Investigation of arc contact erosion characteristics in SF₆ circuit breakers

To address the erosion of arc contacts caused by repeated current interruptions in SF₆ circuit breakers and to ensure the safe and stable operation of the power grid, this study employs numerical simulation methods to investigate the erosion characteristics of the contacts and validates the results through experiments. A thermodynamic model of arc-contact melting is established, and the level-set method is used to track the free surface while comprehensively considering heat transfer, phase change, and evaporative ablation. The temperature field, velocity field, and surface morphology evolution of the molten pool are obtained, and the melting, flow, and evaporation behavior of CuW80 contacts under a 20 kA interrupting current and a heat flux density of 4.9 × 10⁹ W/m² are systematically analyzed. The results show that the maximum temperature of the molten pool varies with the flow of the liquid metal, and the maximum depth and width of the crater are 0.09 and 1.997 mm, respectively. Under the combined action of recoil pressure, surface tension, and the Marangoni force, the maximum velocity of the liquid metal occurs in the tangential direction at the crater edge. The analysis of material properties indicates that thermal conductivity has the most significant influence on the molten-pool temperature. Reducing the latent heat of vaporization, increasing the boiling point, and decreasing the atomic molar mass can effectively suppress the evaporative mass flux, among which increasing the boiling point is the most effective. This study provides a theoretical basis for the design and optimization of arc-contact materials with enhanced erosion resistance.