested. Pickup of the unit should then be checked withthe current displaced 30° from the maximum torque position in both thelead and lag direction.

TABLE XIII

-ANGLE METER READING

ANGLE OF TEST V1718 PICKUPUNIT MAXIMUM TORQUE ANGLES SET AT AMPS

Mi 300° 3300_2700 45V 16.5-18.2

M2 3000 3300..2700 60 16.5-18.2

0M3 285° 315°-255° 90 16.5-18.2

In checking the M1 unit, the following procedure would be used.First, set the phase shifter so that the phase angle meter reads 3000.Note that while the phase angle is being set, the current should be at Samperes and the voltage on studs 17-18 should be increased temporarily to120 volts. With voltage again at the value shown in Table XIII, increasethe current slowly until the N1 unit picks up. The pickup current shouldbe within the limits shown in the table. Now reset the phase angle at270° and again check the current required to pick up the N1 unit. Thisshould fall within the same limits as for the 33fl0 check.

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GE 1-98338

Note that the two angles used in the previous check, i.e. 33Q0 and2700, are 300 away from the angle of maximum torque. An examination ofthe rnho unit impedance characteristic in Figure 6 shows that the ohmicreach of the unit should be the same at both 330° and 270° and should be0.866 times the reach at the angle of maximum torque.

The angle of maximum torque of the M2 and 0M3 units can be checkedin a similar manner. The 0113 unit should be set for zero offset whilethe angle of maximum torque is being checked.

Electrical Tests - Target Seal-In

The target seal—in unit has an operating coil tapped at 0.6 or 2.0amperes. The relay is shipped from the factory with the tap screw in the 0.6ampere position. The operating point of the seal—in unit can be checked byconnecting from a DC source (4-) to stud 11 of the relay and from stud 1through an adjustable resistor and ammeter back to (—). Connect a jumper fromstud 15 to stud 1 also, so that the seal—in contact will protect the Mi unitcontact. Then close the M1 contact by hand and increase the DC current untilthe seal-in unit operates. It should pick up at tap value or slightly lower.Do not attempt to interrupt the DC current by means of the M1 contact.

INSTALLATION PROCEDURE

Location

The location of the relay should be clean and dry, free from dust,excessive heat and vibration, and should be well lighted to facilitateinspection and testing.

Mounting

The relay should be mounted on a vertical surface. The outline and paneldrilling dimensions are shown in Figure 29.

Connections

The internal connections of the GCY51A relay are shown in Figure 21. Anelementary diagram of typical external connections is shown in Figure 3.

Note on the internal connection diagram (Figure 21) that the mho unitrestraint circuits are connected to terminals 17—18, and the polarizingcircuits to 19-20, with internal jumper leads between 17—19 and 18-20. Onsome installations it may be desirable to separate the restraint andpolarizing circuits, either because of application considerations or toachieve better accuracy in testing. This can be accomplished by removing theinternal jumpers and making the necessary external connections to 17—18 and19-20.

Visual Inspection

Remove the relay from its case and check that there are no broken orcracked component parts and that all screws are tight.

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GEI-98338

Mechanical Inspection

Recheck the Six adjustments mentioned under Mechanical Inspection in thesection on ACCEPTANCE TESTS.

Portable Test Eguprnent

To eliminate the errors that may result from instrument inaccuracies, and

to permit testing the mho units from a single-phase A-C test source, the test

circuit shown in schematic form in Figure 23 is recommended. In this figure

R5 + jX is the source impedance, SF 5 the fault switch, and RL + jXL is theimpedance of the line section for which the relay is being tested. The

autotransformer, TA, which is across the fault switch and line impedance, istapped in 10% and 1% steps so that the line impedance RL + jX may be made toappear to the relay very similar to the actual line on which the relay is tobe used. This is necessary since it is not feasible to provide the portable

test reactor, XL, and the test resistor with enough taps to permit matchingevery possible line.

For convenience in field testing, the fault switch and tappedautotransformer of Figure 23 have been arranged in a portable test box, Cat.No. 102L201, which is particularly adapted for testing directional anddistance relays. The box is provided with terminals to which the relaycurrent and potential circuits as well as the line and source impedances maybe readily connected. For a complete description of the test box, the user isreferred to GEI—38971.

Electrical Tests on the Mho Units

The manner in which reach settings are made for the mho units is brieflydiscussed in the CALCULATION OF SETTINGS section. Examples of calculationsfor typical settings are given in that section. It is the purpose of theelectrical tests in this section to check the ohmic pickup of the M1, M2 andGM3 units at the settings that have been made for a particular line section.

To check the calibration of the mho units, it is suggested that the

portable test box, Cat. No. 102L201; portable test reactor, Cat. No. 6054975;and test resistor, Cat. No. 6158546 be arranged with Type XLA test plugsaccording to Figure 24. These connections of the test box and other equipmentare similar to the schematic connections shown in Figure 23, except that theType XLA test plug connections are now included.

Use of the source impedance, RS + jXS, simulating the conditions thatwould be encountered in practice, is necessary only if the relay is to betested for overreach or contact coordination, tests that are not normallyconsidered necessary at the time of installation or during periodic testing.Some impedance will usually be necessary in the source connection to limitcurrent in the fault circuit to a reasonable value, expecially when a unitwith short-reach setting is to be checked, and it is suggested that a reactorof suitable value be used for this purpose since this will tend to limitharmonics in the fault current.

Since the reactance of the test reactor may be very accurately determinedfrom its calibration curve, it is desirable to check mho unit pickup with thefault reactor alone, due account being taken of the angular difference between

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GEI-98338

the line reactance, XL, and mho unit angle of maximum reach. The linereactance (XL) selected should be the test reactor tap nearest above twice themho unit phase—to—neutral reach, with account being taken of the difference inangle of the test reactor tap impedance and the unit angle of maximum reach.

Explanation of the “twice” factor is as follows: The relay as normallyconnected (V1_2 potential and 11-12 current) measures positive sequence phase-to-neutral impedance. For a phase-to-phase fault, the fault current is forcedby the phase-to-phase voltage through the impedance of each of the involvedphases. In the test circuit the line impedance, ZL, is in effect the sum ofthe impedance of each of the phase conductors and must be so arranged in orderto be equivalent to the actual fault condition. Since the impedance of eachphase must be used to make up the line impedance in the test circuit, itsvalue will be twice that of the phase—to—neutral mho unit reach.

From Figure 25 it is seen that twice the unit reach (i.e. 2Z relay) atthe angle of the test reactor impedance is:

2ZRelay2 ZMin cos (-e) (7)M Tap

where:Zmjn = Basic minimum reach of M1, M2, or ON3 unit.

$ Angle of test reactor impedance.O = Mho Unit Angle of maximum reach.

N Tap = Tap Setting of N1, N2, or ON3.

The test—box autotransformer percent tap for nominal mho unit pickup isthen given by the equation:

% Tap = 2ZRelay (100)

ZL

NOTE: Before proceding with the checks of the Mi, N2 and ON3operating points the relay should be allowed to warm up for about 15minutes with potential circuit alone (studs 17—18) energized atrated voltage and with tap leads all set for 100%. Then change thetap leads to the percent settings determined for the application,and proceed at once with the tests.

Example of N1 Test

As an illustration of the above, the example in the section onCALCULATION OF SETTINGS will be used. In this example the desired reach ofthe Mi unit was 2.25 ohms at the line angle of 800. To obtain this reach itwas calculated that the N1 unit basic minimum reach should be 1.5 ohms,determined by the setting of the two tap screws in the tap block on the frontof the lower unit, and that the N1 restraint tap leads should be in the 63%position. This is accomplished by connecting the lower M1 tap lead to the 60%position and the upper M1 tap lead to the 3% position. The angle of rnaxiniurntorque was 600, which is the normal factory setting.

In determining the test reactor tap setting to use in checking this M15etting, it can oe assLimed as an approximation that the angle, , of the testreactor impedance is 800. Based on this assumption, twice the reach of the M1unit at the assumed angle of the test reactor will be:

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2ZRelay = 2 1.5 X 100 cos (8060) (8)63

= 4.48 ohms

Therefore, the 6-ohm tap of the test reactor should be used. Twice therelay reach at the angle of test reactor impedance should be recalculated,using the actual angle of the reactor tap impedance rather than the assumed80°. Table XIV shows the angles for each of the reactor taps.

TABLE XIV

TAP ANGLE COS (p-60)

24 88 0.88312 87 0.891

6 86 0.8993 85 0.9062 83 0.9211 81 0.934

0.5 78 0.951

From the table it is seen that the angle of the impedance of the 6 ohmtap is 86°. Therefore, twice the M1 unit reach at the actual angle of thetest reactor is:

2ZRelay= 2 1.5 X 100 cos (86-60) (9)

63

= 4.29 ohms

The calibration curve for the particular portable test reactor in useshould be referred to, in order to determine exact reactance of the 6 ohm tapat the current level being used. For the purpose of this illustration, assumethat the reactance is 6.15 ohms. Since the angle of the impedance of the 6ohm tap is 86°, the impedance of this tap may be calculated as follows:

ZL XL / cos 4= 6.15

.9976

= 6.18 ohms

From this calculation it is seen that the reactance and the impedance maybe assumed to be the same for this particular reactor tap. Actually, thedifference need only be taken into account on the reactor 3, 2, 1, and 0.5 ohmtaps.

The test-box autotransformer tap setting that is required to close themho unit contact with the fault switch closed can now be determined asfollows:

% Tap = 4.29(100) = 69.4%

6.18

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GE 1-98338

Thus theorectically the Mi unit contact should remain open with a test-

box tap setting of 70%, and close at 69%. This of course assumes that twice

the M1 unit reach at the test reactor angle is exactly 4.29 ohms. At the L5

ohm basic minimum reach setting the Ml unit reach should check within ± 3% of

the value indicated by the tap setting. So if the close-open points fall

within a range of 67% to 72% test box tap setting, the N1 unit is within

factory tolerance. Note that if the 0.75 or 3 ohm basic minimum reach setting

were used, the N1 unit reach should check within .± 4%.

Although the Ml unit reach is within factory tolerance, it may be

desirable to obtain an operating point closer to the calculated reach as

indicated by the above equation. This can be accomplished by changing the

upper M1 tap lead in 1% steps until the unit operates at the test box percent

tap indicated in the above equation. If the Mi operating point is outside

factory tolerance, refer to the section on SERVICING.

If the ohmic pickup of the Mi unit checks correctly according to the

above, the chances are that the angle of the chdracteristic is correct. The

angle may, however, be very easily checked by using the calibrated test

resistor in combination with various reactor taps. The calibrated test

resistor taps are pre—set in such a manner that when used with 12 and 6 ohm

taps of the specified test reactor, impedance at 600 and 30° respectively will

be available for checking the mho-unit ohmic reach at the 600 and 300

positions. The mho unit ohmic reach at the 0° position may be checked by

using the calibrated test resistor alone as the line impedance. The

calibrated test resistor is supplied with a data sheet that gives the exact

impedance and angle for each of the combinations available. The test—box

autotransformer percent tap for pickup at a particular angle is given by:

% Tap2 (1.5) cos (04)

(100) (10)

(M Tap %) ZLwhere:

0 = Angle of maximum torque of niho unit (60° in example).

Angle of test impedance ZL.

7L = The 600, 300, or 00 impedance value from calibrated

test resistor data sheet.N = Mho Unit restraint tap setting.

As in the previous tests, the source impedance should be readjusted in

each instance to maintain approximately the same fault current level for each

check point.

When checking the angle of maximum reach of the N1 unit as indicated

above, there are two factors to keep in mind that affect the acuracy of the

results. First, when checking the unit at angles of more than 30° off the

maximum reach position, the error becomes relatively large with phase angle

error. This is apparent from Figure 25 where it is seen, for example at the

00 position, that a 20 or 30 error in phase angle will cause a considerable

apparent error in reach. Secondly, the effect of the control spring should be

considered since the mho unit can only have a perfectly circular

characteristic when the control spring torque is negligible. For any normal

level of polarizing voltages, the control spring may be neglected, but in

29

GEI-98338

testing the unit as indicated above it may be necessary to reduce the test-boxautotransformer tap setting to a point where the voltage supplied to the unitmay be relatively low. This reduces the torque level since the polarizing aswell as the restraint voltage will be low, with the result that the controlspring torque will no longer be negligible and the reach of the Mi unit willbe somewhat reduced.

The internal connections of the GCY51 relays (see Figure 21) are arrangedso that the inaccuracies introducted by low polarizing voltage under testconditions can be avoided. This can be accomplished by removing the internaljumpers between terminals 17-19 and 18-20, and making these jumper connectionsexternally for the test. The restraint and polarizing circuits can then beenergized separately as shown by the optional test connections if Figures 23and 24. Be sure to restore the internal jumpers after the test is completed,unless the restraint and polarizing circuits are to be supplied separately onthe installation.

In order to see the effect of the errors mentioned above in their trueproportion it is suggested that the reach characteristic, determined by test,be plotted on an R-X impedance diagram as typified by Figure 6. It is obviousthat the apparent errors in reach, resulting from phase angle error at angleswell off the maximum reach position, occur in a region where the faultimpedance vector will not lie.

M2 Tests

The reach setting and angle of maximum torque of the M2 unit can bechecked in the same manner as the N1 unit, using the connections of Figure 24and the explanation in the preceding sections. When using equations (7), (8),and (9) in determining twice the N2 unit reach at the test reactor angle, andequation (10) in determining the test—box percent tap setting, be sure to usethe proper value of the M2 unit basic minimum reach, as selected by the linksettings on the rear of the middle element. If the 2 ohm basic minimum reachsetting is used, with angle of maximum torque at 60°, the operating point ofthe unit should be within 3% of the calculated test—box setting. If the 1ohm or 3 ohm basic minimum reach setting is used, a ± 4% tolerance can beexpected.

The links used in selecting the basic minimum reach of the M2 unit (seeFigure 2 and the internal connections, Figure 21) are on a two-sectionterminal block on the rear of the middle unit. Each section includes twolinks, labeled A and B, that determine the tap setting of the two currentcoils of the M2 unit. Table XV shows the link settings for the 1, 2, or 3 ohmbasic minimum reach. Both sets of links should always be set in the samepost ion.

TABLE XV

BASIC MIN. REACH A LINKS B LINKS(4-N OHMS) TO TO

1.0 1 02.0 0 23.0 1 2

30

GEI-98338

In the example in the CALCULATION OF SETTINGS section, the M2 angle ofmaximum torque was set at 75°. Therefore, in equations (8), (9), and (10) theangle 0 will be 75°. At this angle the basic minimum reach will be

approximately 1.2 times the reach at the 600 angle of maximum torque. (seeTable II in the section of RATINGS). This figure should be used as Zmin inequations (8), (9), or (10). The operating point with the 75° setting should

be within ± 6% of the calculated test box setting.

j3je st S

The forward reach and angle of maximum torque of the 0M3 unit can bechecked by means of the connections in Figure 24, following the explanationand equations in the preceding paragraphs covering the M1 unit tests. Notethat the angle of maximum torque (8) is 75° and the basic minimum reach (Zmjn)is 3 ohms when using equations (7), (8), (9), and (10). Note that the forwardreach, measured from the origin on the R-X diagram, will be the same whetheror not the unit is connected for offset. (See section on CHARACTERISTICS0M3 Unit, and Figure 12).

If the unit is to be applied with offset it can be checked as follows,using Type XLA test plugs and the connections if Figure 26. With thepotential circuit deenergized and shorted, increase the current slowly in the0M3 operating circuit until the left hand contact just closes. This shouldoccur between 1.5 and 2 amperes for the 100% restraint setting (see Figure14).

Electrical Tests Seal—in Unit

Check that the target seal-in unit is operating at tap value. This canbe done by arranging a series circuit from +125 VDC to stud 11 of the relay,and from stud 1 through a loading resistor that will draw a DC currentapproximately equal to the target seal-in tap setting, and from the loadingresistor back to negative. If the H1 unit contact is closed by hand, thetarget seal-in unit should operate. As a precautionary measure a jumpershould be connected between studs 1 and 26 so that the seal—in contacts willprotect the M1 contact.

If it is necessary to change the tap setting of the target seal-in unitfrom 0.6 to 2 amps, or vice-versa, observe the following procedure. Assumingthe tap is being changed for 0.6 to 2A, remove one of the screws from theleft-hand contact strip and insert it into the 2A position in the right-handstrip, being sure that it is securely tightened. Then remove the screw fromthe 0.6A position and insert it in the vacant hole in the left-hand strip.This procedure ensures that the contact adjustment of the unit will not bedisturbed while the tap setting is being changed.

Overall Tests

An overall check of current transformer polarities, and connections tothe relay, can be made on the complete installation by means of the testconnections and tabulation in Figure 27. A check of the phase angle meterreadings shown in the table for power factor angle and phase sequence involvedwill indicate whether the relay is receiving the correct voltage and currentsfor the conventional connections shown in Figure 3.

31

GEI—98338

Remove the lower test plug from the relay, disconnecting the currentcircuits, and replace the upper test plug with the connection plug. The Mi,M2, and 0M3 (if connected for forward reach) units should develop strongtorque to the right with normal voltage on the relay. Now insert the lowerplug and open the Mi, M2, and 0M3 taps on the main tap block. If thedirection of power and reactive flow is away from the bus and into theprotected line section, the Mi, N2 and 0M3 (if connected for forward reach)units should operate. If the reactive power flow is into the station bus, theresulting phase angle may be such that the units will not operate.

PERIODIC CHECKS AND ROUTINE MAINTENANCE

In view of the vital role of protective relays in the operation of apower system it is important that a periodic test program be followed. It isrecognized that the interval between periodic checks will vary depending uponenvironment, type of relay, and the user’s experience with periodic testing.Until the user has accumulated enough experience to select the test intervalbest suited to his individual requirements, it is suggested that the pointslisted under INSTALLATION PROCEDURE be checked at an interval of from one totwo years.

Contact Cleaning

For cleaning fine silver contacts, a flexible burnishing tool should beused. This consists of a flexible strip of metal with an etched-roughenedsurface resembling in effect a superfine file. The polishing action is sodelicate that no scratches are left, yet it will clean off any corrosionthoroughly and rapidly. Its flexibility ensures the cleaning of the actualpoints of contact. Do not use knives, files, abrasive paper or cloth of anykind to clean relay contacts.

SERVICING

If it is found during installation or periodic tests that Mi, N2, or 0M3unit calibrations are out of limits, they should be recalibrated as outlinedin the following paragraphs. It is suggested that these calibrations be madein the laboratory. The circuit components listed below, which are normallyconsidered to be factory adjustments, are used in recalibrating the units.These parts may be physically located from Figures 1 and 2. Their locationsin the relay circuit are shown in the internal connection diagram of Figure21.

R11 — N1 unit reach adjustmentX11 — M unit phase angle adjustment

— N2 unit reach adjustmentR22 — N2 unit phase angle adjustmentR13 - 0M3 unit reach adjustmentR23 — ON3 unit phase angle adjustment

NOTE: Before making pickup or phase angle adjustments on the mhounits, the unit should be allowed to heat up for approximately 15minutes energized with rated voltage alone and with the restrainttap leads (N1, N2, and ON3) set for 100%. Also it is important thatthe relay be mounted in an upright position so that the units arelevel.

32

GE 1-98338

Control Spring Adjustments

Make connections to the relay as shown in Figure 22 and set the tap leads

for the unit to be adjusted (M1, M2, and 0M3) on 100%. The N1 tap screws and

M2 links should be in the position for the basic minimum reach shown in Table

XVI and the 0M3 unit should be set for zero offset. Make sure that the relay

is in an upright position so the units are level. With the current set at 5

amperes and the voltage across studs 17—18 at 120 volts, set the phase shifter

so that the phase angle meter reads the value shown in Table XVI for the unit

being tested.

TABLE XVI

BASIC MIN. REACH ANGLE METER TEST SET VALUE OF

UNIT ((p-N OHMS) READS VOLTAGE CURRENT

M1 1.5 3000 1.5 2.75

N2 2 300° 1.5 2.5

0M3 3 285° 4 1.4

Now reduce the voltage to the test voltage value and set the current at

the value shown in Table XVI for the unit being adjusted. Insert the blade ofa thin screwdriver into one of the slots in the edge of the spring—adjusting

ring (see Figure 28) and turn the ring until the contacts of the unit justclose. If the contacts were closing below the set point shown in Table XVI,

the adjusting ring should be turned to the right. If they were closing abovethe set point, the adjusting ring should be turned to the left.

Ohmic Reach Adjustment

The basic minimum reach of the M1 N2, or ON3 units can be adjusted by

means of rheostats that are accessible from the front of the relay. Connect

the relay as shown in Figure 22, leave the Mi N2, and ON3 tap leads at 100%,

and be sure that the basic minimum reach taps for M1 and M2 are in the

position shown in Table XVII. With current at 5 amperes and voltage at 120V,

set the phase shifter so that the phase angle meter reads the angle shown in

the table for the unit to be checked. Now reduce the voltage on studs 17-18

to the set value shown in Table XVII and adjust the appropriate rheostat so

that the unit picks up at 15 amperes within ± 2%.

TABLE XVII

BASICMIN. REACH p ANGLE METER V17_18 PICKUP ADJUST-

UNIT ((p-N OHMS) READS SET AT AMPS MENT

N1 1.5 3000 45V 15 R11

-N2 2 300° 60 15 R12

GM3 3 285° 90 15

33

GEI—98338

Angle of Maximum Torque

The angle of maximum torque of the mho units can be adjusted by means ofa reactor (Mi) or rheostats (M2 and 0M3) accessible from the front of therelay. Use the connections in Figure 22, leave the Mi, M2, and 0M3 tap leadsat 100%, and be sure that the basic minimum reach selection taps for Mi and M2are in the position shown in Table XVIII.

TABLE XVIII

BASIC MIN. p-ANGLE METER READINGSREACH ANGLE OF TEST V17_18 PICKUP

UNIT (-N OHMS) MAX. TORQUE ANGLES SET AT AMPS ADJUSTMENT

L__N1 1.5_- 3000 3300 & 270° 45V 17.3 Xli

M2 2 3000 3300 & 2700 60 17.3 R22

0M3 3 285° 315° & 255° 90 17.3 R23

The procedure used in setting the angle of maximum torque is to adjustthe reactor (N1) or rheostat (M2 and O4) so that the pickup amperes, at aspecified set voltage on studs T7-18, wfll be the same at angles leading andlagging the maximum torque angle by 300. The test angles, set voltages, andpickup amperes are shown in Table XVIII. For example if the M1 unit is to beadjusted the following procedure would be used. First, the reach of the unitat its angle of maximum torque should be checked and adjusted if necessary asdescribed in Ohmic Reach Adjustment in this section and Table XVII. Next setthe phase shifter so that the phase angle meter reads 3300 (Note that phaseangle adjustments should be made at 120 volts and 5 amperes). Then set V17_18at 45 volts and adjust X11 so that the M1 unit closes its contacts at 17.3amperes 2%. The pickup should then be checked at 2700 with the same setvoltage and should be 17.3 amperes .± 2%. Refine the adjustments of X11 untilthe pickup is within limits at both 2700 and 3300.

Note that an adjustment of the angle of maximum torque will have asecondary effect on the reach of the unit, and vice-versa. Therefore, to besure of accurate settings it is necessary to recheck the reach of a unitwhenever its angle of maximum torque setting is changed, and to continue a“cross” adjustment routine of reach and angle of maximum torque until both arewithin the limits specified above.

As noted in Table II under the section on RATINGS, the angle of maximumtorque of the N1 and M2 units can be adjusted up to 75°, if desired. If thischange is made, the reach of the Mi unit will increase only slightly, but theM2 unit reach will increase to about 1.2 times its value at the 600 angle. Tomake this adjustment, refer to Table XIX and proceed as follows:

34

GEI-98338

TABLE XIX

BASIC MIN. -ANGLE METER READINGSREACH AT 750 ANGLE OF TEST V17_18 PICKUP

UNIT (-N OHMS) MAX. TORQUE ANGLES SET AT AMPS ADIJUSTMENT

N1 1.5 285° 315° & 255° 45V 17.3 X11

2.4 285° 315° & 255° 60 14.4 R22

Since the values in Table XIX for basic minimum reach at 75° will not beexact unless refinements in the reach adjustment are made, a tolerance of .± 4%

should be allowed when checking pickup amperes at the 3Q0 leading and laggingpositions.

For example, if the N2 unit is to be reset for a 750 angle of maximum torque,

set the phase shifter so the phase angle meter reads 315°. Then with V17_18

at 60 volts, adjust R22 until the unit picks up at 14.4 amperes ± 4%. Thenreset the phase shifter for a 2550 phase angle meter reading and check that

the pickup amperes are within the same limits.

If desired, the reach at 75° can now be checked by setting the phaseshifter so the phase angle meter reads 285° and checking pickup current with

60 volts on studs 17-18. The unit should pick up between 11.5 and 13.5

amperes. If desired, the reach adjustment CR12) can be refined to obtain a

pickup current closer to the 12.5 ampere nominal value. If this is done, the750 angle of maximum torque should be rechecked.

RENEWAI PARTS

It is recommended that sufficient quantities of renewal parts be carried

in stock to enable the prompt replacement of any that are worn, broken, or

damaged.

When ordering renewal parts, address the nearest Sales Office of the

General Electric Company, specify quantity required, give the name of the partwanted, and complete nameplate data. If possible, give the General Electric

requisition number on which the relay was furnished.

35

GEI—98338

Fig. 1 (8035286) Type GCY51A relay removed from case (front view)Fig. 2 (8035293) Type GCY51A relay removed from case (rear view)Fig. 3 (011689303) Typical external connection diagram showing three—step

distance protection of a transmission line using threeGCY51A relays and one RPM timer

Fig. 4 (011686891—1) Schematic connections of the M1, M2, and 0M3 units inthe GCY51A relay

Fig. 5 (0178A8170) Graphical representation of M1 unit operating principleFig. 6 (0178A8171) Minimum steady-state operating characteristic of M1 unitFig. 7 (0178A8172) Steady-state and dynamic reach curves for the M1 unit of

the GCY51A relayFig. 8 (01]8A8173) Operating time curves for the M1 unit in the GCY51A

relayFig. 9 (0178A8174) Minimum steady—state operating characteristic of M2 unitFig. 10 (0178A8175) Steady-state and dynamic reach curves for the M2 unit of

the GCY5IA relayFig. 11 (0178A8176) Operating time curves for the M2 unit in the GCY51A

relayFig. 12 (0178A8177) Minimum steady-state operating characteristics of the

0M3 unitFig. 13 (0178A8178) Steady-state and dynamic reach curves for the 0M3 unit

with offset at zeroFig. 14 (0178A8179-1) Steady-state reach curves for the 0M3 unit with offset

at 0.5 ohmFig. 15 (0178A8180) Operating time curves for the 0M3 unit with zero offset

showing time to close normally-open contactFig. 16 (0178A8181) Operating time curves for the 0M3 unit with 0.5 ohm

offset showing time to open the normally-closed contactFig. 17 (0178A8182) Impedance characteristics of Mj., M2, and OM3 units for a

typical step distance applicationFig. 18 (0178A8183) Impedance characteristics of N1, M2, and GM3 units for a

typical directional comparison pilot relayingapplication

Fig. 19 (0178A7169—1) Schematic diagram of typical two-terminal lineFig. 20 (8025039) Cross section of case and cradle block showing auxiliary

brush and shorting barFig. 21 (0178A7049-3) Internal connections (front view) of type GCY5IA relayFig. 22 (0178A8184) Test circuit for the type GCY51A relay using a phase

shifter.Fig. 23 (0178A8185) Schematic diagram of GCY test circuitFig. 24 (0178A8186) Connections for field testing of the type GCY51A relay

using type XLA test plugsFig. 25 (0178A8187) Reach of mho unit Mi, M2, or 0M3 at the angle of the

test reactorFig. 26 (0178A8188) Connections for checking offset of the ON3 unitFig. 27 (0178A8189) Test connections for overall test of type GCY51A relaysFig. 28 (8034958) Four pole induction cylinder unit typifying construction

of the Mi, M2, and 0M3 units in the GCY51A relayFig. 29 (6209276-1) Outline and panel drilling dimensions for type GCY51A

relay

36

DM3 CU1SUN KS

BASIC M NIMH’

RI 4CH SLRI[ID

Mi UNIT

Figure 1 (8035286) Type GCY51A relayremoved from case (front view)

GEI-98338

Figure 2 (8035293) Type GCY51A relayremoved from case (rear view)

Figure 3 (0116B9303-2) Typical external connection diagram showing three-step

distance protection of a transmission line using three GCV51A relays and one RPM timer

(more)37

IAPIl 1)I PAI.I BMI B

1krrA, Q I I

ITAkACCP

AR TC(. • JOB

Ml “DM3‘IN I 41 II

‘TIN;

BASIl M 1,.HJMRI ACH TABMI UNIT

RIDLI III

I-j.

L - - J

BLTENlL ,L

r

D94 SI1 T 1±ci.

94

4 T —

Alit<11J:. Si

r —i IF SIFDN DNLYDN’ JFR J.JAr 55[TASUTMi 15TJli,

TO ID I JiJ’-’ A ID LIIBS TLILIM T4FIC E,A 1; TC TBB ITO I:4fF5 LD!IDTICiS -iBI is 2_EIBTE •1

ii I 41455CT151 I TO A ITT B ID B. ‘ RITIIFIRN; AE USI TO TTII ITO DAID, 3SF TLI!I-lI3TF CTIICTIiI .2,

TIlTLI J

I KR ‘

L ..

GEI-98338

T AJ

H

F t

______ _ __

HUtD

_____

-- —--

_______-______

_1?

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;z-r’ —________

Lu__S A’- --‘— LI 2—1’

-1---L.Y -_F;--LY--- ç—”---.A

?1- 3 :1—1—2

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cN —C P P rpiI1 DuLl ci Lu iC1.€ CI ruC

21)23 LAO AN1) A1D 11) ALL TlO-L[ 1)1)L)% IF Lu,ICI :1

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1YPE O D1)SCIIFT)ON lilT. COhN. FIJTLINe

GCY21A ). 1027141). 0—6209221-

i4i1fl 1) 1- 01217292 i—6211)271

_‘ 31C — K—k,J,%726 6—6209272

062122 [O143 6—6209272

IPO .2)DTIItO(1Q2121’,—jJ 1230.[ 21)26-4

F1 1) RcrIFl[1)1p212l2c,—4I 1041)00134

Figure 3 (continued) (011689303-2) Typical external connection diagram showing three-step

distance protection of a transmission line using three GCY51A relays and one RPM timer

1)1 5Cj0: 2.1—1—2

10 oF 101

CFSET

r --

I COlE

- [ -

-

1111

-

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1262 2

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TJ Tl9l5-

P.-: -1.1 111.11 Ts;:’ ID 21236

7— ()i\( 1)1.11%) tc;oL: D- 060-0— 01 -IXL)Ws 17 1191,

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51261 1772 2F’C’lF

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a ‘(A141)I’ 014 AL Oil - 11)1) 21l1-)hG [2’

38

GEI-98338

BM2 (OR OIq3) UNIT

(TOl- VIEW(

Figure 4 (0116B6891-1) Schematic connections of the Ml, M2, nd O43 units inthe GCY51A relay

AUNIT

(TOP VIF)

1 12

39

GE 1—98338

Figure 5 (0178A8170) Graphicalrepresentation of Mi unit operating

principle

3.

Figure 7 (0178A8172) Steady—state anddynamic reach curves for the M1 unit of

the GCY51A relay

Figure 6 (0178A8111) Minimum steady-state operating characteristic of Mi unit

f:: ff1:L4jL4:4tEii:ct i

______

L ..1..‘

• TM IIéPIDAXL . “..‘ it:,1 :: 4C I.fl*Cf MGL!fl° LAG Tyllal

jFJ, TT&1AGI Walt Fiat= 11GM, 4• T 3 IlC clsl lt .

IGk’lftT tAcit QhllttlT II 2. ltRc&ri,a,eya; 1..

—

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_________

- tM’

LSSL.I_I

_______

—

c44 —— —,

r*f t 3%ij4.’!lr4iGSt_r. iflt444iti

flr.: .w.__,j tr

Figure 8 (0178A8173) Operating timecurves for the Mi unit in the GCY51A

relay

.8

.7

p‘‘‘ /, ‘, f. U ThU I IT

-

‘I h “I .3 I.’

.1:31.1:1 I. .‘a:I.(‘Ii I• 1.-I

—

—

‘4.

600 SETTING0.75 0FIli&S

p

I Ac 12Is II a it a—jneI rcjlnewT

40

GE 1-983 38

iU*4• ‘>**I,iIU*1.I —A *4 J At

Figure 11 (0178A8176)curves for the M2 unit

relay

Operating timein the GCY51A

Figure 12 (0178A8177) Minimum steady-state operating characteristics of the

0M3 unit

/

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//

N/ i\

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I //

/1

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IN

‘0

64)

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—I

ar. All nAil IpAna.) WI/uIinil N JIlT IN 1111 (i1A RI LAY

All liIPI HI rUALr-, 1I(!I 0*19’ NTION I 0. I NAIl III (1*4 uNTIL ItI*IIJI411* II I’’ In,’ 04 * AKIN WIT)) 111*400

liii 1*4111 41 N UN, N, I 01• I MAIlS 1’ RI’ I I

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= I (0

Fr

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1

I- -5 4. I- 4*1I I *411 /14/1./111 I N rn/tOIL

Figure 9 (0178A8174) Minimum steady- Figure 10 (0118A8175) Steady-state andstate operating characteristic of M2 unit dynamic reach curves for the M2 unit

of the GCY51A relay

/

\\

41

GEI—98338

i. ,;-I

• ‘;L,L..77’ ,_.j,7)1 CTII FT. LI A’

t

“•1’.‘:.. ._..1__._

—w7A711 FFPT 77 LT7T,S. -,--.

Figure 13 (0178A8178) Steady—state anddynamic reach curves for the 0M3 unit

with offset at zero

Figure 1. (0178A8179-1) Steady—statereach curves for the 0143 unit with offset

at 0.5 ohm

4 . -: —. ‘— ,: I:: ‘

tiL ‘‘‘.2. :I::.:.:.’lE..L. yin’ .:I*,tv.t* FL7*TW TrW 77 (. (

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______

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Figure 15curves for

showing

(0178A818o)the 0M3 unittime to close

contact

Operating timewith zero offsetnormally-open

Figure 16 (0178A8181) Operating timecurves for the 0M3 unit with 0.5 ohm offset

siowing time to open the normally-closed contact

‘L[

,

_

EL

i:

:TT.’TTT.I f’Tn’n’’yiTn’EJE:T_ I 1 in -

Wi7- .A , ii’ .7..

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W:t4

42

GE I- 98338

, /

\\ /‘1 I---t&_

7

/

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--

Figure 17 (0178A8182) Impedance Figure 18 (0178A8183) Impedancecharacteristics of Mi, M2, and 0M3 units craracterjstics of M1, M2, and aM3 unitsfor a typical step distance application for a typical directional comparison

pilot relaying application

CONNECTING PLUG MAIN BRUSH CONNECTING BLOCK

u

[US

I

— AUXILIARY BRL’SH TERMINAL BLCCK\C.14 ,.HU Ci1IA/MI,I SiUBTING

NOTE Al 1 ER ENGC ING ALIX LIARY BRUSH, CONNI CTNG LUG

_jJ_ TRAUIELS I/I INCH BEFORE ENGAGING THE MAIN LRLTI ONTHE TERMINAL BLOCK

Figure 19 (0178A7169-1) Schematic diagram Figure 20 (8025039) Cross section of caseof typical two—terminal line and cradle block showing auxiliary

43 brush and shorting bar

IN

0u

rInternal connections (front view) of type GCY5IA relay

GEI-98338

11 13 15 11612 20

I NPIJT

0M30M3

M2 RESTR.

0M3 PESIR.

Tf?—1

OFFSET

2SHORT FINGER

Figure 21 (0178A7049-3)44

LE:HZ‘F ‘j

FF FF’ .

GEI-8338

Figure 22the type

(0178A8184) Test circuit forGCY51A relay using a phase

shifter.

FigLre 23 (0178A8185) Schematic didgranlof GCY test circuit

• ‘I ;‘ I! -‘ tI

NN ‘‘“ F ,‘‘•,, —JIF IF.E lIT

‘I’NT. IV’ KU -‘14-IN &N’ -

F?

Figure 24 (0178A8186) Connections forfield testing of the type GCY51A relay

using type XLA test plugs

Figure 25M1, M2,

(0178A8187) Reach of mho unitor 0M3 at the angle of the

test reactor

‘ ‘F

‘LI-I I

--------- .HL_ri

I---,FFI,I,-LIFILN’

F-F

-

F” i1uo:

f• T I

111 FIPI FIlL

NT (O1F F VD ‘ALl

ANti rR(ç. III,

P

I L

10%

-----A1 - - -

- IcY -2U

NOTE10)1110 LINET S’IQAE OPT’ONAL C(’NNECIIONT TA TAil-LUEOILAPI7ING CINCIJIT Till-CULT 441CM FAULT VOlTA-Ct.PlIv[ INT[RNAL lilA-PIP’, EIT4IFIN 17-19 ANTIl-A—tiC NIl-ION LII NT r*J1tD l)IINl- (•‘ (14).

2 7MIN4 TAP

45

GEI-98338

-—

-;;-;-0 00. I l0.001 !._00.!_

I) — I •* *0 —

101 — I — ‘— ‘— 0IO 0— •0_‘

II • JL.. 1 * ‘‘ !‘I__ !!__ .i.__0000*) *1*01)4 *0) *0*00 111IAICI I 0 II

;14 *101(1*141% 0* 0*0*1 lOGO * 140111(0*1IS,040I0)*OGLI 0 51 4110.1+ ‘0* CUIMOT 00*0* 000

oflT141 Ill, Tot *1,0*1*00 00)01010*100 •0050 low) 000.100.1100 00*1! 1*00*1 1100 0)10 10*

000*100 *00* (000*0.110)1 004 0*70! 0)001 01.01 tIp*1007. 14.41*0’ 0* SOOt 0)4*11*141*

Figure 26 (0178A8188)checking offset of

Connections forthe 0M3 unit

F re 27 (0178A8189) Test connectionsfor overall test of type GCY51A relays

TOG

PINC

$10.1 IO*4M)Y

CCtUC I - -

/7

-MDVI.

-

O)4CKSTOP

Figure 28 (8034958) Four pole induction cylinder unit typifying construction ofthe Ml’ M2, and 0M3 units in the GCY51A relay

© © ©1l

fl00LlI00410* 00*400

II

4*_so j 00_I)? Ill—ISO Iol—)*•n 1—0)4 ITO—Ill 411+344

1)4 1’

)4S.- “I-’’

46

GIEI-98338

7 5300000

‘00000‘]0 8 6 4 2

MMCUTOUT H .M t37MM)iREPLACE IA6S

DRLLED2SH’LES

(OPT13NAL) I (—.-

PANEL (IS

342MDI

I3.c(4H LES)II’,

(ZL.SOOI(88 M

9.50—

- (19MM)(6MM) 3DRILL

‘Z50 4

______ ___

0 H DL ES

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OTH ENDS

(6MM)(12MM’) ‘

.250.500 T Y P C &

PANEL DRILLING FOR SURFACE MOUNT 1NG(FONT VIEW

Figure 29 (6209276-3) Outline and panel drilling dimensions for type GCY51A relay

NUMBERING OF STUDS(BACk VIEW)

—i9 17 1513 II \00000

0000020 IS 1614 12

ILL. .7S

)MM)7 S

(502MM)- 19.75

-

(44MM)—1.75

VIEW SHOWINC,ASSEMBLY OFHARDWARE FORSURFACE MTGON STEEL PANELS

PANEL DRILLING FOR SEW-FLUSHMOUNTING(FRONT VIEW)

)

47

GE Power Management

215 Anderson AvenueMarkham, OntarioCanada L6E 1B3Tel: (905) 294-6222Fax: (905) 201-2098www.ge.comlindsyslpm