PROJECT TITLE :

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

ABSTRACT:

Shed configuration is one among the vital factors affecting the icing characteristics and icing flashover performance of composite insulators. During this paper, the non-energized and energized glaze icing tests are conducted on 12 types of typical 220 kV composite insulators with totally different shed configurations in the substitute climate chamber. Combining with numerical calculations of electrical field distributions, the monitoring of leakage current, the measurement of the ice-melting water conductivity and also the shooting of flashover arc methods, 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 also the lower average electric field strength across the icicle air gap, which ends up in the reduction of the icing flashover voltage. When the shed spacing is larger, each the icicle length and ice thickness become larger, and therefore the ice-melting water conductivity during the flashover is higher. However the ratio of icicle air gap arc to the flashover arc is higher and its effects on the icing flashover performance are more obvious, that leads to the development of the icing flashover voltage. When the ice accretes on the energized insulator, the ice-melting water conductivity is smaller whereas the ratio of icicle air gap arc to the flashover arc is larger than that beneath non-energized icing condition. These variations cause the upper icing flashover voltages for energized insulators. It's thus advised that the icing and flashover tests under completely different icing degrees ought to be conducted on energized composite insulators to deeply study the influences of shed configuration.