Electrical property of different types insulator string under typical pollution constituents

The external insulation contamination on real transmission line is mainly composed by the mixture of NaCl, CaSO₄ and other various kinds of constituents. Different constituents have effects on the flashover performance of various types insulator, but it is still not considered by the existing standard about external insulation design in polluted region. This paper investigated the electrical property of different types of insulator string under typical pollution constituents. During the tests, the insulator samples were polluted by NaCl, CaSO₄ and mixture pollution constituents in representative region respectively. The flashover data was obtained and then the waste rate of insulation were calculated based on pollution withstand voltage method. Research results indicate that, The characteristic b of ceramic, glass and composite insulator under mixture constituents pollution is obviously lower than that under NaCl, traditional design method overrates the influence of ESDD on flashover performance; the electrical property of applied insulator under mixture pollution constituents should be studied to provide better reference for the external insulation design; When using the pollution withstand method to design the external insulation, the leakage distance of insulation should be chosen basing on the mixture pollution constituents in practical region.