Investigation of the analysis methods for intermittent arc grounding overvoltage

There are two different analysis methods about overvoltage generated by intermittent arc grounding in the insulated neutral system: arc extinction theory based on power frequency and high frequency. The overvoltage can not endanger the safe operation of equipments because it is only 3.5p.u. according to the power frequency arc extinction theory. But overvoltage is 7.5p.u. as a result of the high frequency arc extinction theory which inevitably leads to the system faults. According to the investigation of two arc grounding faults (two phase grounding fault of a 10 kV bus and C-phase grounding fault of a 10 kV oil-minimum breaker), the validity of the arc extinction theory based on high frequency was proved.