Space charge measurement in polymer insulated power cables using flat ground electrode PEA system

Data processing methods used to accurately determine the space charge and electric stress distributions in DC power cables using the pulsed electroacoustic (PEA) system are described. Due to the coaxial geometry and the thick-walled insulation of high-voltage cables, factors such as divergence, attenuation and dispersion of the propagated acoustic pressure wave in the PEA can strongly influence the resultant measurements. These factors are taken into account ensuring accurate measurements to be made. Most importantly, a method is presented to determine the electric stress profile across the insulation due to both the divergent applied field and that as a consequence of trapped charge in the bulk of the insulating material. Results of space-charge measurements and the corresponding derived electric stress distributions in XLPE DC cables are presented.