Study of Arc Motion and Switching Performance in DC Magnetic Contactors

Direct current (DC) switching is more challenging than alternating current (AC) one since there is no natural current zero point in a DC system. Unlike AC magnetic contactors (MCs), the quenching chamber of DC MCs is composed of permanent magnets and non-ferromagnetic splitter plates. In this paper, DC switching principle is reviewed by showing the current-voltage relationship in a DC circuit. In addition, a simulation and experimental investigation has been carried out regarding arc motion and switching performance of DC MCs. It is found that the combination of non-ferromagnetic plates and permanent magnets allows the generation of sufficient Lorentz force to make the arc enter the splitter plates, leading to the DC arc interruption at the current zero point.