Simulation of Arc Breaking in a 550 kV 80 kA SF6 Circuit Breaker

As the structure of power grid becomes increasingly complex and the capacity keeps increasing, the short-circuit current endurance of existing switching devices can no longer meet the needs of the development of power grid. The rated short-circuit current of 550 kV circuit breakers needs to be increased from 63 to 80 kA, which puts forward more stringent requirements on the breaking capacity of circuit breakers. In this paper, based on the magnetohydrodynamic model of arc burning in the arc extinguishing chamber of the circuit breaker, a 550 kV SF6 auto-expansion circuit breaker was simulated for 9 ms under the working condition of 80 kA short-circuit current breaking. The distribution of temperature field, pressure field and electromagnetic field in the arc extinguishing chamber during the breaking process was obtained, together with the characteristic of the hot flow field. Through the comprehensive analysis of temperature field, pressure field and boundary conditions, this paper describes the arc burning process of circuit breaker in the arc extinguishing chamber, and accurately analyzes the physical process of circuit breaker when it breaks off, which provides some reference value for the optimization design of circuit breaker structure.