Simulation of Electric Field Distributions in Water Treed XLPE Using Finite Element Method

Water treeing is the main inducement of insulating breakdown of polyethylene power cables which are used in humid environment. Water tree may initiate electrical tree, which can eventually cause insulation breakdown of power cables. In order to study the inception and propagation mechanisms of electrical tree transformed from water tree, and to evaluate the degradation degree of water tree, it is important to acknowledge the electric field distribution in water treed XLPE. By utilizing finite element method, we simulate the water tree radius dependent internal electric field profiles in the present paper. The numerical analysis results show that maximum electric field strengths exist at the tip of water trees, demonstrate that the maximum electric field strengths first decrease and then increase with increasing the water tree radius when the applied voltage is invariant, and indicate that the partial electric field strength at the tip of water tree is weakened in the early stage.