AQ-M257 Motor Protection IED

The AQ-M257 offers a modular motor protection and control solution for larger and more important motors requiring 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-M257 communicates using various protocols including IEC 61850 substation communication standard.

Highlights

  • Differential protection
  • Large I/O capability
  • 5 time constant accurate thermal model
  • Softstart protection starting from 6Hz
  • Stardelta started motor supervision
  • 2 speed motor protection
  • Up to class 0.2S power and energy measurement
Protection
Motor differential (87M)
Three-phase overcurrent, 4 stages INST, DT or IDMT (50/51)
Earth-fault (sensitive), 4 stages INST, DT or IDMT (50/51N)
Directional overcurrent, 4 stages INST, DT or IDMT (67)
Directional (sensitive) earth-fault, 4 stages INST, DT or IDMT (67N)
Harmonic overcurrent / inrush blocking, 4 stages INST, DT or IDMT (50/51H, 68)
Current unbalance / broken conductor, 4 stages INST, DT or IDMT (46/46R/46L)
High/low impedance restricted earth fault / cable end differential (87N)
Motor thermal overload (49M)
Motor start-up / locked rotor supervision with speed switch (48, 14)
Restart inhibit / frequent starts (66/86)
Undercurrent/loss of load (37)
Power factor protection (55)
Mechanical jam (51M)
Overvoltage, 4 stages INST, DT or IDMT (59)
Undervoltage, 4 stages INST, DT or IDMT (27)
Zero sequence overvoltage, 4 stages INST, DT or IDMT (59N)
Negative/positive sequence overvoltage, 4 stages INST, DT or IDMT (47)
Over/under frequency, 8 stages INST or DT (81O/81U)
Over/Under/Reverse power (32/37/32R)
Breaker failure protection (50BF/52BF)
Arc protection (optional) (50ARC/50NARC)