Water content of XLPE cable insulation

The authors deal with water absorption and diffusion in various kinds of cross-linked polyethylene (XLPE) cable insulation: steam-cured, dry-cured, and with and without water tree retardant (WTR). Measurements were performed on pieces of insulation directly or on cable specimens immersed in water at different temperatures. As expected, the steam-cured insulation absorbed much more water than the dry-cured insulation, and the higher the temperature the greater was the water content. The more surprising result is that one WTR insulation absorbed even a greater amount of water than the steam-cured insulation. The results are discussed in the framework of Fick´s law and existing models of diffusion