Selection of Coaxial Cables and Grounding Wires for 66 kV and above High-Voltage Cable Grounding

Regarding the selection of cables for grounding systems of 66 kV and above single-core high-voltage power cables, rationale behind not requiring internal and external semi-conductive shielding layers or metal shielding layers for grounding wires was analyzed, based on Design Standard for Power Engineering Cables (GB 50217—2018) and industry practice. The minimum conductor cross-section under various non-metallic sheaths was calculated according to the allowable short-circuit current on the metallic sheaths of high-voltage cables in a non-adiabatic state. Results indicated that the theoretical minimum conductor cross-section allowed by polyvinyl chloride sheath was approximately 6% larger than that allowed by polyethylene sheath. Through collaborative application of cross-connected grounding system and coaxial cables, it was possible to simultaneously achieve induced potential balancing, enhance construction reliability, and optimize operation and maintenance costs. The paper systematically discussed the selection of grounding wires, the design of cross-interconnection structures, and insulation level requirements through theoretical analysis, providing reference for engineering practice.