Breakdown characteristics of rod-plane gap under salt fog for AC and DC voltages

AC and DC breakdown test results are presented for rod-plane gaps under salt fog. It is found that, in general, there may be no significant change in the breakdown values of the gaps even under severe saline pollution in case of both AC and DC voltages. The breakdown voltage values are, however, very much lower in the case of DC negative voltages under salt fog conditions than under dry conditions. This may be one of the reasons for the arc bridging of the underribs of a polluted insulator under DC negative voltages