Abstract
We have studied interrupting phenomena with alternative gasses to SF6, especially N2-SF6 gas mixture. This paper describes capacitive current switching phenomena and performance of the gas mixture. Capacitive current switching tests were performed with N2-SF6 gas mixture, N2 and SF6 in a 300kV class gas circuit breaker. Dielectric recovery characteristics have been calculated by combining breakdown field strength data with gas flow calculations and electric field calculations. Comparing both results, the influence of dielectric synergism and gas flow of the gas mixture on the performance is discussed. As a result it is found that capacitive current switching performance of N2(85%)-SF6(15%) gas mixture is almost80% of that of pure SF6. Consequently it will be possible to realize full performance with gas mixture by improvement of GCB design.
