Investigation on the high current interruption principle for series gaps of vacuum gap and CO2 gas gap

The current interruption capacity of gas gap can be enhanced by series connecting with vacuum gap in hybrid circuit breaker. For the purpose of compensating the inferior interruption performance of CO₂ gas gap, as the substitute for SF₆ gas gap, the interruption principle and the dielectric strength recovery process of the series gaps of vacuum gap and CO₂ gas gap are studied in this paper. Based on the established test prototype, tests are carried on series gaps to investigate the influences of various arcing times, voltage-dividing capacitor, and CO₂ gas pressure on its interruption performance via synthetic test circuit system. The test results convey that, CO₂ gas gap with gas pressure at 0.8 Mpa can recover its dielectric strength faster and withstand higher recovery voltage under the effect of voltage-dividing capacitor while vacuum gap undertakes initial transient recovery voltage. But limited by the simple structure of gas interrupter and the interruption performance of CO₂ gas, CO₂ gas can't recover its dielectric strength rapidly.