AC flashover performance and voltage of long polluted and iced XP-70 suspension insulator string

Based on a series of systematic laboratory investigation carried out on the flashover of strings of three to twenty-one suspension insulator units ice-covered with polluted spraying water aimed at obtaining the AC flashover performance and voltage, this paper discusses the flashover performance and voltage of long iced XP-70 insulator string. According to the analysis of tested results, it puts forward that the product /spl sigma//sub 0/ of the icing water conductivity /spl gamma//sub 20/ converted to the value of 20/spl deg/C and the average ice amount w accreted on each insulator unit could be used as a characteristic parameter to show the effect of the ice and the contaminated icing water as well as the pre-contamination of the insulator on the minimum flashover voltage, and that the minimum flashover voltage of an iced insulator string in the severe ice-covered state can be expressed as a power function of /spl sigma//sub 0/ by a index of -0.32. And it indicates that the minimum flashover voltage of an ice-covered XP-70 insulator string is direct proportional to the units or length of an insulator string.