A statistical aging model for paper oil insulation under repetitive transients

AC voltage has been applied on oil impregnated paper with superimposed transients of repetition frequency ranging from 1 kHz to 10 kHz. The time-to-breakdown has been recorded. Then the “accelerated life test analysis” (ALTA) approach is applied to model the lifetime vs. repetition frequency relationship with inverse power, Eyring or exponential laws. During the “accelerated life test analysis”, the recorded life data at multiple repetition frequencies can be inputted simultaneously into the statistical aging model, and the parameters of each life vs. frequency relationship can be estimated. The estimation shows that the inverse power, Eyring or exponential relationships can be applied in our test frequency ranges, and extrapolated to higher or lower frequencies.