Slack Span Dead End: Terminate Fiber Lines

A slack span dead end is a specific configuration of conductor arrangement and support. Its main purpose is to provide a secure termination point for the conductor. It does this and allows for some flexibility and movement in the conductor. Slack span dead ends work in areas were the line needs to make a sharp turn at end-of-line poles. The conductor anchors at the slack span dead end using hardware that allows movement. These hardware includes clamps, insulators or other fittings. A “slack span” refers to a short span of conductor that is not under significant tension. A dead end refers to a point in the transmission line where the conductor anchors firmly. It also marks the end of a section of the line and the conductor does not continue past that point in the same direction.

Benefits of using a slack span dead end

Using a slack span dead end provides several benefits that enhance the reliability, safety and maintenance of the system. It helps to reduce the tension on the support structure on either side of the river and allows for safer and more stable crossing. The following are the advantages of the slack span dead end.

1. Reduced tension on structures – the slack span dead ends reduce the tension exerted on supporting structures. This helps to reduce the risk of structural failure and preserves the integrity of poles.
2. Enhanced flexibility and adaptability – the dead ends provide flexibility to absorb movements caused by wind or thermal expansion. They work in areas where the transmission line needs to change direction and ensure the conductor can adapt to the new path without stress.
3. Improved maintenance and inspection – maintenance crews can access the conductors for repairs, adjustments or replacements.
4. Enhanced safety and stability – reduced tension reduces the likelihood of conductor breakage. The design can help reduce the risk of galloping in windy conditions.
5. Cost efficiency – the slack span dead ends reduce the load on structures and reduce wear on components. This can lead to lower ling-term maintenance costs.
6. Compatibility with various terrain – slack spans can manage the differences in uneven terrain. This is to provide a practical solution for line installation. They offer the flexibility to accommodate various line layouts.
7. Mitigation of mechanical loads – slack span dead ends distribute mechanical loads along the line. This is to reduce the impact of sudden load changes. They act as buffers against dynamic forces like wind and ice to help maintain the integrity of the line.
8. Ease of integration with existing systems – the dead ends ease the integration of new sections of transmission lines. This allows for smooth transition between different types of structures or conductor configurations.

Accessories used with a slack span dead end

Slack span dead ends need various accessories to ensure they function as intended and maintain the integrity of the system. The accessories ease secure anchoring, flexibility and protection of the conductors. Additionally, using these accessories helps engineers to ensure the slack span dead ends provide a secure, flexible and reliable means of support. The following are the accessories used with slack span dead ends.

• Dead end clamps – these aid in anchoring the conductors at the end of the slack span. Common types used include bolted dead end clamps, compression dead end clamps and wedge type dead end clamps.
• Insulators – these help to electrically isolate the conductor from the support structure. They include pin insulators, suspension insulators and strain insulators. These insulators prevent electrical conduction to the support structure and provide insulation.
• Guy wires and guy grips – these provide extra support and stability to slack span dead ends. They anchor the structure to the ground to ensure a firm attachment.
• Tensioning devices – these help to apply and maintain the correct tension in the conductor. Turnbuckles and tensioning devices allow for precise adjustment and apply the necessary tension.
• Vibration dampers – these mitigate vibrations caused by wind or other factors that can lead to fatigue and damage over time. Stockbridge dampers dissipates vibrational energy while spiral dampers reduce vibrational amplitude.
• Spacer and spacer dampers – they maintain the separation between many conductors in a bundle. It also prevents clashing and maintaining electrical performance.
• Preformed armor rods – their purpose is to protect the conductor from abrasion and mechanical damage at points of stress. They have a helical shape to wrap around the conductor to distribute stress and provide a protective layer.

Slack dead ends for ADSS cables

Slack span dead ends for ADSS cables have designs with specific characteristics to handle the unique requirements of the cables. The dead ends ensure the mechanical stability and longevity of the cables in different environmental conditions. Additionally, the design characteristics ensure the ADSS cables are securely supported and protected from environmental and mechanical stresses. The following are the characteristics of the slack span dead ends for ADSS cables.

• Flexibility and low tension – the dead ends have designs to maintain a lower tension in the ADSS cable compared to regular spans. The reduced tension allows for slight movements and prevents excessive stress on the cable.
• Secure and reliable anchorage – slack span dead ends provide a secure anchorage for the cable without damaging the fibers inside. The anchoring system has designs to avoid causing any mechanical damage to the cables outer sheath.
• Electrical insulation – the dead end components are from non-conductive materials. These materials prevent electrical interference since ADSS cables are all dielectric.
• Vibration and motion resistance – the dead ends incorporate vibration damping accessories. They are to mitigate the effects of wind-induced vibrations. The design accommodates movements due to the environmental factors.  
• Environmental durability – the dead ends are from materials that are resistant to environmental factors. These include UV radiation, extreme temperatures, moisture and chemical exposure.
• Ease of installation and maintenance – slack span dead ends have designs for straightforward installation. Their flexible design reduces the need for frequent maintenance and any repairs.
• Mechanical strength and load capacity – the dead ends are able to support the weight and tension of the ADSS cables. The dead ends can absorb and dissipate mechanical shocks to protect the cable. 
• Compatibility with ADSS cable – the dead ends have designs to match the physical and mechanical characteristics of ADSS cables.

Slack dead ends for OPGW cables

Slack span for OPGW cables are important in the design and installation of overhead transmission lines. OPGW cables combine the functions of grounding and communication. This is by integrating optical fibers within a conductive metal strand. Also, the dead ends ensure the safety, durability and effectiveness of OPGW cable installations. The following are the characteristics of slack span dead ends used for OPGW cables.

1. Reduced mechanical tension – slack span dead ends have designs to maintain a lower tension in the OPGW cable. The design allows them to distribute mechanical stress along the cable.
2. Strong and reliable anchorage – dead ends provide a secure anchorage for the OPGW cable using various components. The anchoring mechanisms have designs to avoid causing any physical damage to the cable’s conductive components.
3. Electrical insulation and conductivity – OPGW cables serve as both a grounding conductor and a communication medium. They help maintain the cable’s grounding function while ensuring the optical fibers are well protected.
4. Environmental resistance – components for slack span dead ends are from materials that can withstand environmental factors. They are also resistant to corrosion to prevent degradation.
5. Compatibility with OPGW cable design – the dead ends are able to meet specific physical and mechanical characteristics of OPGW cables. They ensure the cables are not bent beyond a specified maximum.

Testing slack span dead ends

Testing ensures the reliability and safety of overhead transmission systems. Proper testing ensures the dead ends are able to withstand environmental stresses, mechanical loads and electrical conditions without failure. Also, the tests verify that the dead ends provide secure anchorage, maintain cable integrity and contribute to the reliability. The following are the common tests for slack span dead ends.

• Tensile load tests – this is to verify the mechanical strength and lad bearing capacity of the slack span dead end.
• Vibration testing – this test is to assess the dead ends ability to dampen and withstand vibrations.
• Environmental testing – this is to check the performance of the dead end under various environmental conditions. This is including temperature extremes, humidity, UV exposure and corrosion.
• Mechanical fatigue testing – this is to simulate long-term mechanical stress and check the dead ends durability over time.
• Electrical testing for OPGW – this test is to ensure the slack span dead end for OPGW cables can handle electrical loads ad provide grounding.

Frequently asked questions