Evaluation of Insulation Tolerance Index of Epoxy Resin Under Square Wave Voltage

As the most important solid insulating material for high-frequency transformers, epoxy resin needs to withstand steep rising/falling edges (high dv/dt), high-frequency, multiharmonic square wave voltage, high temperature rise, vibration and other effects in the actual application process. Under the combined action of high-frequency electrical-thermal stress, the cumulative damage of the surface and interior of the epoxy resin accelerates the insulation failure, and significantly reduces the life of the high-frequency transformer. At present, there are few articles to study the life of epoxy insulation under square wave voltage, this paper refers to the test method of ACPE insulation voltage withstand index under DC voltage, and proposes a method to obtain the insulation life of epoxy by changing the voltage frequency, amplitude and temperature respectively, and then obtain the withstand index. The experimental results show that the voltage frequency and amplitude and insulation life meet the inverse power function curve well, and the relationship between temperature and insulation life has a tendency to decrease first and then increase. This paper provides an effective method to study the insulation life of epoxy resin under square wave voltage.