Partial Discharge Degradation Analysis from Light Emission Observation and Partial Discharge Characteristic Measurement by Partial Discharge in Artificial Defects using Transparent Electrodes

Changes in the q-Φ-n distribution of partial discharge (PD) generated by a simulated defect structure have conventionally been investigated to determine the degree of partial discharge degradation of resin or resin composite materials due to long-term application of voltage. The purpose of this study is to analyze the relationship between the change in the q-Φ-n distribution and of that in the discharge state occurring inside the defect. A spherical electrode/ polyethyleneterephthalate (PET)/ cylindrical void/ PET/flat plate electrode system was employed as an artificial defect structure, and an Indium tin oxide (ITO) transparent electrode was used as a flat plate electrode to enable direct observation of the light emissions during the occurrence of partial discharge. The observations of changes in the q-Φ-n distribution and the discharge state occurring inside the defects are presented in this paper. Furthermore, the mechanism of resin degradation is discussed based on the observation results of resin surfaces exposed to partial discharge for a long term. We found that the degradation of PET surface progressed faster when the PD was sustained at the protruding structure, which is a PD byproduct.