Interruption life of vacuum circuit breakers

Over the past few years, there has been an increased interest in the number of short circuit interruptions a vacuum circuit breaker is capable of before excessive wear occurs on the contacts. Several methods have been proposed for recording or extrapolating the interruption life of vacuum circuit breaker contacts and these have resulted in many different claims. As a means of reconciling these, and for providing a common ground for axial magnetic type vacuum circuit breaker contacts, a recommendation is made for a new means of measuring contact life. This new method is based on the interruption level and the amount of time in which the arcing between the contacts occurs. This is then compared against test results for vacuum circuit breaker contacts from Cooper Power Systems.