A new model for water treeing phenomena in insulating polymers

Laboratory experiments were conducted to study the structure of water trees grown in low density polyethylene (LDPE) specimens under accelerated test conditions. A new model was developed to simulate the WT Phenomena using a novel computer technique applying the finite difference method (FDM) to calculate the equipotential distribution in the point-plane electrode system which simulates the vented water trees growth model. The distribution of the electric field was derived from the electrical potential. Those results were compared with the results developed using Finite Elements Methods (FEM) and Field Mapping Method (FMM) and the three methods gave very similar results. In this model the influence of the different factors and parameters are presented separately, so that each factor can be studied thoroughly. The FDM was further adopted to develop FORTRAN programs which simulate the initiation and growth of WTs in different materials with different water tree permittivities. The Water Trees Propagation was programmed and simulated. This simulated computer work was compared with the experimental findings and it showed to be consistent. The mechanism of water treeing is discussed according to the experimental and simulated results. The effect of ageing parameters on WT growth and the possible mechanisms of growth are considered