Improvement of Surface Flashover Voltage of Vacuum Interrupter by Surface Coating

The vacuum surface flashover phenomenon limits the development of vacuum interrupter (VI) and vacuum circuit breaker (VCB) towards high voltage miniaturization. Surface flashover in VI begins at the shield ring and develops along ceramic insulator. According to the development process of vacuum surface flashover, inhibiting the initial electron emission and surface electron multiplication process are effective methods to improve surface flashover. In this paper, Al2O3 coating and Cr2O3 coating were constructed on the end of the shield ring and the surface of ceramic insulator respectively in VI bottle, and the insulation characteristics of the VI bottle under positive lightning impulse voltage were studied. The results show that the Al2O3 coating at the end of the shield ring can improve the flashover voltage by inhibiting the initial electron emission. The Cr2O3 coating on the surface of the ceramic insulator improves the flashover voltage of VI bottle by reducing the secondary electron emission coefficient of the ceramic insulator.