Effect of shed Configuration on AC Flashover Performance of Polluted Porcelain Insulators

The flashover of polluted insulator is one of the serious problems which should be taken into account in the design and coordination of high voltage insulation. In order to clarify the influence of umbrella shape configurations on the pollution flashover characteristics of AC suspension porcelain insulators, pollution flashover tests have been operated for 11 types of insulators with different umbrella shape configurations. The results indicate that the specific leakage distance increase with the enlargement of diameter and height of insulators, and the increasing severities are relevant to their umbrella shapes. The specific leakage distance of normal type insulators increase more significantly than that of outer-rib insulators with geometrical dimensions enlarging. With equal diameter or height, the specific leakage distance of normal type insulator is bigger than that of outer-rib insulator. And the leakage distance availabilities of normal insulators are superior to that of outer-rib insulator with the same geometrical dimensions. The test results also demonstrate that the contaminated flashover performances of insulators with bigger geometrical dimensions are better than that with smaller geometrical dimensions with the same umbrella shape, this is because that the bigger the geometrical dimensions, the longer the leakage length, and the contamination flashover voltage of certain pollution level is determined by both the umbrella shape configuration and the leakage length of insulator.