Research on Surface Flashover Characteristics and Improving Method along Gas-Solid Interface of Vacuum Interrupters in Environment-Friendly Tank Circuit Breakers

Environment-friendly tank vacuum circuit breakers utilizing vacuum interruption and environment-friendly gas insulation are considered an effective approach to replace SF6 circuit breakers. However, surface flashover along the gas–solid interface of the vacuum interrupter in dry air is one of the obstacles for expanding the application of tank vacuum circuit breakers. Thus, a simulation model of surface flashover along gas–solid interface of the vacuum interrupter is developed in this paper. The effects of two improving methods — installing the shielding and setting the main shield potential to 50% of the breaking voltage — on the electron density, surface charge density, and discharge velocity were investigated. Then, a surface flashover test platform was constructed, and the flashover voltages of ceramic insulators in 0.9 MPa dry air were measured both with and without methods, thereby validating the simulation model. The findings provide a theoretical basis and experimental support for enhancing the insulation of high-voltage environment-friendly vacuum circuit breakers.