Effects of artificial polluting methods on AC flashover voltage of composite insulators

In artificial pollution tests, there are three polluting methods frequently used, including quantitative Brushing Method (BM), Dipping Method (DM) and Spraying Method (SM). Based on measurements of ac flashover performance of four types of silicone rubber composite insulators in the artificial climate chamber, this paper studied the differences on the flashover voltage of polluted composite insulators using these methods. The tests show that there are some differences on the pollution flashover characteristics, and the influences vary on flashover voltage of specimens using different polluting methods. Further, the differences are determined by the geometry of composite insulators as well as the polluting degree. However, the fitting formulas, which are simulated on ac pollution flashover voltages at the various pollution degrees for the same type of insulator, are consistent with three different methods. Moreover, the differences on exponents a characterizing the influence of Salt Deposit Density (SDD) on the flashover voltage are negligible for specimens whichever polluting method is used.