To analyse the lightning impulse breakdown characteristics of the parallel gaps of contaminated insulators with different salt densities,the SC-210 porcelain cross-arm insulator was used to conduct the lightning impulse test. Comparing with the electric field simulation results of the clean and contaminated insulators,the phenomenon of flashover along the surface of the insulator was analysed several times during the test. The tests and analysis indicate that in case of the SC-210 porcelain cross-arm instal...