Fundamental Study for Quantification of Change in PD Waveform on Electrical Treeing

Partial discharge (PD) measurement has been used as a test to evaluate the insulation systems and as a quality control test for the new power equipment. A continuous generation of PDs will decrease the insulation performance and lead to the dielectric breakdown. Many researches related to the PDs detection and diagnosis of the degradation by PDs were conducted. The occurrence time (phase) or the charge amount has been investigated as the parameters representing PD characteristics. However, the PD waveforms itself represents the processes such as the formation of electron avalanches and sweep out of ions. In this paper, a device which can acquire all PD waveforms was constructed and we also demonstrated the utility of the measurement system by analyzing the changes in characteristics of PD waveforms. In addition, the difference between waveforms with PD generated in air and inside electrical tree tubes was presented.