Résumé
The paper presents the calculation of the electric field due to space charge associated to water trees in polyethylene-insulated power cables. For numerical computations the measured thermal step currents with currents computed with a Comsol Multiphysics software for various values of the space charge density and water trees lengths are compared. For electric field computation different average water concentrations in treed areas were considered and the influence of ionic space charge on insulation ageing is presented.