The Electrode Surface State after Current Interruption in Vacuum Circuit Breaker

We have researched the factors of high insulation recovery characteristics after current interruption in vacuum circuit breakers (VCB). VCB have high insulation recovery characteristics because of diffusing metal vapor to surroundings by high diffusion effect of vacuum. However, when the arc current exceeded the certain value, electrode erosion was remarkable and insulation recovery characteristics decreased. In this paper, we measure anode surface temperature just after current zero with two-color pyrometer. And we observe the vacuum arc with high speed CCD camera. Contact material we used are Cu, CuCr, and AgWC. Test results were as follows. Melting duration of CuCr electrode was longer than that of the Cu electrode. We observed particles in vacuum arc in the case of Cu electrode and AgWC electrode, but we could not observe any particles in the case of CuCr electrode