Flashover Voltage of Outdoor Insulators in the Presence of Multiple Drybands

In this paper a model to calculate the flashover voltage of polluted outdoor insulator in the presence of multiple dryband discharges is presented. Based on the power criterion for flashover, a generalized equation is proposed that can calculated the flashover voltage for serially burning multiple discharges on the surface of the polluted insulator. The model is further used to calculate the flashover voltage of standard insulator of rating 115kV. It was found that the presence of multiple smaller dryband discharges at every shed reduced the flashover voltage of 115kV insulator with a single predominant discharge by 15%.