The underground electrical power cables involved in this article include Vvg-Ng models 4X25, 4X35, 4X50, and 4c 25mm² Tr XLPE insulated pure copper underground electrical power cables. These products occupy an important position in the field of underground power transmission due to their excellent performance and competitive prices.​ In terms of specification parameters, "4X" in Vvg-Ng 4X25, 4X35, 4X50 indicates that the cable contains 4 conductors, and the numbers following represent the cross-sectional area of each conductor, which are 25mm², 35mm², and 50mm² respectively; 4c 25mm² means the cable has 4 conductors, each with a cross-sectional area of 25mm². A larger cross-sectional area means a stronger current-carrying capacity, which can meet the power transmission needs of different powers. For example, the 4X25mm² cable is suitable for medium-power underground power transmission, such as the underground power distribution system in residential areas; the 4X50mm² cable can be used in the underground main transmission lines of large industrial plants to ensure the power supply of high-power equipment.​ These cables use Tr XLPE (cross-linked polyethylene) as the insulation material. XLPE insulation has excellent electrical performance, with high insulation resistance and good corona resistance, which can effectively reduce energy loss during power transmission and improve transmission efficiency. At the same time, its temperature resistance is excellent, and it can work stably in a higher temperature environment, adapting to complex temperature changes underground. The conductor is made of pure copper, which has excellent conductivity, ensuring the stability and reliability of power transmission, reducing heat generated due to excessive resistance, and lowering potential safety hazards.​ As underground power cables, they have good corrosion resistance and mechanical strength. The underground environment often has erosion factors such as chemical substances and moisture in the soil, and this series of cables can resist these erosions, ensuring long-term stable operation. Their mechanical strength is sufficient to withstand external pressures during underground laying, such as the weight of the soil and mechanical impacts during construction.​ In terms of application scenarios, these cables are widely used in urban underground power grid construction, underground power distribution in industrial parks, underground power transmission in residential communities and other fields. Whether it is the power main line under urban main roads or the underground cables connecting various production workshops in industrial parks, they can perform excellently, ensuring safe and efficient power transmission.​ In addition, this series of cables also has a very competitive price advantage. On the premise of ensuring product quality and performance, its price is more attractive than similar products, which can save costs for engineering projects and improve cost performance. For large-scale power construction projects, choosing such cables can not only meet the power transmission needs but also effectively control the project cost.​ To sum up, Vvg-Ng 4X25, 4X35, 4X50 and 4c 25mm² Tr XLPE insulated pure copper underground electrical power cables, with their various specifications, excellent materials, outstanding performance and competitive prices, have become ideal choices for underground power transmission, providing reliable power support for various underground power projects.