Modeling of AC flashover on ice-covered composite insulators with different shed configurations

The shed configuration has an obvious effect on flashover performance of ice-covered composite insulators. Based on the flashover arc path, a “multi-arc, multi-ice-layer” mathematical model is proposed to predict AC flashover voltages of ice-covered composite insulators with different shed configurations during the melting period. The model takes into account two different arc paths across the tip of each un-bridge icicle. Moreover, the arc across the air gap is distinguished from the arc on the ice surface, and the residual ice layer resistance is divided into icicle resistance, arc root resistance and shed surface ice resistance. In order to verify this model, four kinds of 220 kV composite insulators with different shed configurations are tested under different icing conditions. The theoretical results from the model are found to be in good agreement with the experimental results.