Design, Manufacturing, and Process Control of Large-Section Shaped Wire Copper Conductor Stranding Structure

To address the issues of low filling coefficients in traditional round wire stranding, high equipment requirements for full trapezoidal wire stranding, and excessive trapezoidal wire specifications in the manufacturing of large-section copper conductors, this paper proposes a hybrid round-trapezoidal wire stranded conductor structure. Through geometric modeling, a structural model was established with seven round copper wires as the central layer and uniform trapezoidal copper wire specifications for the adjacent inner and outer layers. Simulation results indicate that this structure achieves a compaction coefficient of 0.97~0.98. Taking 300 mm² and 400 mm² copper conductors as examples, key process parameters such as trapezoidal wire specification selection, compaction mold ratio, pitch-to-diameter ratio optimization (adjacent inner layer 23~30, outer layer 14~16), and wire drawing annealing (elongation 34%~37%) were detailed. Measured data show that the average DC resistance margins for the 300 mm² and 400 mm² hybrid structure conductors are 0.40% and 0.37%, respectively, with unit length mass reductions of 1.87% and 3.06% compared to traditional round wire conductors, matching the performance of fully trapezoidal copper conductors. The production of hybrid stranded copper conductors in 2024 resulted in a cumulative saving of 63.13 tons of copper. Compared to the full trapezoidal wire solution, trapezoidal wire specifications were reduced by 60%, enabling production with a 54-drum three-segment frame stranding machine and a 20% reduction in stranding mold change time. This hybrid stranding structure achieves high filling, low cost, and high efficiency engineering goals while ensuring DC resistance compliance with GB/T 3956 standards.