Partial Discharge Characteristics of the Metal-Insulation Interface Under Repetitive Microsecond Pulse Voltage

This study investigates the discharge characteristics of the metal-insulation interface under repetitive frequency pulse voltage by examining partial discharge, which commonly arises from unavoidable manufacturing defects at this interface. Three test configurations with varying electrode-dielectric gaps were devised and fabricated. The focus of the study was to analyze the characteristics and development process of partial discharge under repetitive frequency pulse voltage, as well as to explore the relationship between partial discharge and lifespan. A comparative analysis of the partial discharge characteristics among the three different configurations was conducted. Simulation calculations were performed to evaluate the instantaneous local temperature rise caused by partial discharge, revealing that the high temperature and high pressure generated during discharge play critical roles in film breakdown. Additionally, the study examined the trend of the first discharge voltage concerning the number of applied pulses in different configurations. The results indicated that in air-filled gaps, the first discharge voltage exhibited a trend of increase-decrease-increase, with the relationship between the maximum rise rate of the first discharge voltage in the early stage and the sample life following a power relationship characterized by a power exponent of -0.92. In the oil-gap configuration, the process of oil gap discharge generating bubbles and subsequent discharge within these bubbles resulted in a significant drop in the first discharge voltage. Furthermore, a negative power relationship was established between the decrease rate of the first discharge voltage and the remaining life in this configuration.