Design of DC Cable Accessories for Suppressing Interface Space Charge

Space charge accumulation at the interface of cable accessory insulation causes distortion of partial electric field, and it has become one of the main factors restraining the development of DC cable accessory. To this end, we presented a novel concept for DC cable accessory design, i.e. molding crosslink polyethylene material, which has similar properties to cable insulation, on cable insulation layer to form stress-relief cone and enhanced accessory insulation. Cable insulation and the enhanced insulation of accessory fuse well at the interface between them; this eliminates the interface to an extent and hence suppresses the accumulation of space charge fundamentally. Following this concept, interface-free accessories for ±200 k V DC power cables were developed and passed the type test recommended by CIGRE TB 496, which verified the proposed design concept.