Behavior of Surface flashover Depending on Utilization in Vacuum Interrupters

Vacuum circuit breaker is one of the main power devices in distribution systems. Vacuum interrupter is one of the main parts of vacuum circuit breaker for breaking fault current. Surface flashover of the vacuum interrupter is one of the important factors to consider for high efficiency and compactness. In this paper, E field calculation and experiment were conducted to identify the influence of the shape of end shield. Three type models were used to analyze maximum E field of each model. Utilizations were calculated through E field results. For considering surface flashover of inner vacuum interrupter caused by end shield vacuum interrupters manufactured dummy model. It was installed only end shield. Test voltage was applied a positive lighting impulse. Measured results were analyzed through Weibull distribution. As a result, equation was proposed as a result of FEM analysis and experiment. It shows relation between calculated utilization and measured flashover inception voltage. It was expected application when designing end shield of inner vacuum interrupter.