Analysis of Water Trees and Characterization Techniques in Xlpe Cables

The full form of XLPE is cross linked polyethylene. It has become the universally preferred insulation for power cables, both for distribution and transmission system applications. This type of insulation system provides cost efficiency in operations as well as lower environmental and maintenance requirements when compared to older conventional methods.In this paper, to understand the insulation recovery phenomenon of water-tree cables when an applied voltage is removed, the insulation recovery mechanism of the water tree cable is analyzed. Depending on the geometric size by micro observations of water-tree slices, a water tree model is constructed for electric field simulation, which includes a series of water-filled micro voids and interconnected channels. According to analysis of the electric field force and the mechanical properties of water tree region, the force generated by the elastic deformation of the molecular chains results in the shrinking of the channels. The breakdown strength of impulse voltage of all cables decreased during aging; the cable with the least ac voltage breakdown also has the lowest impulse voltage breakdown. Today XLPE is rapidly becoming the preferred insulation system for even the highest transmission voltages. This preference is due to the high reliability, low dielectric losses, and low environmental impact that can be achieved with XLPE. In recent developments in cable production, materials and material handling techniques have together resulted in greater improvement in electrical performance. Keywords: Adiabatic Short Circuit Current, Ageing, Cable Insulation, Insulation, Quality, Testing, Water Trees, XLPE Cable