IV 845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
Output Relays........................................................................................................................................4 - 127
Auxiliary Relay selected for breaker Trip..................................................................................4 - 130
Aux Relay selected for breaker Close.........................................................................................4 - 132
Auxiliary Output Relays ....................................................................................................................4 - 134
Critical Failure Relay #8....................................................................................................................4 - 135
Virtual Outputs ......................................................................................................................................4 - 136
Analog Outputs.....................................................................................................................................4 - 136
Protection....................................................................................................................................... 4 - 138
Percent Differential .............................................................................................................................4 - 140
Transformer Overload .......................................................................................................................4 - 151
Current Elements .................................................................................................................................4 - 153
Inverse Time Overcurrent Curves.................................................................................................4 - 153
Percent of Load-To-Trip....................................................................................................................4 - 160
Phase Time Overcurrent Protection (51P).................................................................................4 - 161
Phase Instantaneous Overcurrent Protection (50P) ............................................................4 - 164
Phase Directional Overcurrent Protection (67P)....................................................................4 - 166
Neutral Time Overcurrent Protection (51N).............................................................................4 - 169
Neutral Instantaneous Overcurrent Protection (50N).........................................................4 - 172
Neutral Directional Overcurrent Protection (67N) ................................................................4 - 175
Ground Time Overcurrent Protection (51G).............................................................................4 - 180
Ground Instantaneous Overcurrent Protection (50G).........................................................4 - 182
Ground Directional Overcurrent Protection (67G) ................................................................4 - 184
Restricted Ground (Earth) Fault (87G) .........................................................................................4 - 188
Negative Sequence Time Overcurrent Protection (51_2)..................................................4 - 193
Negative Sequence Instantaneous Overcurrent Protection (50_2)..............................4 - 195
Voltage Elements .................................................................................................................................4 - 198
Undervoltage Curves .........................................................................................................................4 - 199
Phase Undervoltage Protection (27P).........................................................................................4 - 200
Auxiliary Undervoltage (27X) ..........................................................................................................4 - 203
Phase Overvoltage Protection (59P)............................................................................................4 - 206
Auxiliary Overvoltage Protection (59X) ......................................................................................4 - 209
Neutral Overvoltage Protection (59N) ........................................................................................4 - 212
Negative Sequence Overvoltage Protection (59_2).............................................................4 - 215
Volts per Hertz (24) ..............................................................................................................................4 - 217
Power Elements....................................................................................................................................4 - 223
Directional Power (32)........................................................................................................................4 - 223
Frequency Elements...........................................................................................................................4 - 229
Underfrequency (81U) .......................................................................................................................4 - 229
Overfrequency (81O) ..........................................................................................................................4 - 232
Frequency Rate of Change (81R)..................................................................................................4 - 235
Monitoring...................................................................................................................................... 4 - 239
Transformer............................................................................................................................................4 - 239
Harmonic Derating..............................................................................................................................4 - 239
Thermal Elements................................................................................................................................4 - 242
Tap Changer Failure ...........................................................................................................................4 - 250
Trip and Close Circuit Monitoring .................................................................................................4 - 252
Breaker Arcing Current......................................................................................................................4 - 259
Breaker Health ......................................................................................................................................4 - 262
Functions .................................................................................................................................................4 - 266
Power Factor (55).................................................................................................................................4 - 266
Demand....................................................................................................................................................4 - 272
Pulsed Outputs......................................................................................................................................4 - 281
Digital Counters....................................................................................................................................4 - 284
Harmonic Detection ...........................................................................................................................4 - 287
RTD Temperature.................................................................................................................................4 - 290
RTD Trouble.............................................................................................................................................4 - 295
Loss of Communications..................................................................................................................4 - 296