AQ-T257 Transformer Protection IED

AQ-T257 is a transformer protection IED with differential protection function and integrated AVR function. The AQ-T257 transformer protection IED provides also for complete current and voltage based protection functions and full measurements. Up to 9 optional I/O or communication cards are available for extensive monitoring and control applications. The AQ-T257 communicates using various protocols including IEC 61850 substation communication standard.

Highlight

  • Large I/O capability 2nd and 5th harmonic blocking
  • Automatic / manual voltage regulating (AVR)
  • Complete transformer protection
  • 2nd and 5th harmonic blocking
  • Automatic verification of connection group and nominal value settings
  • Through fault and overloading statistics for preventive maintenance
  • Up to class 0.2S power and energy measuring
Protection
2 winding transformer differential (87T)
High/low impedance restricted earth fault / cable end differential * (87N1, 87N2)
Transformer thermal overload (49T/49RTD)
Three-phase overcurrent, 2+2 stages INST, DT or IDMT (50/51)
Earth-fault (sensitive), 3 stages INST, DT or IDMT (50/51N)
Harmonic overcurrent / inrush blocking, 4 stages INST, DT or IDMT (50/51H, 68)
Current unbalance / broken conductor, 2+2 stages INST, DT or IDMT (46/46R/46L)
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)
Volts per hertz (24)
Breaker failure protection (50BF/52BF)
Arc protection (option) (50ARC/50NARC)