Research on the Improvement of Vacuum Surface Insulation Properties of Vacuum Interrupter by Constructing Alumina Coating on the End Surface of Shield Ring
Feng Minglu, Li Haomin, Liu Zhiyuan, Geng Yingsan, Wang Jianhua
School of Electrical Engineering Xi’an Jiaotong University Xi’an 710049 China
Abstract：The vacuum surface flashover at high voltage limits the development of vacuum interrupters (VIs) towards high voltage and miniaturization. To improve the vacuum flashover voltage of VIs, this paper proposes a method to suppress electron emission by applying an alumina coating at the end of the shield ring. Atmospheric plasma spraying was used to deposit tens of micrometers of alumina on the end of the shield ring and to investigate the effect of the alumina coating on the surface insulation characteristics of VI. The surface insulation characteristics of the VI samples were tested under a positive lightning-impulse voltage, and the voltage and cathode-current waveforms during flashover were recorded. The electric field distribution before and after the alumina coating was compared using finite element simulations. The surface work function of the shield before and after alumina coating was compared by ultraviolet photoelectron spectroscopy. After the insulation experiment on the VI samples, the surface morphology and elemental distribution of the shield ring were analyzed using a scanning electron microscope and an energy-dispersive spectrometer. The results show that the alumina coating can significantly improve the electric field distribution on the shield ring surface and reduce the maximum electric field intensity by 89.4%. The surface work function of the shield ring increases from 4.51 eV to 5.39 eV, a 19.5% increase. Under the positive lightning impulse voltage, when the coating thickness at the end of the shield ring is 40 micrometers, the maximum withstand voltage of the vacuum interrupter is 12.8% higher than that without coating, and the flashover voltage U50 is increased by 17.3%. The alumina coating on the shield ring surface inhibits the current pulse generated by the explosive electron emission. It acts as a physical barrier to block the explosive electron emission into the vacuum. This study provides a theoretical basis for improving the surface insulation and miniaturizing vacuum interrupters.
冯明路, 李昊旻, 刘志远, 耿英三, 王建华. 屏蔽罩端部表面氧化铝涂层对真空灭弧室沿面绝缘特性提升研究[J]. 电工技术学报, 2026, 41(8): 2867-2878.
Feng Minglu, Li Haomin, Liu Zhiyuan, Geng Yingsan, Wang Jianhua. Research on the Improvement of Vacuum Surface Insulation Properties of Vacuum Interrupter by Constructing Alumina Coating on the End Surface of Shield Ring. Transactions of China Electrotechnical Society, 2026, 41(8): 2867-2878.
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