Capacitor bank protection

The relay type NC20 provides protection of shunt capacitor banks and harmonic filter circuits. The capacitor banks may have the following configurations: Single Wye grounded. Single Wye ungrounded (with a resistor on the output of the neutral unbalance voltage transformer in order to develop the appropriate input current for the unbalance protection). Double Wye ungrounded. The capacitor banks may be: internally/externally fused or fuseless capacitor units. A suitable compensation method is provided to compensate the inherent unbalance neutral current Protections 37, 49 and 50/51 (RMS) are based on RMS value measurement of the three phase currents (fundamental and harmonics up to the 11th)


Standard Protective & control elements
  • Under Voltage
  • Under Current
  • Negative sequence overcurrent transformer
  • Phase overcurrent side H and side L
  • Maximum Residual Overcurrent
  • Overvoltage
  • Breaker Failure
  • CT Supervision
  • Trip Circuit Supervision
SW Pack optional configuration
  • Thermal with Pt100 Probes