GE GCX51A Instructions Manual Download Page 1

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Summary of Contents for GCX51A

Page 1: ...GEI 98328J INSTRUCTIONS DIRECTIONAL DISTANCE REACTANCE RELAY TYPES GCX51A Forms 11 and up GCX51B Forms 11 and up GENERAL ELECTRIC Courtesy of NationalSwitchgear com ...

Page 2: ...aximum Torque Other Checks and Tests OHM Unit Transfer Relay OX Target Seal in Unit INSTALLATION PROCEDURE Location Mounting Connections Visual Inspection Mechanical Inspection Electrical Check Tests on Induction Units Testing the OHM Unit Testing the MHO Unit Other Checks and Tests Overall Tests PERIODIC CHECKS AND ROUTINE MAINTENANCE Contact Cleaning SERVICING MHO UNIT 12 14 15 15 16 16 16 16 17...

Page 3: ...omes a more significant part of the total impedance from the relay to the fault as the protected line length gets shorter It is for this reason that the GCX type of characteristic is ideally suited for the protection of short transmission lines However the GCX51 relays may also be applied on longer lines if the range of the relay permits the required reach settings It will be noted in the section ...

Page 4: ...he distance to the nearest remote terminal The second zone units should be set to reach at least 110 of the distance to the farthest remote terminal including the effects of infeed if present The third zone MHO units should be set to reach sufficiently farther than the second zone units to provide for accommodating arc resistance at the second zone balance point The third zone MHO units sometimes ...

Page 5: ...ch of the OHM unit is determined by the No 1 leads second zone reach by the No 2 leads and the reach of the MHO unit by the L leads E The GCX51B relay includes an instantaneous overcurrent unit identified as OC on The short reach form of the GCX51 is the internal connection diagram Figure 8 normally furnished with an OC unit having a 4 16 ampere calibration range standard reach form is available w...

Page 6: ...ing the equation reduces to the following expression in terms of impedance 1 Y cos 0 0 K cos 0 0 K Thus the unit will pick up at a constant component of admittance at a fixed angle depending on the angle of maximum torque Hence the name MHO unit or Z OHM Unit The OHM unit of the GCX51 relays is also of the four pole induction cylinder construction see Figure 14 with schematic connections as shown ...

Page 7: ...e unit at the angle of maximum torque see Table II under RATINGS is obtained when the E restraint taps are on 100 The ohmic reach can be extended by reducing the percentage of the fault voltage applied to the restraint circuit that is by setting the E restraint taps on a lower percentage position on the tap block The ohmic reach of the unit at the transmission line angle which will usually differ ...

Page 8: ...e fault must be right at the relay bus and therefore to protect for this fault it is imperative that the relay reach zero percent 0 of its setting Figure 7 shows that the MHO unit under static conditions will not see a fault at zero percent 0 of the relay setting regardless of the tap setting However under dynamic conditions when the memory action is effective Figure 7 shows that a 2 5 ohm MHO uni...

Page 9: ...nitude ratio of fault impedance to relay reach and whether relay voltage prior to the fault is at rated 120 volts or is zero 0 A series of figures is included at the rear of the book showing operating time of the MHO unit and overall operating time of the relay for a number of typical conditions The operating time of the MHO unit is given separately because this unit is frequently used for the car...

Page 10: ...fted to 95 in which case the output setting would be 95 9 5 or 10 which of course can be set exactly For OHM Unit Transfer Auxiliary The OHM unit transfer auxiliary OX is a telephone type relay whose coil and contacts are shown on the right in the internal connection diagram of Figure 8 The unit is mounted at the top of the relay and is used to change the setting of the OHM unit to provide a secon...

Page 11: ...it No 1 Tap Setting 2 VA a jb Input Tap Setting MHO Unit E2 Tap Setting 2 e jf VA c jd Input Tap Setting The terms a jb and c jd represent the burdens of the OHM and MHO unit restraint circuits with input and output taps on 100 The term e jf represents the burden of the MHO unit polarizing circuit The values of these terms are given in Table VII TABLE VIIA POTENTIAL BURDENS 60 Cycles Frequency Rat...

Page 12: ...UNIT SETTINGS ON THREE TERMINAL LINES Set for 90 of the reactance to the nearest remote terminal Do not include the effects of infeed or Set for 90 of the total line With all three terminal breakers closed calculate the effective reactance seen by this unit for a three phase fault at one of the remote terminals Repeat for a fault at the second remote terminal Include the effects of infeed in both ...

Page 13: ...tained from the following equation Xmin x 100 T XL where T 1 tap setting in percent Xmin Basic reach tap setting of reactance unit X _ Desired reactance reach in secondary phase to neutral ohms If we assume that it is desired to set the first zone for 90 of the distance to the remote terminal then X _ 0 9 0 80 0 72 Secondary ohms For this ohmic reach use a 0 5 ohm basic reach tap setting Thus Xmin...

Page 14: ...a reach is 2 5 x 100 cos 60 80 85 5 Set the thircTzone E taps for 86 Note that the restraint tap setting of the MHO unit must not be set for less than 25 Also refer to Appendix I for possible further limitations on the MHO unit reach setting The instantaneous unit setting should be no lower than 115 of full load current In this case with 600 5 CT s and a maximum load current of 450 amperes the ins...

Page 15: ...ircuit components measurement 2 This unit provides accurate first or second zone distance The top element includes the OHM unit transfer auxiliary OX the combination target and seal in unit the transactor associated with the OHM unit potential circuit the tapped autotransformer that determines the reach of the OHM and MHO units and in the case of the type GCX51B relay the instantaneous overcurrent...

Page 16: ...Electrical Checks Before any electrical checks are made on the OHM and MHO units the relay should be connected as shown in Figure 10 and be allowed to warm up for approximately 15 minutes with the potential circuit alone studs 17 18 energized at rated voltage and with the E2 and No 1 taps set at 100 The units were warmed up prior to factory adjustment and if rechecked when cold will tend to underr...

Page 17: ...ections of Figure 10 will still be used with the E2 taps still at 100 and the voltage set at the value shown in Table XI for the relay to be checked The pickup should then be checked with the current displaced 30 from the maximum torque position in both the lead and lag direction Set the phase shifter so that the phase angle meter reads 330 Note that while the phase angle is being set the current ...

Page 18: ...tage by 45 Again vary the voltage across studs 17 18 until the point is found where the OHM unit contacts just close These points are listed in Table XII for the standard and short reach forms of the relay in the column headed 45 A 3 variation is permissible Note that the relays are normally shipped from the factory with the basic minimum reach adjustment taps on the intermediate setting that is 0...

Page 19: ... the vacant position in the left hand plate If this procedure is followed the contact adjustments will not be disturbed 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 facilitate inspection and testing Mounting The outline and panel The relay should be mounted on a vertical surface drilling ...

Page 20: ...erred to GET 3474 a Testing the OHM Unit To check the calibration of the OHM unit it is suggested that the portable test box Cat No 102L201 portable test reactor Cat 6054975 and test resistor Cat 6158546 be arranged with Type XLA test plugs according to Figure 12 These connections of the test box and other equipment are similar to the schematic connections shown in Figure 11 except that the Type X...

Page 21: ...in the test is actually 2 1 ohms The percent tap of the test box autotransformer at which the OHM unit contact will just close can be calculated as follows 100 68 6 Tap The OHM unit should therefore theoretically close its contact with the test box autotransformer taps set at 68 and remain open with the taps at 69 A range of 67 to 70 is acceptable The phase angle of the OHM unit reactance characte...

Page 22: ...lay 2 E m n cos p e where 0 angle of test reactor impedance 9 MHO unit angle of maximum reach The test box autotransformer percent tap for MHO unit pickup is then given by the equation 2ZRelay 100 Tap ZL As an illustration of the above the example in the section on CALCULATION OF RELAY SETTINGS will again be used In this example the E2 tap setting was calculated to be 86 and since a standard reach...

Page 23: ...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 60 and 30 respectively will be available for checking the MHO unit reach at the 60 and 30 positions The MHO unit ohmic reach at the zero degre...

Page 24: ...se is the most important consideration For third zone backup protection the MHO unit is the measuring unit but for remote faults the voltage at the relay is not apt to be low and furthermore the accuracy of a third zone backup unit is not as important as that of a first zone unit In addition to the above tests on the MHO unit it may also be checked for directional action with the test box circuit ...

Page 25: ...ds 17 18 19 20 Mho unit Rating Slips between 50 57 amps Slips above 60 amps 2 5 Ohms 1 0 Ohm The clutch on either unit can be adjusted by inserting a special flat open end wrench underneath the green composition head directly above the spool body of the front coils so that it engages with the flats on the molded spacer on the cup shaft Hold this wrench and with a 5 16 open end wrench loosen or tig...

Page 26: ...es the cleaning of the actual points of contact knives files abrasive paper or cloth of any kind to clean relay contacts Its Do not use SERVICING If it is found during the installation or periodic tests that the OHM or MHO unit calibrations are out of limits they should be recalibrated as outlined in the following paragraphs laboratory The circuit components listed below which are normally conside...

Page 27: ... unit can be adjusted by means of rheostat R3 which is identified in Figure 1 Increasing R3 by turning the screwdriver adjustment in a counterclockwise direction increases the reach of the unit Connect the relay as shown in Figure 10 Set the E2 taps in the 100 position and with the current at 5 amperes and voltage at 120 volts set the phase shifter so that the phase angle meter reads 300 i e curre...

Page 28: ...orque 90 current lagging voltage may be adjusted by means of rheostat R2 It should be noted however that these adjustment are not independent that is an adjustment of R2 will have some effect on the reach of the OHM unit and adjustments of Ri will affect the angle of maximum torque To calibrate the OHM unit place the No 1 taps in the 100 position and use the connections shown in Figure 10 Follow t...

Page 29: ...the value 1n Table XIV under the 45 column Modify the R2 setting until the operating voltage 1s within this 1 limit Step 3 The OHM unit contacts should close within 2 of the voltage If the OHM unit contacts do not close within these Recheck Step 1 listed in the 90 column limits repeat steps 1 and 2 until the OHM unit contacts close within the limits specified RENEWAL PARTS It is recommended that s...

Page 30: ...ore the Fault is Zero Volts Operating Time Curves for 2 5 Ohm MHO Unit in the Standard Reach Relay When the Relay Voltage Before the Fault is 120 Volts Operating Time Curves for 2 5 Ohm MHO Unit in the Standard Reach Relay When the Relay Voltage Before the Fault is Zero Volts Operating Time Curves for Short Reach GCX51 Relay Basic OHM Unit Reach 0 1 Ohms Voltage Before the Fault 120V Operating Tim...

Page 31: ...asic OHM Unit Reach 1 0 Ohm Voltage Before the Fault Zero Volts Test Connections for Overall Test of the GCX51 Relays Outline and Panel Drilling for GCX51A and GCX51B Relays Magnet and Coil Assembly R X Diagram Illustrating Response of GCX51 Relay to Phase to Phase Fault on Adjacent Phase Pair Curves for Determining Maximum Safe Setting of MHO Unit in GCX51 Relay Curves for Determining the Correct...

Page 32: ...R 3 MHO UNIT R 4 Figure 1 8034914 Type GCX51A Relay Removed from Case Front View m TAPPED TRANSFORMER C e TAPPED TRANSACTOR 0 gh i 5 r f w T r vJi n 1 L TERMINAL BLOCK FOR OHM UNIT f n i i t f I M r f t f T 1 1 to TERMINAL BLOCK FOR MHO UNIT I T I f ift j Ai 1 Figure 2 8034917 Type GCX51A Relay Removed from Case Rear View 32 Courtesy of NationalSwitchgear com ...

Page 33: ...EACTANCE UNIT R IIDAH QC g A v i g 9 I 4 K K 6209272 0176A7Q92 OX ZONE TRANSFER AUXILIARY FOR O AC 633 HGA1AAV 3AC CONNS K 64QC533 TARGET AND SEAL IN T SI H A AAL IfRCNT CONKS TRIP CTIcirP 1 C 2L2185 2 3774239 377 139 1D A llh TIVINC PELAY 21 ZONE I ZQsOr ZONE IARGEI 125V If 4A8584 T 1 T 2 T 1QA A3t b4 T 31 PTPT r rf j 1C2I 21r6 1 25CV TU TIMING ELEMENTS FIRST TIMING CONTACT TO CLOSE n 2 SECOND TI...

Page 34: ...Lfc B B2 Bl B RESTR El P0LE2 hi B3 OPER El E2 POL B2 B3 E2il E3 B2 B1 BM K TUB B BACK B POL POL B E POT POT TR TR t i2 1 f ii OHM UNIT TOP VIEW MHO UNIT TOP VIEW Figure 4 0116B6856 1 Schematic Diagrams of MHO and OHM Units used in Type GCX51 Relays 34 Courtesy of NationalSwitchgear com ...

Page 35: ...OHM MHO UNIT IN THE SHORT REACH GCX51A AND 8 RELAYS OATA TAKEN FROM PHASE TO PHASE FAULT AT MHO UNIT ANGLE OF MAXIMUM T0RQUE 60o LAG r uJ if 60 i STATIC CHARACTERISTIC DYNAMIC CHARACTERISTIC 120 VOLTS BEFORE THE FAULT Li O naiaaaaiaai 50 T E2 TAP SETTING t THREE PHASE FAULT CURRENT 1 5 cc 40 I 30 J 4 t 20 10 iliimiiilllilliillliiiillllilliliili III P 50 25 30 35 1 30 FAULT CURRENT UN AMPERES 40 45...

Page 36: ...I i ii1 F 4 4 H 1 z TAP SETTING THREE PHASE FAULT CURRENT 4 f Ft i t F i F m 4 4 m t T H r i m 1 F H mi FFFi limit 4 1 m 4 t Hi H 1 i 8 V H ii I t 4 L 4 f 4 44 I f r f m i II f t 8 H 5 4Tt J ff it j 4 n 4 f Ffi 5 44 1 4 I n 44 4 tt F4 4 H 44 T it 4ft a H t Eiiisi 4 4 4 4 Hi 4 H f tt 4 H 4 F ii 1 Hi I a i z i 4 1 t i 4 Hi i 4 4 5 4 4 4 XL tl 4 w r H 5 40 35 20 25 o 0 5 1 0 FAULT CURRENT IN AMPERES ...

Page 37: ...TRAINT 1 0 6 3 WHEN USED O r O 9 1 3 5 7 o o u 10 2 6 8 IF STUD II POLARITY IS NEGATIVB SHORT FINGER NOTE A REVERSE POLARITY OF RECTIFIER BY INTER CHANGING GREEN LEADS Figure 8 0203A8583 5 Internal Connections Front View of the Type GCX51A or GCX51B Relay BUS A BUS B 1 2 0 14 j 0 80 OHMS M ILE Figure 9 0178A7169 1 Schematic Diagram of Typical Two Terminal Line 37 Courtesy of NationalSwitchgear com...

Page 38: ... C O K N E C T T O T E R H I N f t L S Q M T H E R E K R O F R E L A V C f S HIGH INPUT IMPEDANCE VOLTMETER Figure 10 0165A6069 2 Test Circuit for GCX51A and GCX51B Relays Using a Phase Shifter RS xs oGCX 17 SF 1 RATED VOLTAGE AND FREQ TA L 10 oGCX 18 1 o vA o GOAlO 8 T t Figure 11 362A624 2 Schematic Diagram of GCX Test Circuit 38 Courtesy of NationalSwitchgear com ...

Page 39: ...LT SWITCH 11 13 15 17 19 I I I I 18 20 I I L I TAP SW CONN FOR ZONE 3 10 TEST 1 r n ZONE I 7 9 TEST TAP SW ZONE Z 1 d 10 1 TEST r J C T SHORTING I BARS I TEST BOX J L LOWER TEST PLUG t T TARGET ZONE 2 SIGNAL SIGNAL ZONE 3 SIGNAL ZONE 1 SIGNAL Figure 12 0178A7162 1 Connection for Field Testing the GCX51A and GCX51B Relays Using Type XLA Test Plugs 39 Courtesy of NationalSwitchgear com ...

Page 40: ...t Reactor 362A625 5 Reach of the MHO Figure 13 PIVOT ASSEMBLY SPRING ADJUSTING RING STATIONARY CONTACT MOVING CONTACT BACKSTOP Induction Cylinder Unit Typifying Construction of the GCX51 Relays Four Pole the OHM and MHO Units in Figure 14 8034958 40 Courtesy of NationalSwitchgear com ...

Page 41: ... 2C T 2C 4 t iTTEiliE ti tr t i f rr 1rr EE11 r r t 19 19 i 4 OPERATING TIMES OF 2 5 OHM MHO UNIT WITH 60 ANGLE OF MAXIVAJM TORQUE AN0 100 TAP SETTING 85 LAG 60 LAG OPERATING TIMES OF 2 5 OHM WHO UNIT WITH 60 ANGLE OF MAXIMUM TORQUE AND 100 TAP SETTING 18 18 1 Er in B 17 r 17 SOURCE IMPEDANCE PHASE ANGLE FAULT IMPEDANCE PHASE ANGLE m 85 LAG 60 LAC n SOURCE IMPEDANCE ANGLE FAULT IMPEDANCE ANGLE 1 i...

Page 42: ...DANCE 85 LAG ii T RELAY VOLTAGE BEFORE THE FAULT 0 VOLTS 1 18 1 li AVERAGE OPERATING TIME OF GCX51A RELAY i RASIC OHM UNIT REACH 0 2 0HAS n i NO 1 6 E2 TAP SETTINGS 100 ANGLE OF MAXIMUM TORQUE 60 H SOURCE IMPEDANCE A FAULT IMPEDANCE 85 LAG r t RELAY VOLTAGE BEFORE THE FAULT 120 VOLTS iiii ii P i r ui Iiii nrt 4 irt H ill t Iiii Ii 2 i m CD r 16 Hit 52 i 1 1 4 1 HI rrh in Hijjji i ll ill iii 1 i m ...

Page 43: ...1 R e l a y B a s i c OHM U n i t R e a c h 0 4 O h m s V o l t a g e B e f o r e t h e F a u l t 1 2 0V F i g u r e 2 4 0178A7148 O p e r a t i n g T i m e C u r v e s f o r S h o r t R e a c h GCX5 1 R e l a y B a s i c OHM U n i t R e a c h 0 4 O h m s V o l t a g e B e f o r e t h e F a u l t Z e r o V o l t s l Ft u n jasEUc 1 H t r 4 rr J Hp t rtrr n m 20 TT tm AVERAGE OPERATING TIME OF GCX5...

Page 44: ...e Fault Zero Volts Figure 27 0178A7146 Time Curves for Standard Reach GCX51 Relay Basic OHM Unit Reach 0 5 Ohms Voltage Before the Fault 120V Operating 10 J iCCMilMilalmi if niiaiM 18 W3IC CM UNIT REACH 1 0 0MB NO 1 A E2 TAP SETTINGS 100 HJANCLF OF MAXIMA TORQUE 60 IMPEDANCE A FAULT IMPEDANCE BSP LAG VOLTAGE BEFORE DC FAULT 120 VOLTS 9 17 16 8 ft tn tt to to CD 15 9 to 14 o 2 S 13 g 12 O fc 11 c f...

Page 45: ...VAR KW OUT KW t KVAR DIRECTIONS WlTH RESPECT TO THE BUS OUT KVAR IM 1 1 nux KM mu 240 aux 330 60 105 150 285 cn X TO A Y TO B 15 60 105 150 195 240 285 330 o 30 75 120 210 165 255 300 345 X TO C Y TO D o 75 120 165 210 255 300 345 30 UJ PHASE SEQUENCE 1 3 2 o CJ 30 75 120 210 255 165 300 345 X TO A Y TO B 120 345 75 165 210 255 300 75 t 330 15 195 240 60 105 150 285 X TO C Y TO D UJ 15 60 240 285 ...

Page 46: ...l l i n S U j l 1 1 1x724 1 MM _ M 3 50 fH T r 5 9 50 A 241MM t 93 252MM 7 781 I 198MM I L t i CUTbUT T I JL 19 75 502MM 5 562 396MM i 19 875 504MM 88MM I f i 1 468 37MM 1 h 718 18MM 250 2 843 72MM 6MM 500 12MM TYPICAL 218 218 5 25 5MM 5MM 133MM 5 687 3 4 DRILL 20 HOLES 19MM PANEL 144MM PANEL DRILLING FOR SURFACE MOUNTING FRONT VIEW PANEL DRILLING FOR SEMI FLUSH MOUNTING FRONT VIEW CASE 5 16 18 ST...

Page 47: ... OR CORE B MAGNET COILS C WAVE WASHERS D OCTAGON NUT FOR CORE ADJUSTMENT E FLAT WASHER F CORE HOLD DOWN NUT HEXAGON B r 3 3 i f I Fn B v C D E F Figure 33 0208A3583 Magnet and Coil Assembly 47 Courtesy of NationalSwitchgear com ...

Page 48: ...above it is necessary to limit the reach setting of the MHO unit In order to do this it is necessary to know where along the TP line the impedance seen by the unfaulted phase relay terminates Referring to Figure 1 1 and with everything plotted in terms of secondary ohms the secondary impedance TP is equal to V3 ST where ST is the vector sum of the system impedance behind the relay OS plus the impe...

Page 49: ...the maximum setting of ZMO 9 3 0 72 6 7 ohms This is on the basis of no load current and must be further corrected as determined by the ratio of fault current to load current as shown in Figure 1 3 If the ratio of the fault current to maximum load current is 5 find the point on the curve for this ratio corresponding to Xs Xpu 2 1 This yields a value of 0 83 and the maximum permissible Mho unit set...

Page 50: ... 6 0 8 1 0 0 1 0 2 0 3 0 4 RATIO OF X Xfcu Figure 1 2 0178A8100 0 Curves for Determining Maximum Safe Setting of MHO Unit in GCX51 Relay J P Hf THTT 4 f i TF t 4 ME t Figure 1 3 0227A2675 0 Curves for Determining the Correction Factor of the GCX51 Relay 50 Courtesy of NationalSwitchgear com ...

Page 51: ...Courtesy of NationalSwitchgear com ...

Page 52: ...å å å å 3RZHU 0DQDJHPHQW 215 Anderson Avenue Markham Ontario Canada L6E 1B3 Tel 905 294 6222 Fax 905 201 2098 www ge com indsys pm Courtesy of NationalSwitchgear com ...

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