Estimation of Electric Field Distribution in a 220KV HVAC XLPE Cable Under Differential Ageing

Inhomogeneous temperature distribution within the bulk of the cable insulation can lead to unexpected conductivity variations at different radial positions of the insulation. Consequently, when estimating the electric field, considering the cable insulation as a homogeneous bulk may not provide an accurate model. In this paper cable insulation is peeled out from 220kV XLPE cable at equidistant radial position from conductor. Volumetric current at 50kv/mm at 40 °C for 1 hour is measured for all layers and conductivity equation is estimated. This conductivity equation is used for estimation of electric field inside the bulk of cable insulation using FEM based COMSOL Multiphysics software. Estimation of electric field based on spatial conductivity has been done and compared with electric field estimated considering conductivity as bulk property of cable insulation.