Numerical simulation of local electric field distribution in epoxy/alumina nanocomposites at LN2 temperature

Abstract

Abstract Epoxy-based nanocomposites with excellent insulation characteristics are attracting extensive attention as a new insulating material for superconducting transmission. However, it is difficult to design the composite insulation layer of cables owing to limited knowledge of the local electric field distribution in nanocomposites at cryogenic temperatures. In this work, a numerical investigation of local electric field distribution in epoxy/alumina nanocomposites at room (298 K) and liquid nitrogen (LN2) temperature (77 K) was conducted under the COMSOL Multiphysics environment. Typical needle-plate electrode configuration and thermal and static electric field coupling are constructed. Based on the simulation results, it is shown that electric field distortion may occur near the needle tip due to the difference in dielectric permittivity between alumina and epoxy matrix; however, the distortion brought on by the nanoparticle and its hindering effect limit each other. The maximum electric field does not always increase with the enhancement of filler contents. Cryogenic environments can change the electric field distribution in nanocomposites but not independently in pure epoxy. In the nanocomposites, cryogenic environments do not effectively limit partial discharge by changing the electric field distribution. Its greater contribution is to limit the movement of molecular chains and work with the nanoparticles to transfer the heat generated by partial discharge.