Alstom MBCH, Service Manual

Page 1: ...Service Manual Type MBCH Biased Differential Relay ...

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Page 3: ...circuit board Avoid touching the electronic components printed circuit track or connectors 3 Do not pass the module to any person without first ensuring that you are both at the same electrostatic potential Shaking hands achieves equipotential 4 Place the module on an antistatic surface or on a conducting surface which is at the same potential as yourself 5 Store or transport the module in a condu...

Page 4: ... Connections for checking relay settings 30 Figure 2 Connections for checking relay operating time 30 Figure 3 Connections for checking the bias curve 31 Figure 4 MBCH 12 13 16 bias curve 32 Figure 5 Connections to the relay to simulate magnetizing inrush current waveform 33 Figure 6 Mesh busbar arrangement requiring three bias inputs to the differential relay 34 Figure 7 Three winding transformer...

Page 5: ...1 Figure 14 Block diagram biased differential protection relay Type MBCH13 with three biased inputs 42 Figure 15 Block diagram biased differential protection relay Type MBCH16 with six biased inputs 43 Figure 16 Connection for six change over tripping contacts for three phase tripping of up to six circuit breakers 44 6 COMMISSIONING TEST RECORD 45 REPAIR FORM 47 ...

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Page 7: ...sub assembly eg power supply Note The term earth used throughout the product documentation is the direct equivalent of the North American term ground Installing Commissioning and Servicing Equipment connections Personnel undertaking installation commissioning or servicing work on this equipment should be aware of the correct working procedures to ensure safety The product documentation should be c...

Page 8: ...oltage produced may be lethal to personnel and could damage insulation External resistors Where external resistors are fitted to relays these may present a risk of electric shock or burns if touched Battery replacement Where internal batteries are fitted they should be replaced with the recommended type and be installed with the correct polarity to avoid possible damage to the equipment Insulation...

Page 9: ...ge hazards Hazardous live voltages may be accessible on the extender card Insertion and withdrawal of heavy current test plugs When using a heavy current test plug CT shorting links must be in place before insertion or removal to avoid potentially lethal voltages Decommissioning and Disposal Decommissioning The auxiliary supply circuit in the relay may include capacitors across the supply or to ea...

Page 10: ...0 A2 1995 Distribution level fixed Category Category III installation Equipment in Overvoltage EN 61010 1 1993 A2 1995 this category is qualification Category III tested at 5kV peak 1 2 50µs 500Ω 0 5J between all supply circuits and earth and also between independent circuits Environment IEC 61010 1 1990 A2 1995 Compliance is demonstrated by Pollution degree 2 reference to generic safety EN 61010 ...

Page 11: ...ilable are as follows Type No of bias Publication designation circuits Application ref no MBCH12 2 Two winding power transformer R6070 MBCH13 3 Generally 3 winding power transformer where bias is required R6070 for each of the 3 groups of CTs MBCH16 6 For all applications requiring R6070 4 5 or 6 bias circuits Section 2 INSTALLATION 2 1 General Protective relays although generally of robust constr...

Page 12: ...on may on subsequent unpacking find its way into the relay in damp conditions the carton and packing may become impregnated with moisture and the de humidifying agent will lose its efficiency The storage temperature range is 25 C to 70 C 2 4 Site The installation should be clean dry and reasonably free from dust and excessive vibration The site should preferably be well illuminated to facilitate i...

Page 13: ...ure that the case earthing connection above the rear terminal block is used to connect the relay to a local earth bar 3 1 5 Insulation The relay and its associated wiring may be insulation tested between all electrically isolated circuits all circuits and earth An electronic or brushless insulation tester should be used having a dc voltage not exceeding 1000V Accessible terminals of the same circu...

Page 14: ... expected current ie 0 09 to 0 11A for a 1A relay or 0 45 to 0 55A for a 5A relay with a 10 relay setting Check that the relay trip contacts terminals 1 3 and 2 4 are closed with the current above the setting and that these contacts open as the current is removed Check also that the relay alarm contacts terminal 9 11 are closed with the current above the setting and remain closed as the current is...

Page 15: ...tes as indicated by the front plate LED Record the values of current A1 and A2 Calculate the mean bias using the formula A2 2 Use the bias curve Figure 4 for MBCH 12 13 16 to determine the theoretical differential current and check that the measured current A2 is within 20 of this theoretical value Note that for a 5 amp relay In 5A the values of the calculated mean bias have to be divided by 5 bef...

Page 16: ...he load current Check that the load current in each bias coil is close to the value which is expected for the particular application For the MBCH 16 relay particularly it may be preferable to energize the transformer in different ways to ensure that all connections are satisfactory Check that the differential current under any of these conditions is within 1 20 of the load current The actual figur...

Page 17: ...cuit breakers as in mesh or one and a half breaker arrangements See Figure 6 MBCH 16 6 For applications requiring 4 5 or 6 bias circuits See Figure 8 4 2 Matched line current transformers For optimum performance the differential scheme should be arranged so that the relay will see rated current when the full load current flows in the protected circuit Where line current transformers are matched bu...

Page 18: ...sformers The winding details of the three current ratings of the matching transformers are given in the table below and in Figure 10 Number of turns Transformer rating Primary tap terminals 1 1A 5 1A 5 5A 1 2 5 1 1 2 3 5 1 1 3 4 5 1 1 4 5 5 1 1 5 6 125 25 25 X 7 25 5 5 7 8 25 5 5 8 9 25 5 5 S1 S2 125 125 25 S3 S4 90 90 18 Table 1 Notes on combinations of windings For star output windings It is per...

Page 19: ...103 Because the 11kV winding is delta connected the associated current transformers will be star connected and under rated load conditions will give the following current per pilot phase 1574 6 x 1A 1600 This current is sufficiently close to the relay rated current 1A and furthermore requires no phase correction 66kV winding 30 x 106 3 x 66 x 103 Normally the current transformers associated with t...

Page 20: ...igure 13 The voltage and power rating of each winding is indicated The current transformer ratios are chosen as a function of the winding voltage and power rating of the particular windings with which they are associated For transformer differential protection matching of current transformers is correct when the CT ratios are determined on a basis of associated winding voltage only 500kV Winding B...

Page 21: ... associated with the 138kV star winding and thus the necessary transition to delta connection must be made by means of an interposing CT The output windings S1 S2 and S3 S4 of the interposing transformer must be connected in series to give a total of 43 turns see Table 1 The number of primary turns Tp should be Tp x Ts 17 73 say 18T Table 1 indicates that primary tap nos 2 9 should be used with li...

Page 22: ...duce the 17 17A output to 5A Using S1 S2 and S3 S4 in series as output winding the primary tap becomes Primary turns Tp x Ts Tp 12 52 say 13T Table 1 indicates that primary taps nos 2 8 will give 13 turns with link X 5 instead of X 6 In 17170 2A Is 17 17A 17170 2 x 5 5000 Is Ip S3 A B C To 138kV line current transformer P1 P1 P1 A B C N S1 S1 S1 S2 S2 S2 S3 S3 S4 S4 S4 P2 P2 P2 9 5 x 2 9 5 x 2 9 x...

Page 23: ...imum spill current with through load current should generally be kept below 20 of relay rated current allowing for CT mismatch and possible tap changer operation This may be achieved either by appropriate choice of main line current transformers or by the use of interposing transformers as descibed in Section 4 Where higher levels of spill current exist the relay setting may need to be increased ...

Page 24: ...s to be working correctly Conclusion Faulty pcb1 Apply correct auxiliary dc voltage Check internal dc rails Conclusion Internal wiring faulty and or pcb 1 2 or 3 faulty Is relay operation on magnetising inrush current incorrect Correct Check auxiliary dc current drain Correct Correct Follow Flowchart 6 Follow Flowchart 2 Apply correct dc voltage Suspected faulty module NO NO NO YES NO YES YES YES ...

Page 25: ...d 28 Monitor tripping contacts Conclusion faulty pcb 1 pcb 2 or transformers T1 or T2 Conclusion faulty pcb1 Conclusion faulty pcb1 Follow Flowchart 4 Follow Flowchart 3 Monitor R2 Inject In into terminals 27 and 28 R2 voltage correct Do tripping contacts close TP4 voltage correct YES YES YES YES YES YES NO YES YES NO NO NO ...

Page 26: ...als 25 and 28 Conclusion Faulty transformer T3 Conclusion Faulty pcb1 Conclusion Faulty pcb1 pcb2 or transformer T3 Link terminals 24 and 27 Inject In into terminals 23 and 28 Conclusion relay appears to be functioning correctly R1 voltage correct TP4 voltage correct TP4 voltage correct YES YES YES YES YES YES NO NO NO ...

Page 27: ...ion Relay appears to be functioning correctly Conclusion Faulty pcb1 pcb2 or transformer T3 NO YES NO NO NO YES YES YES TP4 voltage correct note 3 TP4 voltage correct note 3 TP4 voltage correct R1 voltage correct Monitor R1 Note 6 Inject In into terminals 23 and 28 Conclusion Faulty pcb1 YES R1 voltage correct Monitor R1 Note 6 Inject In into terminals 21 and 28 Conclusion Faulty pcb1 Conclusion F...

Page 28: ... 28 Conclusion Faulty pcb1 Monitor R1 inject In into terminals 1 and 28 Conclusion Faulty pcb1 pcb2 or transformer T7 Conclusion Relay appears to be functioning correctly Conclusion Faulty pcb1 pcb2 or transformer T6 NO YES NO NO NO NO NO YES YES YES YES Conclusion Faulty pcb1 YES Conclusion Faulty pcb1 pcb2 or transformer T8 R1 voltage correct note 6 TP4 voltage correct note 3 R1 voltage correct ...

Page 29: ...ing inrush current flows into the power transformer Monitor R2 note 4 Inject In into terminals 27 and 28 Monitor TP2 note 7 Inject 0 5In into terminals 27 and 28 Conclusion Faulty pcb1 pcb2 or transformer T1 Conclusion Faulty pcb1 YES YES YES YES YES NO NO TP2 Voltage correct R2 Voltage correct ...

Page 30: ...l Overcurrent test set 25 27 26 28 MBCH RELAY bias differential 25 27 26 28 Overcurrent test set start timer stop timer 1 3 2 4 Figure 2 Connections for checking relay operating time Figure 1 Connections for checking relay settings ...

Page 31: ...for checking the bias curve A1 A2 ac supply 1st bias 2nd bias 3rd bias 4th bias 5th bias 6th bias 15 16 17 18 19 20 21 22 23 24 25 26 27 28 Variable Auto transformer Differential coil 0 100Ω MBCH 16 ONLY MBCH 13 16 ONLY 0 100Ω ...

Page 32: ...32 0 5 1 0 1 5 2 0 2 5 3 0 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 0 0 Is 0 5 In 0 4 In 0 3 In 0 2 In 0 1 In Mean bias current Amps x In Differential current Amps x In Figure 4 MBCH 12 13 16 bias curve ...

Page 33: ...33 Figure 5 Connections to the relay to simulate magnetizing inrush current waveform MBCH RELAY bias differential 25 27 26 28 A ac supply variable auto transformer 0 100Ω S2 S1 ...

Page 34: ...34 Figure 6 Mesh busbar arrangement requiring three bias inputs to the differential relay 87 Bias inputs Relay Type MBCH13 Operating Circuit ...

Page 35: ...35 Figure 7 Three winding transformer one power source 87 Bias winding Operating Circuit Relay type MBCH 12 Sole infeed Loads ...

Page 36: ...36 Figure 8 Switchgear arrangement where six bias inputs may be required 87 Bias Windings Relay Type MBCH 16 Operating circuit ...

Page 37: ...8 23 25 27 27 24 26 28 300 5 A 262 4 A 66kV 11kV 30 MVA 1574 6 A 1800 2 89 A 4 374 A N E R 4 374 A Relay Type MBCH12 Bias Windings Operating circuit 24 26 28 Figure 9 Example of a 30 MVA transformer with current flow indicated ...

Page 38: ... S2 S3 S4 P1 P2 Output to Relay Note Winding Separation on terminal nos 6 not available on earlier models Primary winding energized from live cts via terminals P1 and P2 Figure 10 Disposition of windings on matching transformer ...

Page 39: ...Two winding transformer with unmatched line current transformers 1574 6 A 1600 1A 11kV 66kV 300 1A 30 MVA 0 875 0 875 A 0 984 A Ratio 262 43 A Differential Relay MBCH12 0 984 S1 S4 0 887 tap ie P1 P2 2 6 link S2 S3 ...

Page 40: ...25 27 28 26 21 22 23 24 25 27 28 26 21 22 23 24 25 27 28 26 MBCH 13 5000 5 A 1200 5 A 500 5 A 500 kV 13 45 kV 138 kV 400 MVA 100 MVA 300 MVA MBCH 13 MBCH 13 Figure 12 Three winding transformer showing interposing CTs ...

Page 41: ... 26 27 28 Module terminal block viewed from rear Case earth Input circuits Reset Bias see Note 2 Trip other phases V x Trip output Alarm See following sheets 2 1 2 Terminal 12 on each phase assembly should be interconnected by a screened lead GJ0153 001 with the screen connected to terminal 14 Notes 1 a CT shorting links make before b and c disconnect b Short terminals break before c c Long termin...

Page 42: ... 24 25 26 27 28 Module terminal block viewed from rear Case earth Input circuits Reset Bias see Note 2 Trip other phases V x Trip output Alarm See following sheets 3 2 1 2 Terminal 12 on each phase assembly should be interconnected by a screened lead GJ0153 001 with the screen connected to terminal 14 Notes 1 a CT shorting links make before b and c disconnect b Short terminals break before c c Lon...

Page 43: ... 17 18 19 20 21 22 23 24 25 26 27 28 Module terminal block viewed from rear Case earth Input circuits Input circuits Reset Trip other phases V x Trip output Alarm See following sheets 6 5 4 3 2 1 See following sheets DIFF 2 Terminal 12 on each phase assembly should be interconnected by a screened lead GJ0153 001 with the screen connected to terminal 14 Notes 1 a CT shorting links make before b and...

Page 44: ...rcuit breakers Phase A All output contacts shown are instantaneously initiated for any internal fault condition when terminals No 10 on each phase unit are connected together as shown Correct phase indication is maintained 1 3 5 2 4 6 Phase B 1 3 5 2 4 6 Phase C 1 3 5 2 4 6 10 14 13 10 14 13 10 14 13 Vx ...

Page 45: ...elay settings Is Phase A Phase B Phase C 0 1 x In __________ __________ __________ A 0 2 x In __________ __________ __________ A 0 3 x In __________ __________ __________ A 0 4 x In __________ __________ __________ A 0 5 x In __________ __________ __________ A Check trip contacts operate __________ __________ __________ A Check alarm contact operates __________ __________ __________ A 3 2 4 Operat...

Page 46: ...2 8 On load tests Load conditions Measured differential current __________ __________ __________ A 3 2 9 Magnetizing current inrush test _________________________________________ _________________________________ __________________________________ Commissioning Engineer Customer Witness _________________________________ __________________________________ Date Date ...

Page 47: ...______ Main CT Test set Frequency _____________ 2 Which type of test was being used ____________________________________________ 3 Were all the external components fitted where required Yes No Delete as appropriate 4 List the relay settings being used ____________________________________________________________________________ _______________________________________________________________________...

Page 48: ...te By how long ___________ 8 What indications if any did the relay show ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ 9 Was there any visual damage ___________________________________________________________________...

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