Interaction of Biaxial Mechanical Stress with Electrical Tree Growth of Epoxy Resin

Frequent breakdown incidents occur in gas insulated transmission lines due to the exposure of epoxy insulators to a combination of complex mechanical stresses and intense electric fields. This research examines how simultaneous biaxial stresses affect the development of electrical trees by exposing epoxy resin samples to both tension and compression in perpendicular orientations. The findings reveal that tensile stress fosters electrical tree growth, whereas compressive stress initially suppresses it before facilitating growth as stress levels rise. A proposed energy model helps explain this behavior, with the tensile failure model highlighting competition and the shear failure model demonstrating cooperation. A quantitative energy model specifically for epoxy resin is introduced. The study results are aimed at providing valuable guidance for insulation design and material improvements in ultra-high voltage projects.