Flashover voltage of contaminated insulators

Methods have been developed for the calculation of flashover voltage of contaminated circular strip models and outdoor insulators of practical but simple geometric shape. The criteria for discharge elongation and the assumptions made are examined. A typical flow diagram of the programs for evaluating the critical values using the equations derived is given. Variations of critical current and voltage for discharge elongation with the position of the discharge root are shown. Calculated values are compared with a few published test results. For the practical insulator of simple geometry, the initial discharges are assumed to occur across the narrow core regions. Effects of variation of certain parameters on the flashover voltage are considered. It is believed that the methods developed would be useful and complementary to other experimental methods and aid insulator design