Influence of Outlet Configuration on Arc Stagnation Phenomenon in Miniature Circuit Breaker

During the breaking process of a circuit breaker, an arc is generated. The arc is extinguished by the splitter plates inside the arc chamber. When the arc moves toward the splitter plates, some obstruction may lead to arc stagnation, which in turn negatively affects the arc extinguishing. The objective of this paper is to determine the influence of outlet configuration on arc stagnation phenomenon. A simplified arc chamber model for miniature circuit breakers was established based on the principles of magnetohydrodynamics (MHD), to simulate the arc motion characteristic. The results show that, in the arc chamber with a single air outlet, a vortex forms near the upper arc runner. This causes the arc root to stagnate, resulting in only part of the arc entering the splitter plates and the arc-extinguishing performance is adversely affected. The additional air outlet promotes upward airflow, which weakens the influence of vortices on arc root movement, reduces heat accumulation caused by arc root stagnation. This ultimately promotes arc extinction.