Influence of arcing conditions on post-arc dielectric strength recovery of VCB—Simulation based on an improved CTM

For vacuum circuit breaker (VCB), the contact surface temperature is still high after high current arcing, evaporation of metal vapor continues with considerable rates. The metal vapor and residual charge at current zero, i.e., the arc memory which depends on arcing conditions, determines the post-arc dielectric strength recovery of VCB. Considering the well-known continuous transition model (CTM) proposed by Andrews and Varey only shows the effect of residual charge on dielectric strength during sheath expanding period, thus, a submodel including metal vapor density and breakdown criteria corresponding to Paschen limit is added to the existing CTM. Moreover, it has taken into account the charge exchange between ions and vapor atoms. Its accuracy is verified by comparing simulation result with test and the other simulation data. Then based on the improved CTM, influence of arcing conditions including arcing time t₀, interrupted current amplitude i_p and ramp di/dt on the post-arc dielectric strength recovery of VCB are simulated and analyzed.