Abstract:

Taking SF₆ and SF₆/N₂ gas mixture as the research object,the arc model under the condition of AC power supply,single nozzle and fixed electrode is established.The post arc thermal breakdown characteristics of substitute gas circuit breakers are studied by combining Mayr arc model.The Boltzmann equation is solved by using the two-term approximation method,and the critical breakdown field strength of mixed gas is calculated and compared with the actual field strength of the substitute gas circuit breaker model.The results show that when the SF₆ content in the SF₆/N₂ mixed gas is high,the performance of the post arc breakdown characteristics is close to that of the pure SF₆ gas circuit breaker.It basically has the post arc breakdown characteristics of SF₆ gas and can realize the replacement of SF₆ gas,which provides the theoretical basis for the research and development of SF₆ substitute gas circuit breaker,and has reference value for the research on the re-breakdown problem of the substitute gas circuit breaker.

Key words: SF₆/N₂ gas mixture, thermal breakdown, electric breakdown, arc model, critical breakdown field strength