Wet Flashover Characteristic of Composite Post Insulators at High Altitudes

This paper presents the experimental results of five types of composite post insulators and two types of porcelain post insulators with different shed designs in natural high-altitude areas (1 970 m),on wet flashover. The solid layer method was used in experiments and 50% wet flashover voltages (U50%) were determined by using the Up-and-Down Method with negative voltage. Experimental results indicated that shed spacing had a significant influence on the contaminated water column between every two sheds,so the wet flashover voltage differed greatly with different shed design. When the shed overhang increased,the leakage distance of the post insulator enlarged. The wet flashover voltage with large shed overhang was higher than that with small shed overhang. The precipitation and the water conductivity also had great effects on the wet flashover voltage. The relationship between the wet flashover voltage and the precipitation or the water conductivity was congruous with the power function relation.