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. Measurements of two types of newly devel oped DC XLPE cables with 20-mm insulation were taken under a DC voltag e of 500 kV with the conductor temperature at room temperature and at 85 degrees 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 pol arity of the applied voltage was reversed, in the case when the conduc tor was kept at 85 degrees C. However, the distortion of the electric field was significantly less than that expected in conventional XLPE c ables. As the result, the subjected DC cables are considered to have s table DC characteristics from the viewpoint of space charge-behavior.