Space charge measurements in high voltage DC extruded cables in IEEE Standard 1732

Recently, the number of installed high voltage DC (HVDC) links using cables with extruded insulation has dramatically increased, since extruded insulation has several advantages over traditional oil-paper insulation for cables: easier splicing, no oil use, and higher service temperature [1], [2]. Conversely, a disadvantage of HVDC extruded cables is space charge (SC) buildup with HVDC. This is a critical issue because it further complicates the nontrivial DC electric field distribution within the insulation, which is also affected by temperature [1]. It is for this reason that considerable R&D of HVDC extruded cables has been devoted to the measurement of SC, and this has contributed to attaining the present day voltage and power ratings of 320 to 400 kV and 1,000 MW per bipole, respectively [3].