Study on the Behavior of Polluted Insulators Under Lightning Impulse Stress

This paper presents a method to determine leakage current and thermal losses on the polluted insulators under lightning stress based on equivalent electrical model using ATP software. Thickness of pollution layer and the ratio of pollution-covered length and also steepness of the impulse voltage can cause variations of the leakage current and thermal losses. The results demonstrate that leakage currents were dramatically increased under different pollution conditions. The consequential mathematical equations show that the rate of leakage current can be controlled by limiting of the length and thickness of pollution layer. Also the humidity evaporated from insulator´s surface due to thermal losses can be determined.