Influence of Barrier along Insulator Surface on Current Characteristics in Vacuum Surface Discharge under Standard Lightning Impulse Voltage Application

In a vacuum circuit breaker, vacuum surface discharge may occur along the insulator surface inside the vacuum interrupter (VI) when high voltage is applied. It is thought that this surface discharge in vacuum can be suppressed by installing a barrier. In this paper, the voltage and current waveforms of vacuum surface discharge were measured, which generated by applying a negative standard lightning impulse voltage to a cylindrical insulator which resembles the VI. The voltage and current waveforms measured were compared in cases with and without a barrier installed on the insulator surface in vacuum. The result shows the flashover voltage was higher with the barrier compared to without the barrier. When the barrier was placed closer to the cathode, the flashover voltage became even higher.