Influence of Electrode Erosion Caused by Interphase Short- Circuit Arcing on Thermal-Pressure Effects in the Switchgear

The phase-to-phase short circuit arcing faults occurs frequently inside switchgear. The high-temperature arc can ablate the busbars, generating metal vapor which affects the thermal-pressure effects inside the enclosure. However, the effect of interphase busbar erosion on thermal-pressure effects is not clear. In this paper, a coupled model of air arc and busbar erosion is established based on magnetohydrodynamics (MHD) theory and considering the convection and diffusion effects of metal vapor. Taking the cable compartment of the high-voltage switchgear as research object, the phase-to-phase short circuit arcing between the busbars was simulated, and the variations of temperature, pressure rise, and metal vapor within the compartment were analyzed. Furthermore, the impact of arcing positions on thermal-pressure effects was studied. The results indicate that the more serious erosion of the busbar, the greater reduction in the maximum temperature and pressure rise within the compartment. The erosion mass of the busbars is about 1.53 g under the condition of short-circuit current 40 kA and arcing time 20 ms. Changes in the arc position result in variations in the thermal-pressure effects within the compartment.