Space Charge Accumulation under the Effects of Temperature Gradient on Solid Dielectric Dc Cable

It is well known that existence and accumulation of space charge within the insulating material poses threat to the reliability in the operation of dc power cables. When the cables are loaded under high voltage direct current (HVDC), temperature gradient is developed across the insulation material. In this paper, commercial ac XLPE power cables were used under an application voltage of 80 kV dc with different temperature gradients loaded between the insulating material. Space charge distributions were then measured across the insulation of the cable by means of a modified pulsed electroacoustic (PEA) system with a current transformer attached. Therefore, a replica of a power cable under load conditions could be obtained, which allows us to investigate the formation, migration and accumulation of space charges in a power cable both without and with different temperature gradients consideration across the bulk of the insulating material. Discussion will be made thoroughly in order to understand the space charge phenomenon of power cable under its service temperature.