Influence of shed configuration on icing characteristics and flashover performance of 220 kV composite insulators

Abstract

Shed configuration is one of the important factors affecting the icing characteristics and icing flashover performance of composite insulators. In this paper, the non-energized and energized glaze icing tests are conducted on 12 types of typical 220 kV composite insulators with different shed configurations in the artificial climate chamber. Combining with numerical calculations of electrical field distributions, the monitoring of leakage current, the measurement of the ice-melting water conductivity and the shooting of flashover arc paths, the influences of shed configuration on the ice growth and icing flashover voltages of composite insulators are comprehensively analyzed. Results indicate that a larger shed diameter brings about the faster ice growth and the lower average electric field strength across the icicle air gap, which leads to the reduction of the icing flashover voltage. When the shed spacing is larger, both the icicle length and ice thickness become larger, and the ice-melting water conductivity during the flashover is higher. But the ratio of icicle air gap arc to the flashover arc is higher and its effects on the icing flashover performance are more obvious, which leads to the improvement of the icing flashover voltage. When the ice accretes on the energized insulator, the ice-melting water conductivity is smaller while the ratio of icicle air gap arc to the flashover arc is larger than that under non-energized icing condition. These variations lead to the higher icing flashover voltages for energized insulators. It is thus suggested that the icing and flashover tests under different icing degrees should be conducted on energized composite insulators to deeply study the influences of shed configuration.