Inorganic fillers for corona endurance enhancement of selected polymers

In high voltage applications, polymer insulation can be exposed to very high electrical field stress, resulting in long term exposure to corona. The electrical field stress may be much below dielectric breakdown threshold. Eventually the exposure to corona can lead to failure of the high voltage component. Nanometer sized inorganic fillers are increasingly used as reinforcing materials for mechanical or thermal property improvement of polymers. Improvements in mechanical modulus or heat deflection temperature are often realized. These fillers may also increase some electrical properties such as corona endurance in polymers. Polyhedral oligomeric silsesquioxane (POSS) loaded polymers are tested for corona endurance. POSS is a synthesized silicon based cage structure with an intermediate oxidation between SiO and SiO₂. Results suggest at least a five times improvement in ac corona. lifetime of selected POSS-polymer composites.