Evaluation of Partial Discharge Characteristics in Inclined Plane Tracking and Erosion Tests on Silicone Rubber under AC Voltage

Coastal and high pollution environments promote accelerated aging of polymer insulating materials due to electrical tracking and erosion. The inclined plane test (IPT), described in IEC standard 60587, has been a useful tool for ranking materials based on their resistance to tracking and erosion. Researchers have employed numerous analytical techniques, including statistical analysis of the leakage current, observations of dry band arcing characteristics, and thermal imaging, to identify the mechanisms that lead to material deterioration. In this paper, we present a study of partial discharge (PD) characteristics obtained during IPT measurements on high temperature vulcanized (HTV) silicone rubber under constant AC voltage stress. Two commercial PD measurement instruments are used to record magnitude in apparent charge, phase resolved PD (PRPD) plots, and individual pulse waveforms for analysis. PD recordings were synchronized with video recordings of visible discharges occurring on the HTV sample surfaces during test. Three types of visible discharge (arcing) phenomena were observed, leading to low, moderate and severe deterioration of the material respectively. It was found that each type of arc produces a distinct PRPD plot and its characteristic pulses form a separable cluster on the time-frequency map.