Numerical Study of Influence of Frequency and Eddy Currents on Arc Motion in Low-Voltage Circuit Breaker

The air circuit breaker used for permanent magnet wind power generation systems should switch OFF the short-circuit current of variable frequencies. This paper focuses on the influence of frequency on the behavior of air arc. A 3-D magnetohydrodynamic (MHD) model of air arc plasma was developed to investigate the arc motion process at variable frequencies. In this model, the eddy currents in the whole calculation domains including the electrodes, the splitter plate, and the arc column were considered, and the magnetic vector potential approach was adopted to calculate the electromagnetic field produced by the current loop. A thin layer of elements with a nonlinear voltage-current density characteristic surrounding the splitter plate was employed to represent the formation of new arc roots and electrodes voltage drop. Based on this model, the evolutions of arc voltage, temperature, normalized time, and current density were obtained and compared among variable frequencies. The simulation results reveal that the normalized time, the eddy current density peak in splitter plate, and the arc voltage peak increase at a higher frequency.