Effect of Mechanical Stress on Dielectric Properties of Epoxy Resin

This study examines the dielectrics properties of epoxy resin under mechanical stresses ranging from -10 to +10 MPa commonly encountered in gas insulated transmission lines (GIL) and gas insulated switchgears (GIS) systems. With the tensile stress increases, the permittivity of the epoxy resin decreases and the conductivity, trap energy level and accumulated charge increase. The opposite is true for the compressive stress case. Notably, mechanical stress has a more significant influence on conductivity than on relative permittivity. Consequently, the electric field distribution of epoxy insulators under DC is significantly more affected by externally applied mechanical stresses than under AC or overvoltage conditions. These findings emphasize the importance of considering the effect of externally applied stresses on the dielectric properties of insulators when designing them.