Electrical Insulation: XLPE Versus Conventional Materials

The first part of this chapter presents information about the evolution of power cables and their insulation materials as papers, oils, natural and synthetic rubbers, polyethylene, polyvinyl chloride, polypropylene, polytetrafluoroethylene, etc. The second part analyzes comparatively the values of typical properties of these materials, which are important for the operation of insulation, and their changes under the electrical, thermal, mechanical, and environmental stresses. The variations of conductivity and electrical permittivity, loss factors, and dielectric strength under the action of electric field and temperature are described, as well as the accumulation of space charge and tracking, partial discharges, electrical, and water treeing resistance of DC and AC cable insulation. Among the thermal properties, thermal expansion, thermal conductivity, thermal stability, melting effect, and working temperature are analyzed, and among the mechanical ones are the elasticity, elongation at traction, tensile strength, strength, compressibility, and hardness. The chapter continues with the presentation of chemical, microorganisms, termites, rodents, and resistance to radiation and the estimated lifetime of cable insulation. Finally, the conclusions are shown that XLPE has higher values for most of the properties and are recommended in the manufacture of DC and AC power cables.