What is a Parallel Groove Clamp?

A parallel groove clamp is a robust mechanical connector that securely joins two electrical conductors, typically copper or aluminum cables, ensuring both electrical conductivity and mechanical stability. These clamps are essential in power transmission lines and overhead cable installations. In particular, aluminium parallel groove clamps are commonly used for aluminum conductors, providing a lightweight, corrosion-resistant solution for high-voltage electrical systems.

These clamps are designed with two parallel grooves to tightly grip the conductors, making them an efficient and versatile solution for electrical connections without permanently altering the conductors themselves. The bimetallic parallel groove clamp is especially useful when connecting copper and aluminum conductors, preventing issues like galvanic corrosion.

1. What is the Purpose of a Parallel Groove Clamp Connector?

The primary purpose of a parallel groove clamp is to establish a reliable electrical connection between two conductors while also providing mechanical stability. These connectors are designed to perform three critical functions:

1. Electrical Conductivity: Ensures minimal electrical resistance between the connected conductors, which is essential for efficient power transmission.

2. Mechanical Stability: The clamp ensures that the conductors stay securely in place, preventing any accidental disconnections due to external forces such as wind or vibrations.

3. Temporary or Permanent Connections: Used for both temporary repairs and permanent connections, offering flexibility across various electrical applications.

Parallel groove clamp

2. How Does a Parallel Groove Clamp Work?

A parallel groove clamp works by applying radial compression to the conductors, which induces microplastic deformation. This creates a highly reliable, 360° contact surface that facilitates low-resistance electrical conduction.

• Pre-tightening: The bolts are initially tightened to ensure the conductors settle into the grooves.

• Main Pressure: After reaching the specified torque (e.g., 35 N·m), the clamp applies significant contact pressure to the conductor, typically between 60-80 N/mm².

• Self-locking: The design includes a spring washer or wedge-shaped grooves that prevent loosening over time due to thermal expansion or vibrations.

• Electrical Conductivity: As the conductors settle into the grooves, metal-to-metal contact is achieved, effectively removing oxidation layers and enhancing conductivity.

SUNJ Parallel Groove Clamp Connector

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3. Parallel Groove Clamp Material

The materials used in parallel groove clamps play a crucial role in their performance. Here are the most common materials:

• Aluminum Blocks: Typically EN AW-1050A, offering excellent conductivity (61% IACS) and lightweight properties.

• Copper Blocks: Cu-ETP (C11000), with 100% IACS conductivity, ideal for copper conductors or copper-to-aluminum transitions.

• Bimetallic Blocks: Made by friction welding copper and aluminum, these connectors prevent galvanic corrosion and ensure high conductivity.

• Bolts: Stainless steel (A2-70) or HDG 8.8 steel, resistant to corrosion and high strength.

4. Pros and Cons of Parallel Groove Clamp

4.1 Advantages of Parallel Groove Clamp

1. Reliable Mechanical Connection: Tests show that the clamp can withstand over 95% of rated tensile strength, providing a stable connection under mechanical stress.

2. Enhanced Electrical Conductivity: Even under high current loads, the clamp maintains low contact resistance (≤ 15 µΩ), ensuring efficient power transmission.

3. Durability and Corrosion Resistance: These clamps are built to last, with some models providing over 30 years of service in harsh environments, such as coastal regions, with minimal corrosion.

4. Versatility: They can accommodate a wide range of conductor sizes (50-240 mm²) using interchangeable washers, making them suitable for various applications.

5. Simple and Efficient Installation: Installation is quick and does not require special tools, making it an efficient solution for both new installations and repairs.

6. Economical and Affordable: Compared to other methods like compression fittings, PG clamps offer a more cost-effective solution, reducing both material and labor costs.

4.2 Disadvantages of Parallel Groove Clamp

1. Limited Current Carrying Capacity: These clamps typically carry around 80% of the conductor’s rated current, which might necessitate de-rating or parallel connections for higher loads.

2. Creep Effect: Aluminum conductors may experience a creep effect over time, which reduces bolt tension. Regular maintenance is required to re-tighten the connections.

3. Increased Load: The weight of the clamp itself (0.3-1.0 kg) can add additional stress to large spans, especially in high-load applications.

5. Application of Parallel Groove Clamp

PG clamps are widely used in various electrical applications:

1. Overhead Transmission Lines: PG clamps are essential for connecting conductors in high-voltage power transmission systems. These clamps ensure a secure and efficient electrical connection, even in the harshest conditions. For more details on how PG clamps function in these environments, check out our overview of PG clamps, their types, and applications.

2. Wire Branches and Jumper Connections: PG clamps are used to branch main lines to transformers or other sections of the network. They are ideal for connecting power lines and ensuring minimal electrical resistance.

3. Cable Connectors: These clamps are often used to transition between overhead cables and insulated cable systems, especially in photovoltaic stations or other renewable energy installations. The versatility of PG clamps allows for a seamless connection between different types of cables and systems.

4. Connecting Different Metal Conductors: Bimetallic PG clamps are particularly effective in preventing corrosion when connecting copper to aluminum conductors. By using bimetallic PG clamps, you can ensure a reliable connection that prevents galvanic corrosion, which is often seen in copper-to-aluminum junctions.

6. How to Install Parallel Groove Clamp

Proper installation ensures that the PG clamp performs effectively and reliably. Here’s a step-by-step guide:

JBL H Aluminium PG Clamp Dimension drawing

1. Prepare the Necessary Tools and Materials: Ensure you have a torque wrench, steel wire brush, conductive paste, and safety gear.

2. Prepare the Conductors: Clean the conductor surfaces thoroughly and apply a thin layer of conductive paste.

3. Select the Correct Clamp Size: The clamp size should match the conductor’s diameter.

4. Position the Clamp on the Conductors: Place the conductors into the grooves, ensuring no cross-contact.

5. Tighten the Clamp Bolts: Use the torque wrench to tighten the bolts in a cross pattern, first with light torque and then to the final torque.

6. Inspect the Installation: Ensure there are no gaps between the conductor and the groove. Check the clamp is firmly in place.

7. Conduct Electrical Testing: Measure the contact resistance with a milli-ohmmeter to ensure the connection is solid.

8. Final Safety and Maintenance: Regularly inspect the connections, particularly in high-vibration environments.

7. Standards and Certifications

To ensure the highest quality and safety, parallel groove clamps must adhere to various international standards, such as:

• IEC 61238-1: Ensures the mechanical and electrical reliability of PG clamps in high-voltage applications.

• EN 50483-4: Applicable to overhead distribution connectors, including PG clamps.

• ASTM B977: Specifies tensile testing requirements for PG clamps.

• UL 486A/B: Essential for North American market compliance for PG clamp connectors.

• ISO 9001/14001: Certification for quality and environmental management systems.

8. Conclusion

In conclusion, parallel groove clamps are essential connectors for efficient and reliable electrical connections in transmission lines, overhead installations, and various other electrical systems. With their versatility, durability, and ease of installation, PG clamps are a go-to solution for both temporary and permanent connections. Whether using aluminium parallel groove clamps for aluminum conductors or bimetallic parallel groove clamps for copper-to-aluminum connections, these clamps are indispensable in modern electrical infrastructure.