Opg optical cable tension string

OPGW cables should be stringed under controlled tension, typically not exceeding 20% of the cable's rated breaking strength, using specialized tensioning equipment to prevent fiber damage and ensure proper sag.

Tension Guidelines

During OPGW installation, the maximum stringing tension should generally not exceed 20% of the rated breaking strength (RBS) of the cable, and it is usually maintained at about half of the maximum sagging tension to avoid overstressing the fibers . Tension is always measured at the tensioner side, and care must be taken to prevent kinking or bending the cable beyond its minimum bending radius, which could damage the optical fibers .

Stringing Methods

There are two primary stringing methods:

• Tension Method: The OPGW is kept under controlled tension throughout the installation. A pilot line is first pulled through traveler sheaves, and the cable is then pulled using a tensioner and puller set that maintains a constant load. This method prevents ground contact, reduces fiber abrasion, and ensures uniform sagging. It is preferred for long spans, high-voltage lines, and challenging terrains .
• Slack Method: The cable is laid on the ground before being lifted into the sheaves. This method is simpler and faster for short spans or isolated sections, but it carries a higher risk of fiber damage due to ground contact and is not recommended for rough or urban areas .

Equipment and Safety

Proper installation requires specialized equipment, including:

• Tension machines and pullers with tension indication and limiting devices to maintain constant load .
• Pulleys and sheaves with grooves at least equal to the cable diameter and a minimum bending radius of about 20 times the cable diameter to prevent damage .
• Anti-torsion devices, swivels, and pulling grips to avoid twisting and fiber stress .
• Safety gear such as helmets, belts, grounding wires, and warning signs to protect personnel and prevent induced voltages from nearby energized lines .

Installation Considerations

• The cable should travel through the lowest part of the sheave groove to prevent riding out or excessive twisting .
• Reels should be transported vertically with ends secured to prevent slackening .
• Pulley grooves should be lined with elastic buffer layers to reduce abrasion and prevent surface damage .
• Communication between puller and tensioner crews is essential, often using two-way radios or fiber-based headsets . Maintaining proper tension and using the correct equipment ensures mechanical safety, fiber integrity, and efficient installation, reducing labor and minimizing the risk of damage during OPGW stringing.