Influence of CaSO4 content in contamination on the leakage current characteristics of porcelain insulator string

Leakage current was one of the important characterize of insulators insulation and has made a lot of studies. However, there are few studies about the influence on insulator leakage current characteristics considering the percentage of CaSO₄ in contaminations. Seven pieces of suspension porcelain insulators XWP₂-160 were used as test samples, and lots of artificial pollution tests were conducted in an artificial fog chamber. The results indicated that the peak value of leakage current will decrease with the increase of the CaSO₄ percentage, in the way of negative exponential function, while the peak time of leakage current will increase in the way of positive exponential function. In addition, the value of flashover current will decrease slightly and the leakage current pulse decreases linearly with the increase of CaSO₄ percentage. The critical flashover current will reduce in the way of negative exponential power function. The results can be an important reference for external insulation design, operation and maintenance of transmission lines.