A study on the shed design of DC composite insulator under contamination flashover

The DC contamination flashover performance of composite insulators with different sheds design has been investigated at high altitude using up and down method. The experimental results demonstrated that the 50% flashover voltage do not have a monotonic relation with the leakage distance, which is different from classical theory. The shed spacing and the shed dimensions both have significant influence on the flashover performance. An arc propagation model based on probability is described to show the effect of shed design on the flashover voltage. The agreement between this model and the experimental results can be well satisfied.