Effects of icing degree on ice growth characteristics and flashover performance of 220 kV composite insulators

Abstract

Icing degree is one of the important factors influencing insulator's icing flashover performance. But there may be differences between the effects of icing degree under non-energized and energized icing conditions. For this purpose, the comparative tests of non-energized and energized glaze ice accumulation are conducted on 2 types of typical 220kV composite insulators under different icing degrees in this paper. Combining with the numerical calculation of electric field distribution, the monitoring of leakage current, the measurement of the ice-melting water conductivity and the observation of flashover arc paths, the influences of icing degree on ice growth characteristics and flashover voltages of composite insulators are deeply analyzed. Results indicate that with the increase of icing degree, all relevant ice parameters gradually increase but their regularities are related to the shed configuration and the position of sheds as well as whether the ice deposits on non-energized or energized insulators. These variations lead to differences of the quantity and length of icicle air gaps and the conductivity of the water film on the ice surface, and then affect the flashover arc path and icing flashover voltage. The icing flashover voltages of energized ice-covered insulators are higher than that under non-energized condition and their difference becomes larger with the increase of icing degree while the effect of shed configuration on the icing flashover performance gradually becomes less apparent when the icing becomes heavier.