Study on the flashover performance of various types of insulators polluted by nitrates

Pollution materials affect insulator flashover performance, and there is long-term significance in researching it. In this paper, common kinds of nitrates were used as the soluble pollution, and the ac flashover performance of four types of insulators under different nitrates were investigated. Basing on a large amount of primary data, the calculation of flashover gradient in specific to different pollution materials was discussed, and the effects of nitrates on it were analyzed. Research results indicate that, flashover gradient of insulator under nitrates is commonly higher than that under NaCl; among the nitrates, KNO3 corresponds to lower insulator flashover gradient while Ca(NO3)2 corresponds to a higher one; the exponent b, which characterizing the influence of ESDD on flashover gradient, is lower under nitrites than that under NaCl; for the four insulator samples polluted by nitrates, the flashover gradient of the porcelain type can be expressed by A×ESDD-0.21×NSDD-0.16, the flashover gradient EL of the glass type can be expressed by A×ESDD-0.22×NSDD-0.14, while that of the composite samples can be expressed by A×ESDD-0.19×NSDD-0.13. Research data may provide references for the better prediction of flashover voltage as well as for the better design of external insulation.