Statistical Significance of Test Methods for Low Probability Breakdown and Withstand Voltages

A systematic evaluation of the statistical significance of different test methods currently used for the determination of the breakdown and withstand voltages was made. The breakdown probability of the test voltages was evaluated by both direct calculation and computer simulation of the test methods, assuming a known intrinsic breakdown probability in a single voltage application (or one cycle ac). The latter was assumed to be of either normal, smallest values or Weibull type, and to be unaffected by the event occurring in the pre- ceding voltage applications (or ac cycles).