Flashover dynamic model of polluted insulators under ac voltage

This paper presents a dynamic model allowing the prediction of discharge activity leading to flashover of polluted insulators. It takes into account the instantaneous changes of the discharge (arc) parameters. For a given voltage, geometry and pollution severity, the model enables one to determine the following parameters: temporal evolution of the current, arc resistance, propagation velocity, charge injection and flashover time lag. The flashover voltage characteristic as a function of the surface conductivity of insulators calculated by this model is quite satisfactory in contrast to the empirical and semi-empirical models reported in the literature. The leakage currents computed by our model are found to be in a good agreement with those measured in the laboratory.