Research On Surface Flashover Characteristics Of Insulators In SF₆Gas Mixtures Between0.1MPa And0.25MPa

With the rapid devolopment of urbanization in our country, more and more C-GIS are to be apply to the factory building, the block, the subway and the high-speed railway, which increased the application amount of SF6gas. For cutting down the greenhouse effect and the environmental pollution which caused by SF6gas, it is necessary to research the alternative of SF6gas, and promote insulation of less SF6gas or none SF6gas in C-GIS industry.In this paper, a system of the surface flashover on insulator is built by redesign the present GIS equipment. The reasonable testing program is set up through the groping test. Between0.1MPa and0.25MPa gas pressure, a large number of surface flashover test on the insulator in different mixed gases(SF6, N2, Synthetic air, CO2, and the binary gas which SF6mixed with the other three gases) under different voltage waveforms(AC power frequency and negative impulse lightning) are carried out.Test results show, in the gas pressure range, the flashover voltages of insulator increase linealy as the gas pressure increases in single gas, which is independent of the voltage waveforms; In mixed gases, the flashover voltage of insulator is depended on electro negativity of SF6gas and ionization energy of the other gas. When the electro negativity of SF6gas master reaction, it happens frequently that the flashover voltage is high; In case, the ionization energy of the other gas master reaction, otherwise, the flashover voltage is low. The regular patterns of insulator surface flashover voltage varied with the SF6contents are consistent in SF6/N2mixed gases, which is independent of the voltage waveforms.Using analysis of variance method analyzes the test data, the SF6mixed gases in the gas pressure range, the change of gas pressure and SF6contents influence the flashover voltage of AC power frequency greatly, but for a little effect on flashover voliage of negative impulse lightning. SF6content is the main factor affecting the flashover voltage.According to the test results and analysis, the alternative plan of SF6in the gas pressure range is put forward.