Analysis of the pollution accumulation and pollution flashover performance of outdoor 500kV insulator string

It is important to study the natural characteristic of pollution accumulation and flashover performance of insulator energized the operating voltage. This paper mainly focus on the insulator strings operating in a 500kV power network in Chongqing, tests and analyzes the pollution depositing rules and flashover performance of them. Test results indicate that: the value of equivalent salt deposit density (ESDD) on the top surface of insulator is lower than that on the bottom, as well as the value of non-soluble deposit density (NSDD);the accumulation rate of NSDD is heavier than that of ESDD; electric field distribution and precipitation exert a strong influence on the insulator obviously; at the same pollution level, the flashover voltage of natural contaminated insulator is 2 times as high as that of artificial polluted insulator, which mainly caused by the difference of pollution materials and non-uniform pollution distribution on the insulator surface. The results of this paper may be the reference for external insulation coordination and design in the pollution area.