Modeling and numerical simulation of anode activity and arc motion in a transverse magnetic field

Vacuum interrupters based on transverse magnetic field contacts now are widely used in medium voltage circuit breakers. The arc motion under the transverse magnetic field (TMF) plays a decisive role in the interruption. In this paper, we focus on the movement of vacuum arc driven by TMF and anode thermal process during the arcing. Then, based on the principle of conservation, a transient two-dimensional anode activity model (subjected to TMF constricted arc) is established. The state change of material, evaporation from contacts and motion of molten pool are also considered in our model. By considering the arc motion in the anode activity model, the transient anode thermal process and the movement of constrict arc under TMF are studied, respectively. The simulation predicted that average speed of arc is not higher than 200m/s. In the simulation, the anode surface is completely melted near the current peak with 200 μm molten layer. In addition, the influence of movement of molten pool on the arc speed is analyzed, finding that the movement of the bath accelerates arc speed, but weakens the surface melting at the same time.