Predicting Water Tree Growth in Polyethylene Insulation Using FE Model Based on State Variable

Paper in proceeding, 2025

Water treeing is one of the main causes of failures of dynamic high voltage cables. Predicting the development of water trees in the insulation is vital for estimations of their lifetime. In the present work, a model predicting evolution of water trees in polyethylene insulation is presented. The model is based on the solution of an electrostatic problem and utilizes a state variable, which defines respective properties of healthy and damaged regions in the material. The model is evaluated using several study cases focusing on impacts of various conditions. Thus, the development of water tree from a conical defect, long micro-crack and micro-void filled with gas are examined. The obtained tree patterns are compared with the experimentally obtained images of water trees in XLPE insulation.