Surface tracking on porcelain insulating material and determination of DC pollution performance of insulators

A modified inclined-plane tracking test, the results of which allow prediction of DC pollution flashover voltage of insulators to a great accuracy, is proposed. Results obtained using this test are presented. The DC specific leakage distance has to be higher than the AC value by at least 30% from the point of withstanding light pollution severity. Porcelain deteriorates and fails due to erosion and tracking under combined effects of DC stress and atmospheric pollution. Positive DC stressing yields the worst case of pollution severity. The poor performance of polluted insulators is attributed to erosion and tracking phenomena. Wherever the DC test source is inadequate for artificial pollution testing on high-voltage insulators, results from surface tracking tests as prescribed using a stiff low-voltage source can be used to estimate the pollution performance of insulators under DC stressing