Analytical computation of discharge characteristic constants and critical parameters of flashover of polluted insulators

This paper presents mathematical expressions of dc and ac flashover discharge characteristic constants (n and N) of polluted insulators. It's shown that the proposed relationships of n and N are not static and they depend on the parameters of the equivalent electrical circuit and thermal characteristics of discharge. The critical voltages and currents computed using the dynamic equations of n and N we established are found in a good accordance with the experimental ones. Under dc, the temperature of the discharge channel is higher with a positive point than with a negative point. And under ac, the discharge temperature range is almost identical to that one corresponding to the dc positive polarity case.