Calculation of Electrical Stresses in DC Cable Insulation

High-voltage dc transmission is becoming increasingly important where heavy loads are to be transmitted over long distances. While most HV dc transmission will probably be overhead, a certain amount of insulated cable will undoubtedly be used for underground, submarine, and indoor work. The electrical stresses in the insulation of such cables are important, if safe and economical designs are to be developed. Because stress distribution under direct voltage is governed primarily by resistivity, which, in turn, varies drastically with temperature, it is more difficult to calculate than the corresponding ac stress distribution. In this paper a technique of calculation is presented based on a numerical approach, which permits the dc stress distribution to be computed quite readily.