Partial Discharge Characteristics of Void Defect in SF6 under Stepped AC Voltage

This paper investigates the partial discharge characteristics of void defect in SF6 gas insulation under stepped alternating current voltage. Two kinds of partial discharge detection techniques are used, e.g. phase-resolved partial discharge pattern and current pulse waveform analysis. The partial discharge patterns and current pulse waveform are obtained by using a commercial partial discharge measurement system and oscilloscope, respectively. With the applied voltage raised in a regular step, the patterns of partial discharges were recorded. From the results of phase-resolved partial discharge (PRPD) patterns and some deduced histograms, statistical operators like as skewness and kurtosis were calculated, and used to investigate the partial discharge characteristics. After that, the statistical signature (fingerprint) information representing the insulation condition were extracted from the experimental results. The partial discharge characteristic from different alternating current applied voltage indicates that phase-resolved partial discharge patterns and current pulse waveform (CPWA) vary with applied voltage. The partial discharge evolution was analyzed using single current pulse waveform and sequential current pulse waveform.