Overall design of supertension cables

The author describes how, during the design of supertension (66 kV to 500 kV) polymeric power cables, it is necessary to not only consider the electrical performance of the dielectric but also the correct choice of overall cable design to perform a variety of functions. The polymeric insulation must be protected from the surrounding environment by a radial metallic moisture barrier and suitable protection from the forces generated by thermal expansion, installation conditions or accidental damage. In service the core protection will be subjected to: (1) capacitive charging currents; (2) circulating currents; (3) transient fault currents; and (4) transient voltages which all must be designed for and adequately dissipated. The cable design is completed with a polymeric oversheath which can be modified to be abrasion resistant, termite resistant or have enhanced fire performance to suit the particular installation conditions. All of these influences must be considered in the overall design of a supertension polymeric cable