Analysis of Temperature Distribution and Ablation Gas Concentration Distribution under Consideration of Nozzle Ablation Caused by Spiral ARC Applied Axial Magnetic Field

The high speed and reliable current interruption are required as the needs for circuit breaker in order to minimize the damage of accident when the accident occurs in the power system. However, the global warming potential of SF6 used in GCB(Gas Circuit Breaker) is 22800 times higher than that of CO
2
, which imposes the heavy burden on the environment. Thus, improved ACB(Air Circuit Breaker) performance is demanded in order to reduce the burden on the environment. The polymer material is used for the nozzle of ACB. The polymer is ablated by the heat and radiation of arc. The arc is cooled by ablation gas because of the energy loss such as the dissociation. In addition, it has been reported that the arc resistance increases because the spiral arc is formed by applying the axial magnetic field in the process of decreasing the current. Therefore, the current interruption performance is able to be expected by focusing the ablation and spiral arc. In this paper, the temperature distribution and ablation gas concentration distribution under consideration of nozzle ablation caused by the spiral arc applied the axial magnetic field is elucidated. In this calculation, atmosphere gas is N2 and the ablation gas generated from nozzle is POM. The parameter of this calculation is axial magnetic field. In addition, the transient recovery voltage is applied in post arc in order to simulate the success of failure of the current interruption. This calculation dose not generate the ablation gas affected by the radiation transfer. As a result, the spiral arc was formed by the increasing axial magnetic field. On the other hand, the ablation gas generating position of nozzle changed because of changing the high temperature position of arc. In addition, the arc voltage increased owing to the spiral arc and the arc was locally cooled by the ablation gas. Therefore, the current interruption performance was improved considering both the ablation and axial magnetic field compared to only considering either one.