A possible mechanism for neutral grounding resistor failures

The authors have found a mechanism that may account for recent failures of neutral grounding resistors in 26 kV substations owned by Public Service Electric and Gas Company (PSE&G). A neutral grounding resistor can fail due to a local, high-frequency oscillation involving the inherent inductance of the resistor and the transformer phase-to-neutral coupling capacitance. High voltages within the neutral resistor structure can be developed by the cable ring-down transients initiated by a single-line-to-ground fault on a 26 kV feeder circuit. This failure mechanism has not been previously reported in literature.