Modelling and simulation of anode activity in high-current vacuum arc

Abstract

Anode activity is critical for the success or failure of vacuum interrupters when the arc current attains a certain limiting value. Anode vapour from anode activity will influence high-current vacuum arc (HCVA) characteristics, and further influence interrupting successfully or not. In order to investigate the interaction between the arc column and anode vapour, a transient two-dimensional anode activity (subjected to HCVA column) model is established in this paper. Based on this model, the anode thermal process under ideal heat flux density and heat flux density from the arc column are simulated, respectively. The simulation results show that for sinusoid current, anode surface temperature first increases rapidly, then decreases slowly. With the increase in the heat flux density to the anode, the anode surface temperature will increase. The maximal value of the anode surface temperature appears near 7 ms (50 Hz current waveform), which is also in agreement with other simulation results. Anode evaporation cools the anode surface, which leads to a more uniform anode surface temperature at the contact centre than that near the contact edge. When the anode is melted, the radial distribution of the anode surface temperature appears as an inflection point. The simulation results are also compared with the experimental results and the results of other researchers. Reasonable agreement is observed. According to the anode activity model, the anode boundary condition of the HCVA model with anode vapour can be defined.