1. Application in Icing Lines
For lines in heavily iced areas, icing significantly increases the vertical and horizontal wind loads on the conductors. It also generates longitudinal tension due to uneven icing, asynchronous de-icing, and even galloping.
When designing overhead transmission lines in icing areas, suspension clamps are required to have greater gripping force on the conductors to resist the various adverse effects of heavy icing. Pre-stranded suspension clamps, with their structure featuring a high-performance rubber pad in direct contact with the conductor at the center and long pre-stranded wires wound around the rubber pad and conductor surface, offer advantages such as no stress concentration points and high gripping force. Taking the AGS5133 pre-stranded suspension clamp as an example, according to the experimental report (No.: K111S30663) from the China Electric Power Research Institute, this model of pre-stranded suspension clamp has a gripping force of 65kN, fully meeting the gripping force requirements for conductors in heavy icing areas, making it very suitable for heavy icing lines.
In addition, pre-stranded anti-galling whips can be appropriately used on icy lines. These mainly consist of three parts: a gripping section, a support section, and an anti-galling section. The anti-galling whip continuously changes the dynamic shape of the cable under wind conditions, disrupting the airflow of the conductor and thus preventing conductor galloping. Furthermore, since the anti-galling section is not fixed to the conductor, there is relative movement or even slapping between it and the conductor when the wind blows, which can provide a certain degree of de-icing effect in light icing.
2. Application in Long-Span Lines Long-span transmission lines are characterized by large spans and typically use lightweight, small-section, and high-mechanical-strength conductors, such as steel stranded wire or aluminum alloy stranded wire. A major drawback of these conductors is the difficulty in eliminating micro-wind vibrations. According to line operation data and research, micro-wind vibration is a primary factor causing conductor fatigue loss.
Traditional suspension clamps are bolt-type clamps, which work by compressing the conductor with bolts to maintain the clamp's grip. This type of clamp is relatively simple to design and manufacture, has low cost, and is widely used. However, statistical data from both domestic and international sources show that almost all conductor fatigue damage occurs at the contact point between the conductor and the clamp. Under the action of traditional clamps, the conductor in the contact area is prone to high dynamic and static compressive stresses. Pre-stranded suspension clamps, through a novel structural design concept... This design allows the clamp to provide sufficient gripping force on the conductor without requiring bolts to act on it. This increases the contact area between the conductor and the clamp, eliminating stress concentration points and effectively distributing the static pressure of the clamp over a sufficiently large area. Furthermore, the pre-twisted wire wound around the conductor surface significantly improves the bending stiffness of the contact area and reduces dynamic stress.
After undergoing tens of millions of vibration fatigue cycles under the same conditions, both conventional bolt-type suspension clamps and pre-twisted suspension clamps showed significant conductor breakage in the former, while the latter showed no damage. This demonstrates that pre-twisted suspension clamps possess strong fatigue resistance and can effectively reduce fatigue losses in long-span transmission lines.
3. In lines with large elevation differences... Applications: Pre-stranded suspension clamps come in single-point and double-point types. Single-point clamps typically accommodate conductor suspension angles less than 30°, while double-point clamps can be used up to 60°. For transmission lines located in mountainous areas, pre-stranded suspension clamps can meet the requirements for suspension angles with large elevation differences. Furthermore, due to the large vertical span and load at the suspension point in lines with large elevation differences, pre-stranded suspension clamps can distribute concentrated stress and provide greater grip on the conductor compared to ordinary clamps. Therefore, pre-stranded suspension clamps are more advantageous for lines with large elevation differences.
Additionally, because of the large elevation difference angle in lines with large elevation differences, traditional vibration damper fixing methods are prone to slippage when conductor creep occurs. Pre-stranded vibration dampers, using pre-stranded wires to tightly bind the damper to the conductor, effectively overcome slippage while simultaneously providing vibration damping.
