Flashover performance and voltage correction of iced and polluted HV insulator string at high altitude of 4000 m and above

Based on the test results carried out on several types porcelain and AC composite insulators as well as a DC insulator in the artificial climate chamber, this paper puts forward the flashover performance of tested insulators at the atmospheric pressure of the altitude of 4000-meter and above concomitant with the contamination and the icing, and analyzes the effect of the pressures and the contaminations as well as the ice amount accreted on the AC and the DC flashover voltages of the insulators respectively. And the flashover voltage correction factors of the tested insulators in the coexisting conditions of the high altitude and the contamination as well as the icing and the corresponding characteristic index are given. According to test results, it indicates that the flashover voltage of tested insulators decrease by the exponential function law with the increase of the ice amount, by the power function with the decrease of the altitude and the contamination, and the special exponents, which show the effects of the altitude, the contamination and the ice respectively, are various with the type of the insulators, the kind of voltages, and the contamination level and the ice amount.