Transformer Insulation Reliability for Moving Oil with Weibull Analysis

To develop test conditions for a short-duration power-frequency withstand voltage test, which is one of the insulation specifications of substation equipment, the reliability can be precisely evaluated using a Weibull distribution function. This can be done by either the independence model or accumulation model, which have been proposed in order to handle the coexistence of multiple voltage levels, although the problem of how to use these models persists. This problem must be examined by comparing the results calculated by both models from the breakdown voltage-time characteristics and those involving the measurement of insulation characteristics obtained by applying voltages multiple times. The present study obtained the breakdown voltage-time characteristics of oil gaps by focusing on the presence of oil flows in oil-filled transformers as a parameter influencing the voltage application history. These test results, which will be the basic data for future study, are reported.