Influence of insulator string positioning on AC icing flashover performance

This paper presents the relationship between ac flashover voltage and the varying positioning of iced insulator strings under different icing condition. The results were obtained through laboratory test in multifunction artificial climate chamber located at Chongqing University, China. Also difference of the ac icing flashover performance of single insulator string, double insulator strings, inverted v-type insulator strings and insulators connected with alternately large and small diameter sheds (CALSDS) were analyzed in this paper. According to test results, it is found that the distorted electric field distribution on iced insulator string is the main reason that results in the decrease of flashover voltage. With the same icing degree, the icing flashover voltage of either double insulator strings or as an inverted v-type is lower than that of single insulator string. If insulators are arranged with the type of CALSDS, the speed of icicles to bridge the insulators will decrease. To ensure the height of conductor from the earth remaining unchanged, the ac icing flashover voltage of insulator string can be increased by arranging the insulator strings as an inverted v-type or arranging the insulators with the types of CALSDS with the pattern of "3+1" or "4+1".