Influence of Switching Frequency on Breaking Characteristics of DC Vacuum Circuit Breaker

The dielectric recovery of DC vacuum circuit breaker (VCB), involving the 1^st "preparation", 2^nd development and 3^rd metal-vapor attenuation stages in sheath growth, was mathematically formulated with continuous transition model, theoretically analyzed and numerically simulated.To begin with, the duration of the 1^st-stage was calculated; next, the influence of the current frequency/amplitude in the 2^nd-stage on the dielectric recovery was investigated via simulation and the results show that the limiting breaking current decreases with an increase of the frequency; and finally, the intermediate frequency breaking capacity of VCB was evaluated and the dependence of the limiting DC breaking current on the commutation frequency was obtained.