Influence of fault parameters on breaking performance of vacuum circuit breaker

In order to analyze the influence of power system fault parameters on the breaking performance of vacuum circuit breaker (VCB), a black box model of VCB based on the diffuse vacuum arc interruption has been established in this paper. Taking the current zero as the demarcation point, arc voltage is modeled during the arcing period and post arc current (PAC) is modeled based on the theory of Langmuir probes during the post arc period. Based on this model, the equivalent discount factor of the breaking capability of VCB caused by the direct current (DC) component of short circuit current is evaluated using different methods. In addition, the post arc conductivity is used to represent the dielectric strength recovery of VCB, and the results show that the rate of rise of transient recovery voltage (TRV) mainly influences the post arc dielectric recovery rate after 1.5 μs, while the rate of decrease of short circuit current prior to current zero only influences the initial post arc dielectric recovery rate. This model is expected to provide an effective way to predict the breaking performance of VCB.