Changes of dielectric properties evoked by extreme stress conditions

The insulating systems used for construction of electric equipments-which are subjected to extreme conditions, such as temperature about 300°C, during full electric and mechanical stress-must have unique properties. The construction of such insulating systems requires new and original materials. The main aim of our investigation is to show, how do the chosen material (based on mica and silicone bond) properties change after extreme stress, which means thermal shock of 320°C during 500 hours followed by electric stress of 10-17 kV/mm. As obtained measurement results of phenomenological as well as structural parameters indicate, there exists certain limit, which predicates about overcoming of irreversibility limit of properties and also about irreversible changes in inner structure of materials leading to marked material degradation.