Partially conducting insulation materials for high voltage overhead applications

Insulation flashover under polluted environment has emerged as a serious problem in the past two decades. The deposition of air borne natural and man made pollutants on the insulation surface has become the second major cause of line outages in the United States of America. When dry, these contaminants form a non-uniform layer of high resistance on the insulator surface. In the presence of moisture (rain, fog, etc.) the layer´s resistance is reduced resulting in surface leakage current. This causes the surface to dry unevenly leading to the formation of ?dry bands? which support a greater portion of the voltage than the wet parts, which may lead to a flashover under suitable circumstances. In the search for solution to the problem we have reviewed and investigated new materials. Our studies were concentrated on the development of partially conducting synthetic materials for use as overhead anti-pollution insulators.