The influence of dielectric permittivity and its distribution on water tree initiation and growth in XLPE cables

During the growth of water trees in the XLPE cable insulation, the distribution of the electric field is modified because of the local change of the dielectric properties of the material. A better knowledge of the comparative danger for the different kinds of water trees could lead to a way of improving the quality of cable insulation. Numerical analysis results show that the dielectric permittivity of a water tree itself and its distribution inside it are so influential to the electric field intensity both in the tip and on the surface of the water tree that they may play important roles both in water tree inception and growth and in the morphology of water treeing.