Observation of surface flashover process on high voltage polluted insulators near shoreline

This paper attempts to provide a relevant information on the serious threats of contamination surface flashover and related discharges on insulators near coastal areas. The reliability of power network systems can be improved by reducing the hazard of contamination surface flashover. A test method was adopted to examine the surface flashover process. To replicate typical coastal area contamination, a modified solid layer contamination deposition method was used in the experimental work. Two configurations were studied: 1) by turning the artificial contamination setup and cold fog generation continuously “ON” and, 2) with “ON/OFF” cycles of contamination and cold fog. The contamination and cold fog were used under different conductivities. The insulator was hung vertically in an environmental chamber simulating natural climate conditions. The results showed that flashover voltage decreased as cold fog-water conductivity and contamination level were increased. It was found that the extreme period as when surface flashover was at its lowest, after twenty minutes of cold fog generation, at a cold fog conductivity of 250 μS/cm. Visual observation results indicated that partial discharge propagated increasingly with leakage current before the occurrence of surface flashover, and that the latter occurred during “OFF” conditions when cold fog generation was suspended for a moment.