Transient Arc Behavior Immediately after Electrodes Separation in Axial Magnetic Field Electrode for Vacuum Interrupter

In vacuum interrupters (VIs), vacuum arc behavior strongly affects interruption ability. To increase interruption ability of axial magnetic field (AMF) electrode by preventing local heating of the electrodes, to diffuse the arc widely at surface of electrodes is important. The arc immediately after electrodes separation is localized. This arc gradually diffuse and is eventually stabilized by the AMF. To increase interruption ability, it is important to diffuse the first arc quickly. In this paper the results of observations and analysis of the vacuum arc behavior immediately after electrodes separation are reported. Arc behavior was analyzed in chronological order during period between electrodes separation and current peak. As a result, the arc diffusion characteristics were clarified.