Influence of short-circuit current on motion characteristics of valves during breaking process of high-voltage auto-expansion SF₆ circuit breaker

The motion characteristics of non-return valve has a direct influence on the accuracy of simulation result of high-voltage auto-expansion SF₆ circuit breaker. To this end, we built a magnetohydrodynamic simulation model coupled with action of valves for high-voltage auto-expansion SF₆ circuit breakers. Then we researched the arcing characteristics under two typical breaking conditions with short-circuit current of 36 kA and 40 kA and arcing time of 15.3 ms. The temperature and pressure distribution, the ablation mass of nozzle and the motion characteristics of non-return valve were analyzed. The results show that, compared with the case of 36 kA, the temperature and pressure in 40 kA case all increase, the non-return valve acts earlier by 0.8 ms, and the ablation mass increases by 0.35 g.