Electric field distribution in power cable insulation affected by water trees

Electrostatic numerical models of cable insulation affected by cavities, vented and bow-tie water trees are proposed in this study. The influence of the vented tree lengths on the electric field in the untreed polymer, in a cavity in front of the tree, and in a bow-tie tree growing toward the vented tree is analyzed. The values and spatial distribution of relative permittivity and space charge in the subdomains of the 3D computational domain are set by scaling experimental results from literature. The models are implemented in the finite element method based on the software package COMSOL Multiphysics.