Distribution of the electric field in the discharge interval under AC voltage on contaminated electrolytic surfaces simulated HV polluted insulator

Most previous works treat improving the flashover resistance of electrical equipment energized in polluted environments under a global aspect and search for the critical conditions in which the discharge will be burned during its elongation on models often brought back to only one dimension. The values of electric field calculated to the leader of the discharge are very lower to the dielectric rigidity of the surrounding air and don´t permit to explain the lengthening of the discharge. In this work, we develop a survey of the distribution of the electric field in the inter-electrode space and to the neighborhood of the leader of the discharge while taking into account the real geometry of the laboratory model. These electric parameters have been compared experimentally to those recorded on this experimental device. Our results justify the presence forward of the main discharge of a zone of photo-ionization in which can develop the streamers serving precursors to its extension.