XLPE insulated 4×70mm², 4×95mm², 4×185mm² aluminium multicore underground power cables are medium and low-voltage transmission products specially designed for underground laying scenarios. With the lightweight advantage of aluminium cores, temperature resistance of XLPE insulation, and multi-specification cross-sectional design, they are widely used in urban power grid transformation, industrial park power distribution, rural power grid upgrading and other fields, providing efficient and stable power transmission solutions for complex underground environments.​ In terms of structural design, all three types of cables adopt a 4-core aluminium conductor configuration, corresponding to three cross-sectional specifications: 70mm², 95mm², and 185mm². The conductors are made of high-purity aluminium (purity ≥99.7%) through a multi-strand compact stranding process, which not only reduces the overall weight of the cable (the weight of the aluminium core is about 1/3 of that of the copper core under the same cross-section), facilitating underground laying construction, but also reduces conductor gaps through the compacting process, improving conductivity, with a conductivity of over 37MS/m. In the 4-core design, 3 cores are phase lines and 1 core is a neutral line, adapting to the three-phase four-wire power distribution system, meeting the phase balance requirements of low-voltage power distribution, without the need for additional neutral line laying, simplifying the layout complexity of underground pipelines.​ The insulation and protection system is the core competitiveness of this series of cables. The insulation layer is made of cross-linked polyethylene (XLPE) material, and the thickness increases with the cross-section: the insulation layer thickness of 4×185mm² cable is 1.6mm-1.8mm, 4×95mm² is 1.4mm-1.6mm, and 4×70mm² is 1.2mm-1.4mm. After cross-linking treatment, XLPE forms a three-dimensional network molecular structure, with excellent electrical properties - insulation resistance ≥1000MΩ·km, breakdown strength ≥20kV/mm, and can operate stably for a long time under the rated voltage of 0.6/1kV. Its temperature resistance is outstanding, with a long-term working temperature of up to 90℃, and can withstand 250℃ high temperature during short circuits (within 5 seconds), far exceeding ordinary PVC insulation materials, and can adapt to temperature changes in the underground environment caused by load fluctuations. The outer sheath is made of high-density polyethylene (HDPE) or polyvinyl chloride (PVC), with thicknesses of 2.0mm-2.2mm (185mm²), 1.8mm-2.0mm (95mm²), and 1.6mm-1.8mm (70mm²) respectively, with excellent weather resistance, corrosion resistance and impact resistance, which can resist underground soil pressure, moisture, acid and alkali substances, and gnawing by rodents.​ In terms of performance parameters, all three cables meet the 0.6/1kV voltage level requirements, and the current-carrying capacity increases significantly with the increase of cross-section: the 4×185mm² cable has a current-carrying capacity of about 250A-270A when directly buried at an ambient temperature of 30℃, suitable for large-capacity power transmission; 4×95mm² has a current-carrying capacity of about 190A-210A, suitable for medium-load areas; 4×70mm² has a current-carrying capacity of about 150A-170A, suitable for small-scale power distribution. The bending radii are 12 times (185mm²), 10 times (95mm²), and 8 times (70mm²) the cable outer diameter respectively, with the minimum bending radii of about 280mm (185mm²), 220mm (95mm²), and 180mm (70mm²), facilitating turning and laying in narrow underground spaces. The overall weight per kilometer is about 650kg (185mm²), 500kg (95mm²), and 380kg (70mm²) respectively. The lightweight feature reduces the difficulty of construction hoisting.​ In application scenarios, 4×185mm² cables are often used in urban underground trunk lines, incoming cables of large industrial parks, connecting regional substations and distribution hubs, undertaking high-load power transmission tasks; 4×95mm² is suitable for power distribution in town centers and workshop trunk lines of medium-sized factories, balancing transmission capacity and cost; 4×70mm² is mostly used in rural power grid transformation, residential community branches and underground wiring of street lamp systems, meeting decentralized power demand. All three cables support direct burial, pipe threading, tunnel laying and other methods. In areas with high groundwater levels and strong soil corrosion, reinforced HDPE sheaths can be selected to further improve the protection level.​ In terms of construction and maintenance, the cable needs to undergo insulation resistance testing (≥1000MΩ) and appearance inspection before laying. For direct burial, a 100mm thick sand cushion should be laid and a warning board should be covered to avoid mechanical damage; cold-shrink accessories are used for sealing at joints to ensure waterproof and moisture-proof. In daily maintenance, the operating temperature of the cable can be monitored through a distributed optical fiber temperature measurement system, and the insulation status can be evaluated in combination with grounding resistance testing to early warn potential faults. Its designed service life is more than 30 years, which greatly reduces the replacement frequency and maintenance cost of underground cables.​ In summary, XLPE insulated aluminium multicore underground power cables, with their lightweight, high temperature resistance, strong protection and other characteristics, show significant advantages in the underground power distribution field, providing accurately adapted power transmission solutions for scenarios with different load levels, and are ideal choices for urban and rural power grid upgrading and industrial power distribution.