High-voltage Power Distribution Line Connection: Detailed Explanation Of The Design Of Aluminum Alloy Material And Bolt-type Tension Clamps

On the terminal towers or tension poles of overhead power lines, the fixing and tension transmission of conductors rely on high-quality hardware. As a key component of overhead power distribution lines, the physical structure and material selection of the bolted type strain clamp directly affect the stability of line operation. Through in-depth analysis of typical models such as the NLL series, technicians can more intuitively understand its operating mechanism.

Core Components and Material Construction

The main body of the bolt-type tension clamp is typically manufactured using high-strength aluminum alloy through a die-casting process. This material possesses excellent oxidation resistance, maintaining structural integrity for extended periods even under complex outdoor climates. The aluminum alloy shell features a smooth conductor groove with precisely calculated curvature to match the bending radius of conductors of different specifications.

In addition to the aluminum body, the entire system includes the following components:

• U-bolts: Made of hot-dip galvanized steel, providing the necessary clamping load.
• Pressure plates: Cooperate with the body to evenly compress the conductor within the groove.
• Flat washers and spring washers: Prevent fasteners from loosening due to line vibration.
• Hexagonal nut: Used with bolts to complete the final locking and fixing.

Force Distribution Analysis of Bolt-Type Tension Clamps

During installation, the conductor is placed in the groove of the aluminum alloy body, and the normal force generated by the tightening bolts locks the conductor in place. The gripping force of this connection method typically needs to reach more than 95% of the conductor's rated calculated breaking strength.

Local compressive stress adjustment

Since dead end strain clamp is fixed by the tightening pressure of bolts, the design of the contact surface between the pressure plate and the body is crucial. Aluminum material has a certain degree of ductility, allowing for slight deformation under pressure, thereby increasing the contact area with the conductor, reducing the compressive stress per unit area, and minimizing physical damage to the outer aluminum strands of the conductor.

Resistance Distribution Mechanism

The tightening force provided by each set of bolts forms a stepped distribution in the longitudinal direction. Bolts closer to the guy wire end bear the main anti-slip task, while bolts further away from the direction of force play a supporting stabilizing role. This distribution logic can balance the instantaneous impact force on the line under wind deflection or icy/snow loads.

Specifications and Technical Matching

Selecting the appropriate bolt-type tension clamp must be based on the nominal diameter of the conductor. Common NLL series clamps are divided into different specifications according to their application:

For aluminum stranded wire or steel-cored aluminum stranded wire, using bolted dead end clamp aluminum alloy can eliminate the risk of electrochemical corrosion. In practice, wrapping the wire contact points with aluminum sheathing tape can further improve contact performance through physical padding.