Analysis on natural contamination depositing characteristics of imitative insulator string for overhead transmission line in Shantou

Under drizzle, light rain, heavy fog and other adverse weather conditions, polluted insulators may flashover under an operating voltage which serious threat to reliable operation of power systems. Therefore, it is very important to understand the natural pollution accumulating rule of insulator energized in the operating voltage. This paper takes the XP-70 insulator string being suspended without voltage in a certain power network in Shantou as the sample, tests and analyzes the pollution depositing rules of it. Test results indicate that: The performance of natural pollution deposit is related to geographic location and voltage class. The accumulation rate of non-soluble salt deposit density (NSDD) on the surface of insulator is more serious than that of equivalent salt deposit density (ESDD). The pollution depositing situation of insulator is different under different voltage classes, the pollution accumulating situation of the 110kV line is the most severe, while that of the 220kV line is a bit lighter and the 500 kV line is the lightest. The pollution levels of transmission lines in Shantou area are mainly c and d. The test results can be used to draw the map of pollution areas, help workers to clean insulators and direct external insulation coordination and design in the pollution area.