Dielectric Anisotropy of Resin-Impregnated Paper Materials and Its Effect on Electric Field in High-Voltage Dry-Type Bushing

The dielectric anisotropy of epoxy resin impregnated paper materials may have a significant effect on the electric field distribution and insulation properties of high voltage bushing, but current studies lack a complete characterization of this problem. In this paper, the electrical conductivity, trap property, dielectric constant and breakdown property of the epoxy impregnated paper material along different electric field directions are tested and characterized. It is found that the material resistivity and breakdown field intensity at the epoxy-paper interface which is parallel to the electric field are significantly lower than that of the interface perpendicular to the electric field, which is consistent with the test results of the trap and dielectric property of the material in different directions. At the same time, this paper has simulated the electric field distribution in the bushing considering the anisotropic properties of the material, and found that the maximum electric field increased by more than 10% compared with that without considering the anisotropy of the material, which will provide an important reference for the property regulation of the impregnated paper material and high voltage bushing design.