Rapid Diagnostic Method of Stator Ground Fault Caused by a Faulty Terminal Capacitor

It is difficult to diagnose the stator ground fault caused by a faulty terminal capacitor with the help of detecting insulation resistance.The corresponding mechanism is analyzed first based on the equivalent circuit of stator ground fault.Three-phase reference composed of stator voltages is adopted to make a comparative analysis on the phase characteristics of zero sequence voltage,which can be used to discriminate the stator ground fault caused by a faulty terminal capacitor or grounding transient resistance.And a practical method is proposed based on the foregoing characteristics.In this approach,the position of zero sequence voltage in the three-phase reference can be judged by voltage waveforms from the wave-recording device.Furthermore,the winding capacitance to ground and grounding resistance of the neutral point should be utilized to realize rapid diagnosis.Finally,the effectiveness of the proposed approach is verified through a relevant fault example.