Arc Motion Between the Splitter Plates of a Medium-Voltage SF6-Insulated Load Break Switch

Abstract

Arc chutes comprising ferromagnetic splitter plates are common in SF6-insulated medium-voltage switchgears. By splitting and cooling the electric arc, they help to interrupt moderate currents such as the rated current in load break switches or the transfer current in switch–fuse combinations. Between the splitter plates of such an arc chute, the motion of the arc depends on the balance of the attracting magnetic forces from the ferromagnetic plates, the repelling forces between two arc columns at the two sides of a plate, and the viscous forces from the insulating gas. We simulated this motion by calculating the magnetic forces acting on the arc columns after splitting by means of 2-D and 3-D electromagnetic finite-element analyses and by taking the viscous force as drag force into account. This paper describes this calculation method and compares the simulation results with those of laboratory tests.