Optimization Design of Coaxial Cable with Medium Voltage Cross-Linked Polyethylene Insulation and Concentric Conductor Structure

To address blind spots in current concentric conductor design of medium voltage cross-linked polyethylene insulated coaxial cables, caused by lack of standardized methods and strong coupling between structural parameters and outer diameter of the conductor, a quantitative structural optimization design system was proposed in the paper. The method determined concentric conductor resistivity based on lay factor (λ) and single wire resistivity, calculated theoretical cross-sectional area using DC resistance specified in Conductors of Insulated Cables (GB/T 3956—2008), and derived analytical solutions for single wire diameter (d) and the number of wires (n) based on geometric relationship between the number of layers, outer diameter of cable core, and theoretical cross-sectional area. Taking a 240 mm² cable as the research object, the system yielded an optimized solution: n=33, d=2.98 mm, λ=1.028. Measured verification showed: actual conductor cross-sectional area was 236.1 mm², DC resistance was 0.0750 Ω·km⁻¹, and resistivity was 17.698 Ω·mm²·km⁻¹. All indicators could exceed standard requirements, with resistivity fluctuation limited to only 0.15%. The "electrical-geometric" integrated design model developed in the paper clarified quantitative correlation of key parameters, effectively resolving blindness of traditional empirical design, which could provide a reliable theoretical basis and technical tool for standardized design and process control of coaxial cable concentric conductors, demonstrating significant engineering application value.