High-voltage terminations are critical components in electrical power systems, particularly in medium—and high-voltage applications. They connect or end high-voltage cables safely, ensuring that electrical insulation is maintained and preventing potential hazards such as arcing or electrical failures. These terminations are essential for the reliable operation of power distribution networks, substations, and other high-voltage equipment.
What Are High-Voltage Terminations?
High-voltage terminations are devices designed to manage the electrical stress at the end of a high-voltage cable. They ensure that the cable’s insulation is not compromised and the system remains safe and operational. Without proper terminations, the exposed end of a high-voltage cable could become a weak point, leading to insulation breakdown, arcing, or other failures.
High-voltage cables are manufactured to exact specifications to withstand mechanical and electrical stresses. Similarly, terminations must also meet precise standards to ensure they can handle the same stresses. If not correctly installed, terminations can become points of failure in the electrical system. For example, they protect against tracking (surface electrical discharges) and provide environmental sealing to prevent moisture ingress.
Types of High-Voltage Terminations
There are several types of high-voltage terminations, each designed for specific applications and environments:
Heat Shrink Terminations
These use heat-shrinkable materials to provide insulation and stress control. They are versatile and can be used for both indoor and outdoor applications. For instance, Prysmian’s heat shrink terminations for 11kV systems are noted for their ease of installation and excellent performance.
Cold Shrink Terminations
These do not require heat and are applied by stretching over the cable end. They are ideal for environments where heat application is not feasible or safe, such as hazardous areas. Nexans offers cold shrink terminations up to 42 kV.
Pre-Molded Terminations
Factory-made and available in fixed sizes offer a quick and reliable solution for terminating cables. Prysmian’s Click-Fit system is an example, designed for voltages up to 420 kV.
Outdoor Terminations
Specifically designed to withstand environmental challenges like rain, UV exposure, and pollution. They often include features like molded rain sheds to prevent water accumulation.
Indoor Terminations
Used in controlled environments where they are protected from external elements, such as inside substations or switchgear.
Each type ensures proper insulation, stress control, and grounding, preventing electrical stress from causing failures. The choice of termination depends on factors like voltage level, cable type, and environmental conditions.
Key Components and Functions
High-voltage terminations typically include several components:
Stress Control Layer manages electrical stress to prevent insulation breakdown.
Insulation Material provides dielectric strength, often using materials like silicone rubber or polymeric compounds.
Sealing System protects against moisture and environmental factors.
Cable Lug connects the cable conductor to equipment, suitable for copper or aluminium conductors.
Grounding System ensures safety by equalising electrical potential.
These components work together to maintain the integrity of the cable end, ensuring reliable performance under high electrical stress.
Applications and Standards
High-voltage terminations are used in various applications.
- Connecting cables to switchgear, transformers, or substations.
- Terminating cables in outdoor pole-mounted locations or indoor cable boxes.
- Supporting power transmission in renewable energy projects, such as offshore wind farms.
They are designed to meet international standards like IEC 60840, IEEE-48, and CENELEC HD 629.1, ensuring compatibility and safety across different systems. For example, TE Connectivity’s Raychem terminations comply with these standards and are tested for severe environmental conditions.
Leading Brands in Europe for High-Voltage Terminations
Europe is home to several leading manufacturers renowned for their expertise in high-voltage terminations. These companies provide high-quality, reliable products that meet stringent European and international standards. Below are the top brands:
Prysmian
Prysmian, an Italian multinational, is a global leader in the cable industry. They offer a wide range of high-voltage terminations, including:
- Coldfit Cable Terminations:
These are quick to install, suitable for 11kV systems, and ideal for outdoor use with molded rain sheds.
- Heatshrink Terminations
Provide excellent insulation and stress control for 11kV cables.
- Click-Fit System
A plug-and-play solution for voltages up to 420 kV, ensuring reliable connections.
Prysmian’s products are known for their durability, ease of installation, and performance in demanding environments.
Nexans
Nexans, a French company, is a major player in high-voltage cable accessories. Their offerings include:
- Heat Shrink Terminations
The MONO series provides stable performance up to 33kV with integrated stress control.
- Cold Shrink Terminations
Compact and easy to install, suitable for voltages up to 42 kV.
- Slip-On Terminations
Designed for indoor use, offering flexibility for various cable types.
Nexans is recognized for its innovation and commitment to customer service. It has a strong presence in Europe and beyond.
NKT
NKT, based in Denmark, specialises in power cable solutions and accessories. They provide:
- High-Voltage Terminations
Compatible with cables up to 245 kV, designed for both indoor and outdoor applications.
- Customised Accessories
Tailored to specific project needs, ensuring compatibility with various cable constructions.
NKT’s products are widely used in European power networks, particularly in renewable energy projects.
Tratos
Tratos, an Italian manufacturer, focuses on high-voltage cables and accessories. They offer:
- Heat Shrink Terminations
Suitable for voltages up to 72 kV, compliant with IEC 60840.
- Turnkey Solutions
- Including terminations for complete power transmission projects.
Tratos is known for its flexibility and ability to supply accessories for diverse applications that meet European standards.
Why High-Quality Terminations Matter
Choosing the right high-voltage termination is crucial for ensuring the safety and reliability of power systems. Poorly designed or installed terminations can lead to:
- Insulation Breakdown causing electrical failures or outages.
- Arcing posing safety risks to personnel and equipment.
- Environmental Damage can degrade cable performance.
Leading brands like Prysmian, Nexans, NKT, and Tratos offer products that are rigorously tested and certified to international standards. Their terminations are designed to withstand severe environmental conditions, provide long-term stability and durability and simplify installation, reducing the risk of human error.
For example, Prysmian’s Click-Fit system prevents cable movement due to thermo-mechanical forces, ensuring a fail-safe connection. Similarly, Nexans’ MONO terminations feature integrated stress control to minimise installation errors.
Considerations for Selection
When selecting high-voltage terminations, consider:
Voltage Level
Ensure the termination matches the cable’s voltage rating (e.g., 11kV, 33kV, or higher).
Cable Type
Compatibility with polymeric (XLPE, EPR) or paper-insulated (PILC) cables.
Environment
Outdoor terminations need weather resistance, while indoor ones prioritise compactness.
Installation Conditions
Cold shrink terminations are safer in hazardous areas where hot-working is restricted.
Consulting with manufacturers or distributors like Thorne & Derrick can help identify the best product for specific needs (Thorne & Derrick).
Conclusion
High-voltage terminations are indispensable for the safe and efficient operation of electrical power systems. They come in various types to suit applications, from indoor to outdoor environments. In Europe, brands like Prysmian, Nexans, NKT, and Tratos are at the forefront of providing high-quality terminations that meet the demands of modern power distribution networks. By understanding the role of these terminations and selecting products from trusted manufacturers, engineers can ensure the longevity and reliability of their electrical systems. Want to know more about my services? Click here.
