Space charge in HVDC cable insulation

High voltage cables that are used for DC transmission are subjected to a range of operating conditions. The resulting distribution of the electric field inside the cable is highly dependent on, for instance loading of the cable and polarity reversals. This is because the conductivity of the insulation is dependent both on the temperature and on the electric field. An essential parameter in the process to determine the internal electric field is space charge. For thorough understanding of the behavior of the cable, knowledge of the location and amount of space charge under different operating conditions is paramount.