Some Considerations on AC Water Trees in Crosslinked Polyethylene

This paper first confirms that moisture absorption of XLPE (crosslinked polyethylene) obeys Fick's law. The effects of moisture absorption and temperature on water treeing in XLPE are then discussed. The results of physical and chemical tests of the sites of water trees are presented. Infrared Fourier Transform Spectro-scopy (FT-IR) test results show the chemical aspects of the deterioration. Finally, the authors suggest that the water tree is due to a shift in chemical equilibrium (free energy) of the insulating materials due to the impressed electric field.