Effects of Gradient Magnetic Field on Charge Behavior and Electrical Tree Growth in Epoxy Resin

In this paper, a high-field magnet experimental system is setup to investigate the dielectric properties of epoxy resin in the presence of high magnetic field. An asymmetric ferromagnetic electrode system is used to build gradient magnetic field and investigate its effect on tree characteristics of epoxy resin. Influence mechanisms of gradient magnetic field on dielectric properties and tree characteristics of epoxy resin are discussed through combining experimental results and simulation calculation. Experimental results show that electrical trees are more easily to be initiated and spread more rapidly in gradient magnetic field. The conductivity of the epoxy resin increases with the increase of magnetic field strength due to energy level splitting, which is analyzed through electrodynamics calculation. The relative permittivity decreases, and the dielectric loss tangents increase when high magnetic field is applied. Changes of conductivity and relative permittivity affect the charge behavior and electric field distribution in epoxy resin, resulting in the particular electrical tree.