Development of contamination flashover pre-warning system and analysis of operating experience

Pollution flashover has been a serious threat to the operation safety for the power system. Online monitoring is one most important way for the operation and maintenance of power system. The leakage current on insulator surface is a comprehensive reflection of the insulator surface contamination, environmental conditions and other affecting factors. The purpose of outdoor insulation state on-line monitoring could be achieved by measuring and monitoring the leakage current on insulator surface. This paper showed that close relationship existed between leakage current in both low humidity and saturated moisture conditions. A negative exponential relationship exists between pollution flashover voltage and a new parameter I* which could reflect the insulator shape and the maximum leakage current under saturated humidity. The flashover voltage under saturated humidity could be predicted through current obtained under low humidity conditions. A contamination pre-warning system was constructed in accordance using this mathematical model combined with some hardware system. Pilot systems were established in some typical polluted area in Jiangsu Province. The results showed that the system could achieve online monitoring purposes.