Space charge behavior in full-size 250 kV DC XLPE cables

The space charge in full size 250 kV DC cables was measured using the pulse-electroacoustic method. Measurementsof two types of newly developed DC XLPE cables with 20-mm insulation were taken under a DC voltage of 500 kV with the conductor temperature at: room tempera~ure and at 85 “c. A qualitative analysis of the space-charge distribution and a quantitative analysis of the electric fields in the vicinity of semicon interfaces were conducted. It was shown that the field in the vicinity of the inner semicon tends to increase by 10-40% when the polarity of the applied voltage was reversed, in the case when the conductor was kept at 85 -C. However, the distortion of the electric field was significantly less than that expected in conventional XLPE cables. As the result, the subjected DC cables are considered to have stable DC characteristics from the viewpoint of space chargebehavior.