Vacuum interrupter performance on abnormal voltage/current tests

Vacuum interrupters, as applied to high-voltage power-class circuit breakers, are capable of providing exceptional performance. However, they do have operational limits as well as a finite life. Inadvertently, they may be subjected to conditions beyond their capability. Some of the consequences of this overloading have been presented, with additional insight into reasons behind such behavior. The ability of the vacuum devices to fail to clear test circuits - and still be in usable condition after the fact - is unique in the power circuit breaker field. This is not a recommendation for the application of these devices under conditions beyond the design goals.