Discussion and overvoltage analysis of NSDD in the capacitive current switching test of vacuum circuit-breaker

Vacuum circuit-breaker is an important electrical equipment for power system, and the switching capacitive current is its important performance test. In the switching capacitive current test, the vacuum circuit-breaker is easy to produce the situation of restrike and NSDD (non-sustained disruptive discharge). It is important to make the correct judgment about the occurrence of restrike and NSDD, because the results of the two decisions are very different. NSDD is a voltage breakdown after the vacuum circuit-breaker open the capacitive current which will not cause the recovery of power frequency or capacitive current. It’s not easy to show the distinction between NSDD and restrike during some type tests. Although the impact of NSDD on the vacuum circuit-breaker itself is not very large, the voltage change will have some influence on the insulation of the surrounding electrical equipment. The voltage drop will even affect the power quality of the power system. In this paper, combined with the type test of vacuum circuit-breaker switching capacitive current, the analysis of the above situation has carried on the summary, it has certain guiding significance to the effective judgment for happening to restrike and NSDD, at the same time, the paper analyses the voltage change of NSDD influence on power system equipment.