Numerical Study of Arc Motion Process Considering Ferromagnetic Material in Multiple Parallel Contacts System

Air circuit breaker (ACB) is widely used in power distribution system. The movable contact of ACB consist of multiple parallel contacts and the arc will be ignited when the short-circuit current appears. This paper focuses on the arc motion process in multiple parallel contacts system. A 3-D magneto-hydro-dynamic (MHD) model of multiple parallel contacts system is built. In this model, the nonlinear B-H curve of splitter plate is used in calculation. The magnetic vector potential approach is adopted to calculate the time-varying electromagnetic field produced by the current loop. The difference of voltage drop between near-anode and near-cathode is considered. In addition, the interaction among multiple parallel contacts is included in numerical simulation. Based on this calculation, the arc voltage, temperature and current density were obtained. The arc motion process is analyzed by current density and temperature. The simulation results show that the anode arc root will appears on multiple contacts with the increase of current. The upper arc moves faster than low arc after the arc column is divided by the splitter plate.