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NC20 - Manual - 01 - 2015
Oscillography (DFR) .................................................................................................................................................................................... 23
PLC (Programmable Logic Controller) ......................................................................................................................................................24
Metering inputs ............................................................................................................................................................................................ 29
Signal processing ......................................................................................................................................................................................... 29
Conventions ................................................................................................................................................................................................... 33
Use of measured values ...............................................................................................................................................................................34
Binary inputs ..................................................................................................................................................................................................35
Output relays ................................................................................................................................................................................................. 40
LED indicators ................................................................................................................................................................................................42
Communication interfaces ...........................................................................................................................................................................44
Undervoltage - 27 ......................................................................................................................................................................................... 50
Undercurrent - 37 ..........................................................................................................................................................................................54
Phase unbalance current - 46 .....................................................................................................................................................................57
Neutral unbalance current - 46N ............................................................................................................................................................... 63
Phase overcurrent - 50/51 RMS ..................................................................................................................................................................82
Phase overcurrent - 50/51 Fundamental .................................................................................................................................................. 89
Residual overcurrent - 50N/51N .................................................................................................................................................................96
Overvoltage - 59 ...........................................................................................................................................................................................106
Breaker failure - BF .................................................................................................................................................................................... 110
Logical block - BLOCK1 ..............................................................................................................................................................................112
Selective block -BLOCK2 ...........................................................................................................................................................................114
Remote tripping .......................................................................................................................................................................................... 119
Frequency tracking .................................................................................................................................................................................... 120
Cold Load Pickup - CLP ..............................................................................................................................................................................121
CT supervision - 74CT .................................................................................................................................................................................122
Circuit breaker supervision .......................................................................................................................................................................126
Demand measures ..................................................................................................................................................................................... 129
Oscillography ............................................................................................................................................................................................. 129
5 MEASURES, LOGIC STATES AND COUNTERS
Measures ..................................................................................................................................................................................................... 130
Protection .................................................................................................................................................................................................... 130
Delayed inputs ............................................................................................................................................................................................ 130
Internal states ............................................................................................................................................................................................. 130
Relays ............................................................................................................................................................................................................131
Counters ........................................................................................................................................................................................................131
Self test .........................................................................................................................................................................................................131
Pilot wire diagnostic ...................................................................................................................................................................................132
Selective Block - BLOCK2 ..........................................................................................................................................................................132
Fault recording - SFR ..................................................................................................................................................................................132
Event recording - SER ................................................................................................................................................................................ 133
Oscillography - DFR ................................................................................................................................................................................... 133