Influence of Different Contaminants with Clean Steam fog on the Flashover behavior of Porcelain and Polymeric Insulators: An Experimental Study

Due to the rising voltage level of the power lines, the occurrence of pollution-induced flashover of the line insulators is becoming a serious issue. In this experimental study, the contamination flashover performance of three kinds of high voltage insulators energized by HVAC is evaluated. The samples were polluted artificially with five particular types of contaminants. Clean steam fog is used in order to wet the polluted samples. A comparison between the insulator flashover characteristics by measuring their surface conductivity, flashover voltages, Equivalent salt deposit density, and Non-soluble deposit density is presented. Results show that the highest flashover voltage (FOV) is found to be in dry state by the composite insulator for sand is 96 kV, and for porcelain (both fresh and serviced) insulators are 85 kV and 78 kV respectively, and least obtained for salt mixture, 88 kV for composite, 75 kV for a fresh piece of porcelain insulator and 63 kV for serviced porcelain insulator. Whereas, under wet conditions, these values of flashover voltages for the three samples are reduced by 17.7%, 22% and 30.7% for sand, and for salt mixture, values of FOV are decreased by 43.0%, 48%, and 46% respectively. Comparison analysis suggests that the composite insulators perform 5% better than porcelain insulators, even in the heavily polluted environment. This study may provide a reference to select suitable insulators for a specific area.