Over-voltage protection relay NC20

under-voltageunder-currenttrip circuit

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 According to the hardware configurations, the NC20 protectionrelay can be shipped in various case styles depending on therequired mounting options (flush, projecting mounting, rack orwith separate operator panel). Six output relays are available (two changeover, three make andone break contacts); each relay may be individually programmedas normal state (normally energized, de-energized or pulse) andreset mode (manual or automatic).A programmable timer is provided for each relay (minimum pulsewidth). The user may program the function of each relay according to a matrix (tripping matrix) structure.