Partial Discharge Current Pulse Waveform Analysis (CPWA) for electrical insulation diagnosis of solid insulators in GIS

We developed a novel approach based on PD Current Pulse Waveform Analysis (CPWA) in order to estimate insulation degradation of solid insulators with different kind of defects. In the CPWA method we focused on the time transition of PD waveform parameters such as rise-time, fall-time, di/dt and peak value in a single PD current pulse waveform. PD current pulse waveform may include informations on physical phenomena from PD inception to BD. We fabricated epoxy spacer models with delamination as an insulation defect. The time transition of PD waveform parameters described above was measured and analyzed under a long-term ac voltage application. Using CPWA method together with statistical PD parameters such as PD charge, PD generation phase and frequency, we discussed the mechanism of insulation degradation process of the epoxy spacer for GIS from PD inception to BD.