Dielectric strength and statistical property of single and triple-break vacuum interrupters in series

The maximum possible improvement factor of vacuum circuit breaker (VCB) with multiple breaks compared with one-break, which had the same total gap length, was deduced. Based on the research on the breakdown weak points in high voltage vacuum gaps, a theoretic model was set up for describing the statistical property of multi-break VCB. Dielectric experiments were carried out on a commercial vacuum interrupter arrangements with single break or triple breaks in series under lightning impulse voltage. It shows that the more numbers in series are, the higher the breakdown voltage improvement factor is. The statistical results show that the triple-break vacuum interrupters in series have lower breakdown probability compared with a single-break one. It can be demonstrated in a preliminary study that the experimental results confirm the previous theoretical studies.