Simulation of Electrode Erosion under DC Air Arc

摘要

The erosion of electrode plays a crucial role in the reliability and life of low-voltage circuit breaker. Therefore, developing a valid erosion model for a range of current is important. In this paper, the arc-electrode unified model is established to determine mass loss under direct current air arc. This model includes two types of electrode material erosion: vaporization and sputter erosion. A two-dimensional magnetic hydrodynamics (MHD) model is built. In this model, the molten pool and arc are combined together. And the energy balance on the interface between electrode and arc is considered. The erosion model is established on the basis of the molten pool model. The vaporization flux caused by concentration gradient is calculated using the Langmuir formula when the surface temperature of molten pool is lower than its boiling point. The vaporization rate caused by pressure gradient is bigger than it caused by concentration gradient. The vaporization rate caused by pressure gradient is calculated by the fundamental principles of gas dynamics. The sputter rate is obtained based on statistical methods. The influence of electrode gap on the erosion is also carried out. The simulation results are compared with the experimental results in order to verify the accuracy and validity of the simulation model in the current simulation conditions.