Development of 500kV DC extruded dielectric power cable

A 500kV DC extruded cable and a factory joint have been developed. As the first step of this development, space charge accumulation in insulation material is studied. DC high electric field accumulates space charges, and causes local increase of the electric field, which can lead to breakdown. I order to resolve this problem, polyethylene with polarity organic matter is selected as dielectric material for the DC power cable. Model cables, which ave 9mm dielectric layer thickness, were made and these DC performances were evaluated. As the result, it is confirmed that hese cables have much higher DC breakdown strength and smaller accumulation f space charge than XLPE cables. For the next step, a full-size 500kV DC extruded dielectric submarine cable with a factory joint was designed, and manufactured. The thickness of the insulation is designed as 23mm with consideration f space charge influences. Voltage withstand tests were carried out after mechanical tests which simulate he equivalent damage during cable laying into the sea. As the result, it was confirmed that the developed DC cable has sufficient initial electrical properties a an UHV DC power cable.