Causes Of Failure Of Bolt-type Tension Clamps Leading To Conductor Displacement

In power line structures, bolted type strain clamp serves to fix the tension of the conductor and also acts as a connector to transfer tension from the conductor to the tension string or tower. Under the combined action of operating loads and environmental stresses, the preload of the clamp bolts decays, causing overall gripping force degradation. This alters the contact state between the conductor and the clamp, leading to gradual micro-movement of the conductor. Accumulated micro-movement manifests as conductor slippage.

Contact Force Changes and Conductor Movement

Changes in clamping force directly affect the friction interface between the clamp and the conductor. In the initial stage of implementation of dead end strain clamp, the initial tension provided by the bolts maintains the frictional resistance between the conductor and the clamp, preventing the conductor from sliding under load. With prolonged operation or repeated thermal expansion and contraction cycles, the bolt preload may gradually release, reducing clamping friction and decreasing the interface pressure between the conductor and the clamp, leading to a tendency for localized slippage and eventually conductor slippage.

Stress Cycling and Degradation of Bolted Connections

The connection point of clamp bolted dead end clamp is essentially a bolt-nut system, where the load is primarily due to friction and mechanical locking. Stress cycles, vibrations, and temperature fluctuations in high-voltage lines can create fatigue stress at the bolt-clamp contact surface. With prolonged operation, fasteners and threads may experience creep, wear, or preload decay, reducing the clamp's overall constraint on the conductor.

Factors Inducing Conductor Misalignment

• Bolt Thread Wear: Repeated loads during long-term operation lead to a gradual loss of thread preload.

• Uneven Contact Surface: Installation or load variations cause uneven stress distribution on the contact surface.

• Environmental Impacts: Environmental factors such as temperature differences and humidity affect the stiffness and friction coefficient of fittings.

Engineering Impacts and Operational Risks of Conductor Misalignment

Although "conductor misalignment" may appear as a slight conductor displacement, it often reflects dynamic changes in the overall tension balance of the line. If a bolt-type tension clamp fails at a critical node, its reduced conductor holding capacity can spread to nearby connection points, affecting line geometry and insulation gaps through tension redistribution, ultimately increasing the risk of line failure.