Numerical Simulation on Thermal Decomposition Process of Electric Arc Fault in Epoxy Resin Impregnated Paper Bushing

Once the insulation layer of the epoxy resin impregnated paper bushing breaks down, the epoxy resin would undergo thermal decomposition by the arc, causing a rapid increase in internal temperature and stress inside the bushing, which may lead to explosion and combustion. In this paper, a thermal decomposition simulation model for are faults is proposed for epoxy resin impregnated paper bushing, which calculates the temperature and stress distribution inside, so as to guide the improvement of epoxy resin impregnated paper bushing. The corresponding thermodynamic properties of epoxy resin has been characterized by TGA. Based on the typical structure of 800kV bushings, a multi-physics simulation model for thermal decomposition process in epoxy resin impregnated paper bushings has been established, coupled with heat transfer, laminar flow, and solid mechanics physical fields in consideration of the test results. During the simulation, arc fault, which is based on Mayr arc model, was set inside the bushing core and the temperature and stress distribution can be obtained. During arcing, there was a significant temperature gradient within the arc channel, which lead to great deformation inside the core of bushing. The surface of the epoxy resin impregnated paper bushing core undergoes thermal expansion due to heating, where the stress could exceed 800MPa, the bearing limit of the core, indicating great risk of explosion. The simulation method of thermal decomposition process can contribute to optimizing epoxy resin impregnated paper bushing design.