Prestrike Characteristics of Double-Break Vacuum Circuit Breakers with Asynchronous closing operations under DC Voltages

The prestrike phenomenon in double-break vacuum circuit breakers (VCBs) is complex but significative. Previous studies mainly focused on the prestrike phenomenon in double-break VCBs with synchronous closing operations. However, experimental work on prestrike characteristics of double-break VCBs with asynchronous closing operations cannot be found in literature. This paper aims to experimentally investigate the probabilistic characteristics of prestrike gaps and prestrike voltage distributions in double-break VCBs consisting of two commercial vacuum interrupters (VIs) in series with asynchronous closing operations under direct current (DC) voltages. Four groups of closing operation tests are carried out, including the synchronous closing operation of two VIs, 1ms faster of the low-voltage side VI, 0.5ms faster of the high-voltage side VI, and 0.2ms faster of the high-voltage side VI. The experimental results show that the 50% prestrike gap d
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and the 50% prestrike voltage U
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of each VI in double-break VCBs, which is calculated by the Weibull distribution. Scatters in prestrike gaps of each VI in the double-break VCB in the case of 0.2ms faster of the high-voltage side VI are smaller than that in the case of synchronous closing operations because of the voltage-sharing effect in the double-break VCB. The Weibull distributions of prestrike voltage under different conditions show that asynchronous breakdown of double-break VCBs has the effect of changing the partial voltage ratio of double break.