AQ-G257 Generator Protection IED

The AQ-G257 generator protection IED is well suited for large machines requiring complete generator protection and differential protection. Up to 9 optional I/O or communication cards are available for extensive monitoring and control applications. Up to 16 RTD signals can be connected for thermal alarming and tripping. The AQ-G257 communicates using various protocols including IEC 61850 substation communication standard.

Highlights

  • Complete synchronous machine protection
  • Integrated differential protection
  • Power measurements up to class 0.2S
Protection
Generator/transformer differential (87G/T)
Three-phase overcurrent, 2 stages INST, DT or IDMT (50/51)
Earth-fault (sensitive), 2 stages INST, DT or IDMT (50/51N)
Harmonic overcurrent / inrush blocking, 4 stages INST,DT or IDMT (50/51H68)
Current unbalance / broken conductor, 2 stages INST, DT or IDMT (46/46R/46L)
High/low impedance restricted earth fault / cable end differential * (87N)
Directional overcurrent, 4 stages INST, DT or IDMT (67)
Directional (sensitive) earth-fault, 4 stages INST, DT or IDMT (67N)
Overvoltage, 2 stages INST, DT or IDMT (59)
Undervoltage, 2 stages INST, DT or IDMT (27)
Zero sequence overvoltage, 2 stages INST, DT or IDMT (59N)
Positive/Negative sequence overvoltage, 2 stages INST, DT or IDMT (59N/47)
Over/under frequency, 4 stages INST or DT (81O/81U)
Rate of change of frequency, 4 stages INST or DT or IDMT (81R)
Loss of field (40)
Voltage restrained overcurrent (51V)
Field ground / 100% stator earth-fault (64S)
Rotor earth-fault protection (64R)
Over/Under/Reverse power (32/37/32R)
Generator thermal overload (49G/49RTD)
Under impedance (21U)
Volts per hertz (24)
Out of step / pole slip (78)
Breaker failure protection (50BF/52BF)
Arc protection (option) (50ARC/50NARC)