DC Voltage Endurance of Capacitor BOPP Films at High Temperature

A large-area method for determining the voltage endurance of capacitor films is presented. The method was used to characterize the high field - high temperature performance of a commercial biaxially oriented polypropylene film. Following IEC standard 61251, an inverse power law model was fitted to the Weibull-distributed times-to-breakdown data. The insulation life increased rapidly as either field or temperature was decreased. Even at mildest stresses used, the failure rate was still increasing with time, implying that the conditions were above reasonable design limits. Determining the threshold conditions below which the failure rate starts to decrease with time may open up new paths for development of dielectric for higher energy density film capacitors.