Study on Failure Mechanism of Oil Paper Insulation under Partial Discharge of Bubble Defects

Partial discharge (PD) seriously affects the safe operation of power transformer. Studying the influence of PD in internal bubble of oil paper insulation and understanding the insulation failure mechanism can provide guidance for engineering practice. In this paper, the induction mechanism of PD on insulation failure is obtained by analyzing the short-time breakdown characteristics of oil paper insulation with different bubble parameters. Through the comparative analysis of bubble area and PD parameters, a positive feedback model for the insulation degradation is obtained, representing that bubble defects will deteriorate rapidly in exponential form under the effect of PD. Finally, with the help of electron microscope and energy spectrum analysis, the deterioration process of insulating paper is divided into four stages, obtaining the micro deterioration and failure mechanism of insulating paper.