More Accurate Breakdown Voltage Estimation for the New Step-up Test Method for Various Probability Distribution Models

The step-up method is used to estimate the impulse breakdown voltageswhen the electrical insulation is not usable after it is broken. This paper analyses the reliability of the estimates of the underlying breakdown probability distribution inthe step-up method, when (1) the observed breakdown voltage itself is available and (2)it is not available. The former case has many advantages compared to the latter case such that (1) the confidence intervals of the estimates become smaller and (2) theestimates can be obtained in stable. This paper summarizes the results of the three cases that the underlying probability distribution for the breakdown voltage is assumedto be normal, Weibull, and gumbel types. The optimal test method is simply and clearlydescribed for various distribution models.