Abstract: To address the problem of harsh engineering site environments, which make fault detection and testing difficult, this paper uses the classic cable loop impedance calculation formula to analyze the variation law of cable line impedance under different laying axis spacing conditions, and then calculates the voltage required for the connected transmission equipment when a certain current is passed through the cable. A trial cable with an insulated conductor core is then fabricated for experimental verification to identify the relationship between laying spacing and reactance, ultimately determining the equipment parameters needed to achieve higher currents. The results show that the larger the cable laying axial spacing, the greater the impedance; to pass the same current through the cable, a higher output voltage is required. When the cable laying axial spacing is 80.9 mm, the average error between the calculated and actual values is less than 5%. When the cable spacing increases to 200 mm, the average error decreases to 2%, and when the spacing further increases to 300 mm, the average error further decreases to 1.25%. For a cable with a cross-section of 2 500 mm², when a current of 4 000 A is passed through it, the required power of the step-up transformer is 56 kW, the power of the voltage regulator is 70 kW, and the turns ratio of the step-up transformer is 15.7.