THERMAL-ELECTRIC FIELD DISTRIBUTION AROUND A DEFECT IN POLYETHYLENE

In the presence of a stress enhancement, a lightning surge causes spac e charge formation and power dissipation which can result in substanti al temperature rise in the dielectric. Poisson's equation and the ther mal diffusion equation have been solved in 2D with field-dependent mat erial parameters to compute temperature rises of over 80 K during a 10 0 ns risetime surge which produces a background field of 40 kV/mm appl ied to a 100 mu m protrusion with a 0.5 mu m tip radius. Such a temper ature rise could play a major role in the lightning-induced conversion of water trees to electrical trees.