Guide to Selecting Underground Power Transmission Cables

In electrical infrastructure development, underground power transmission plays a vital role. XLP USE (Cross-Linked Polyethylene Underground Service Entrance) cables serve as the primary medium for underground power transmission, with their performance directly impacting the safety, stability, and reliability of power systems. This article provides engineers, electrical contractors, and related professionals with a comprehensive selection guide for XLP USE cables, analyzing their characteristics, applications, and selection considerations to facilitate informed decision-making.

XLP USE cable, fully known as Cross-Linked Polyethylene Insulated Underground Service Entrance cable, is specifically designed for underground power transmission. Its core advantages include exceptional voltage resistance, oil resistance, gas corrosion resistance, and weather resistance, with black-jacketed USE cables offering particularly outstanding UV resistance. These properties make XLP USE cables an ideal choice for industrial applications requiring high water resistance.

• Exceptional Electrical Performance: XLP USE cables typically have a rated voltage of 600V, meeting most low-voltage power transmission needs. Their cross-linked polyethylene (XLPE) insulation material provides excellent electrical insulation properties, effectively preventing current leakage and ensuring safe, reliable power transmission.
• Superior Environmental Adaptability: XLP USE cables demonstrate outstanding resistance to high and low temperatures, moisture, and chemical corrosion, enabling long-term stable operation in harsh underground environments. Their UV resistance also makes them suitable for applications exposed to sunlight.
• Versatile Applications: XLP USE cables can serve as RHH (Rubber Insulated High Heat-Resistant Wire) and RHW-2 (Rubber Insulated Heat and Moisture Resistant Wire) in both wet and dry industrial environments. This versatility allows them to meet diverse application requirements.
• Industry Standard Compliance: XLP USE cables typically comply with UL 854 standards, which rigorously specify performance, safety, and reliability requirements for underground service entrance cables. UL 854 compliance indicates certification by authoritative bodies, ensuring reliability.

XLP USE cables are often associated with RHW and RHH cables due to their interchangeable use in certain applications. Understanding these cable types aids in better XLP USE cable selection.

RHW cable is a rubber-insulated, heat- and moisture-resistant wire. The letters in its name represent specific properties: "R" denotes rubber insulation (typically XLPE or other synthetic rubbers), "H" indicates heat resistance (up to 75°C), and "W" signifies moisture resistance, allowing long-term underwater use.

RHW-2 cable is an upgraded version of RHW cable, with the primary difference being higher heat resistance (up to 90°C). Like RHW, it maintains moisture resistance for use in both wet and dry environments.

RHH cable is a rubber-insulated, high heat-resistant wire where "HH" denotes high heat resistance (up to 90°C). Unlike RHW cables, RHH lacks moisture resistance and is suitable only for dry environments.

XLP USE cables are widely used in various underground power transmission scenarios, including:

• Underground Service Entrance: Primarily transmitting power from transformers or distribution boxes to buildings or residences, their weather and corrosion resistance withstand harsh underground conditions.
• Underground Power Distribution: Used in constructing underground distribution networks for cities, industrial parks, and other areas, their high reliability and longevity make them ideal for this purpose.
• Industrial Applications: Widely employed in factories, mines, oil fields, etc., their oil, gas corrosion, and high-temperature resistance meet industrial environments' special demands.
• Commercial Applications: Suitable for commercial buildings like shopping centers, offices, and hotels, their safety and reliability ensure stable operations.

When selecting XLP USE cables, consider these factors:

• Conductor Material: Copper offers superior conductivity but higher cost; aluminum is lighter and cheaper but requires larger cross-sections for equivalent current capacity.
• Conductor Size: Determined by load current and installation method, following relevant electrical codes to ensure safe power transmission.
• Insulation Material: Typically XLPE, providing excellent electrical insulation, heat resistance, and chemical corrosion resistance based on environmental conditions.
• Jacket Material: Usually PVC or synthetic rubber, protecting insulation from mechanical damage, chemicals, and UV radiation depending on environmental requirements.
• Environmental Conditions: Temperature, humidity, chemical exposure, and UV radiation affect performance and lifespan; select cables suited to these factors.
• Standards and Codes: Ensure compliance with standards like UL 854, indicating certified reliability.

XLP USE cables come in copper and aluminum variants, each with distinct advantages:

Superior conductivity, higher current capacity, lower resistivity, and greater mechanical strength ensure durability, though at higher cost and weight.

Lower cost and weight facilitate easier installation and maintenance, but with reduced conductivity, higher resistivity, and lower mechanical strength requiring periodic maintenance to prevent creep.

Selection depends on balancing cost, performance, and application needs: copper for high current/reliability requirements with sufficient budget; aluminum for cost-sensitive, lower-current applications.

Proper installation and maintenance are crucial for long-term reliability:

• Installation: Follow electrical codes, maintain proper bending radius to avoid insulation damage, ensure secure connections, and protect from mechanical damage during laying.
• Maintenance: Regularly inspect insulation integrity, connection security, and installation compliance; repair or replace damaged cables promptly.

As a critical component of underground power transmission, XLP USE cable selection requires careful consideration of multiple factors. By thoroughly understanding their properties, applications, and selection criteria, professionals can choose appropriate cables to ensure safe, stable, and reliable power system operation. Whether for industrial, residential, or commercial use, XLP USE cables deliver exceptional performance within their specified ranges, providing dependable power transmission solutions.