Study on the Influence of Impurities on Partial Discharge and Flashover Characteristics of Pressboard Based on Three-parameter Weibull Model

The failure rate of converter transformers is high, mainly caused by impurities on the surface or inside the insulation material. In this paper, two electrodes are designed based on impurities at different positions, and three-parameter Weibull distribution is proposed to describe the distribution characteristics of discharge voltage. The results show that the discharge caused by internal and surface impurities of insulating pressboard has obvious size effects, and metal impurities have a greater influence on the discharge voltage. Compared with internal impurities, surface impurities are more harmful to insulation.