High-voltage cables are engineered to transmit electrical power over long distances at voltages typically above 1,000 volts AC. They are critical components in transmission and distribution networks and are designed to minimize energy losses and withstand harsh environmental conditions. In this article, we answer common questions regarding high-voltage cables, including:

• What cable is used for high voltage?
• What are the typical applications of high-voltage cables?
• What materials and insulation types are used in high-voltage cables?
• How do high-voltage cables differ in design compared to lower-voltage cables?

We also discuss related topics such as HV cable insulation and jointing, and offer a look at emerging technologies.

1. What Cable Is Used for High Voltage?

High-voltage cables typically refer to cables designed for voltages above 1,000 volts AC. They are constructed with several key layers:

• Conductor: Usually made of copper or aluminum (or aluminum alloys), with aluminum often favored due to its lighter weight and cost-effectiveness.
• Insulation: Common insulation materials include Cross-Linked Polyethylene (XLPE) and Ethylene Propylene Rubber (EPR). XLPE is widely used in medium (1–69 kV) and high-voltage (up to 380 kV AC) cables due to its excellent dielectric properties and thermal resistance.
• Shielding: High-voltage cables incorporate semi-conductive layers and metallic shields (typically copper tape or concentric drain wires) to equalize electrical stress and prevent corona discharge.
• Jacket: An outer protective layer (often made of PVC, PE, or sometimes even armored with metal) protects against mechanical damage and environmental factors.

2. Typical Applications of High-Voltage Cables

High-voltage cables are used in various settings, including:

• Power Transmission: Connecting power plants to substations over long distances (e.g., cables rated at 110 kV, 115 kV, 132 kV, or higher).
• Submarine and Underground Installations: For instance, HVDC cables in submarine projects or underground cables in urban areas where overhead lines are impractical.
• Industrial Applications: Supplying power to heavy machinery and large-scale industrial plants.
• Renewable Energy Projects: Transmitting electricity from wind farms, solar farms, and hydroelectric installations to the grid.

3. Key Materials and Insulation Types in High-Voltage Cables

The performance and durability of high-voltage cables are determined by their construction materials:

• Conductors:
  • Copper: Provides excellent conductivity and durability but is heavier and more costly.
  • Aluminum and Aluminum Alloys: Lighter and more cost-effective; frequently used in overhead and underground systems.
• Insulation:
  • XLPE (Cross-Linked Polyethylene): Favored for its excellent dielectric properties, resistance to thermal degradation, and suitability for high-voltage applications.
  • EPR (Ethylene Propylene Rubber): Offers high flexibility and good electrical insulation, suitable for dynamic or harsh environments.
• Shielding:
  • Semi-conductive layers and metallic shields (e.g., copper tape) help maintain uniform electric fields and reduce leakage currents.

4. Design Differences Between High-Voltage and Low-Voltage Cables

High-voltage cables have more complex designs compared to low-voltage cables, incorporating:

• Additional Insulation Layers: To handle high electrical stress and prevent breakdown.
• Multiple Shielding Layers: To equalize voltage stress and control leakage currents.
• Stricter Construction Standards: As outlined in IEC 60840 and IEC 60502, which specify insulation thickness, shielding requirements, and testing procedures.

Comparison Table: High-Voltage Cable Construction

5. Additional Related Questions

Q1: Can high-voltage cables be used in both AC and DC systems?

Answer:
Yes. High-voltage cables are designed for both alternating current (AC) and high-voltage direct current (HVDC) applications. For HVDC, special insulation and design considerations (such as different dielectric properties) are required. HVDC cables are often used for long-distance submarine transmission to minimize losses.

Q2: What are the main challenges in designing high-voltage cables?

Answer:
Challenges include managing high electrical stress, ensuring insulation integrity, preventing corona discharge, and withstanding harsh environmental conditions. Special attention is required for shielding and insulation thickness, as well as for jointing and termination methods to maintain safety and performance.
Reference:

Q3: How do emerging technologies like smart cables and superconducting cables affect high-voltage transmission?

Answer:
Smart cables integrate sensors for real-time monitoring, enhancing reliability and predictive maintenance. Superconducting cables, though still in developmental stages for widespread use, offer virtually lossless transmission and are especially promising for high-load, dense urban areas.
Reference:

Conclusion

High-voltage cables are indispensable for the modern electrical grid, enabling efficient and reliable transmission of large amounts of power over long distances. Their complex design—including robust conductors, advanced insulation like XLPE or EPR, and multiple shielding layers—ensures safe operation under high electrical stress. These cables are used in a range of applications from power plants to submarine installations, and emerging technologies like smart monitoring and superconductivity promise further improvements in efficiency and reliability.

For further details, visit:

• Southwire High Voltage Products
• EES Cable High Voltage Cables
• NKT High Voltage Solutions