Breakdown and Flashover Characteristics for Discharge via Floating Electrode and Solid Insulator in Vacuum

We focus on the discharge process via both the shield (floating electrode) and the solid insulator in vacuum interrupters. We proposed an electrode configuration in vacuum chamber (10-5 Pa) for investigating discharge via the shield and the solid insulator. The electrode configuration consists of cathode-shield-insulator-anode(c-s-i-a), and we carried out the discharge experiments using a negative standard lightning impulse voltage (1.2/50 µs). We measured the shield potential by a high voltage probe, the anode current by a high frequency current transformer, and the light intensity by a photomultiplier tube, respectively. As the results, the discharge in c-s-i-a configuration can be classified into two independent processes: one is the discharge between cathode and shield (c-s), and the…