Application of arc breaking simulation in development of extra high voltage SF6 circuit breaker

During the short-circuit current breaking of the ultra-high voltage SF₆ circuit breaker, it needs to withstand a very high transient recovery voltage after the current zero time, which requires the interrupter to have a very strong breaking capacity. In this paper, the arc simulation method is used to simulate the L90 test process of the SF₆ circuit breaker design prototype, and the pressure, temperature and Mach number distributions of the interrupter at the current zero time are obtained. The study found that there is a shock wave in front of the static arc contact inside the nozzle, which causes high-temperature gas to be dissipated between the fractures, which may cause the failure of the interruption. According to the simulation results and design experience, an improvement proposal for the arc extinguishing chamber is proposed for this design structure defect, and the simulation calculation is used to verify it. The calculation results show that the improved interrupter scheme has no shock wave at the front end of the static arc contact, and the improved scheme has achieved the expected results, providing support for subsequent type tests.