Slow processes in a solid dielectric and an optimal temperature for polymerization

摘要

Long-term observations of specimens of mica-paper-epoxy insulation with different temperatures of polymerization revealed a series of slow processes in a dielectric: 1) over polymerization going even at an indoor temperature; 2) hygroscopic moistening caused by formation of micropores; 3) grow of the partial discharge level conditioned by occurrence of macropores. The last two processes are connected with internal thermal-mechanical stresses in the solid composite, whose components have different temperature coefficients of linear expansion. The optimal conditions for the polymerization are defined, at which no microcracks occur in the composite dielectric.