Phase dependence of partial discharge current pulse waveform and its frequency characteristics in SF6 gas

The authors performed time-resolved partial discharge (PD) measurements in SF₆ gas for a needle-plane arrangement to investigate the frequency of PD current pulses. The experimental results revealed that the PD pulse waveform differed depending on the phase angle even when the magnitude of applied voltage and gas pressure were constant. This means that the frequency component of PD pulses differed depending on the polarity and the phase of applied AC voltage. Consequently, they pointed out the necessity to select an appropriate PD-measuring frequency range with the frequency component of PD pulse considered