Statistical Property of Breakdown between Electrode and Shield in High-Voltage Vacuum Interrupter

Statistical property of the breakdown between stainless or copper electrode and stainless arc shield is studied by applying (250 × 2000)-¿s switching impulses to model vacuum interrupters. Higher breakdown voltages are obtained in negative polarity than in positive polarity. The effective area of breakdown which takes the electric-field distribution on the anode surface into account is introduced to explain the polarity effect of breakdown voltage using Weibull statistics.