Simulation Study of the Influence of Wall Ablation on Arc Behavior in a Low-Voltage Circuit Breaker

This paper focuses on the numerical research of the influence of polymer (polyoxymethylene) on the arc behavior during arc-motion process. The mathematical model of 3-D air-arc plasma considering the ablation of sidewalls is built based on magnetic hydrodynamics. The mass-fraction equation is introduced to the model on the basis of traditional mass, momentum, and energy-balance equations. The influence of wall ablation on the thermodynamic and transport properties of air-polymer mixtures is considered in this paper. The distributions of temperature field, pressure field, and mass fraction in the arc chamber are calculated. The simulation results indicate that the vapor concentration behind the arc column is higher than that in front of the arc column because of the existence of ldquovortexrdquo in the arc chamber. The use of polymers could accelerate arc movement and reduce the probability of occurrence of back-striking. Using polymers can also increase arc voltage, which can be explained by the change of electrical conductivity for air-polymer vapor mixtures.