Probabilistic assessment of flashover performance of transmission lines in contaminated areas

Using a probabilistic method, a risk-of-failure study of 500 kV transmission line insulation was made by treating flashover voltage, contamination severity, degree of wetting as probabilistic variables. In the present study, a calculation of risk-of-failure was made using the actually recorded distribution of contamination severity, relative humidity and flashover voltage. The results were compared with those obtained by assuming normal distribution of the two variables.