Research on post-arc reignition phenomena for 40.5kV vacuum interrupter

When interrupting capacitors or short circuit fault by a vacuum circuit breaker, post-arc reignition occurs frequently resulting in a high overvoltage and even interruption failure. In order to research reignition phenomena, this paper proposed a synthetic circuit which can apply a DC recovery voltage after current zero for a long period. Through plenty of experiments, reignition characteristics of 40.5kV commercial vacuum interrupters are measured. Some factors including interrupting current, electrode separation and structure which may affect reignition characteristics are studied. For simulating capacitor switching or short circuit interruption, a arcing specific current value is interrupted (400A, 630A, 800A for capacitors and 6.3kA, 12.5kA, 16kA, 20kA, 25kA for short circuit). Under various electrode separations, the statistical probability of reignition is obtained. As a result, the best scope of electrode separation is put forward, in which the probability of reignition is lower and post-arc withstand voltage is higher. For 40.5kV commercial vacuum interrupter, this range is from 15mm to 18mm.. Furthermore, it is found that after some interruption at a specific current value, a full conditioning effect is reached and the probability of reignition decreases obviously.