Measurement of Electrode Surface Temperature and Post-Arc Current in Vacuum Interrupter

In vacuum interrupters, plasma remains between the electrodes after the current zero because of arcs generated by the interruption of short-circuit current. This residual plasma consisting of ions, electrons, and metal vapor affects the insulation recovery process after the short-circuit current interruption. The ion and electron densities can be attributed to the post-arc current and the electrode surface temperature. Therefore, direct measurement of the post-arc current and electrode surface temperature is crucial for a fundamental understanding of the insulation recovery process after the short-circuit current interruption. In this study, a prototype spiral electrode was mounted in a vacuum chamber, and the electrode surface temperature and the post-arc current were measured. The electrode was made of Cu-Cr material, and the interruption current above 10–24 kArms was applied. The electrode surface temperature was measured two-dimensionally using a two-color pyrometer method. The melting area increased with an increase in the interruption current above 20 kArms. The post-arc current and its charge also increased with increasing the interruption current, but they did not increase as dramatically as the melting area.