OPGW Optical Cable Laying Requirements

OPGW cables are typically installed on top of power line towers using the tension pay-off method, with careful handling to protect the optical fibers and ensure proper mechanical and electrical performance.

Overview of OPG

W InstallationOPGW (Optical Ground Wire) serves a dual purpose: it functions as a ground wire for power lines and as a fiber optic communication medium. Installation generally follows the same principles as traditional aerial power lines but requires additional care due to the optical fibers inside the cable.

Preparation

Before installation, a detailed engineering plan is prepared, including: Route survey and determination of drum lengths based on tower positions, access, and obstacles. Splice planning to ensure joints are positioned optimally along the line. Equipment preparation, including tension machines, pullers, pay-off machines, pulleys, anti-twisting devices, and safety gear such as helmets, belts, and warning signs.

Cable storage and handling, ensuring drums are kept vertical, protected from moisture, and inspected for damage before installation.

Laying Method

Tension Pay-

Off Method: The cable is pulled from the drum using a tensioner to maintain proper sag and avoid abrasion on the ground. This method reduces physical labor and ensures the cable hangs correctly between towers. Reeving and Stringing: The OPGW is threaded through sheaves, bull wheels, or tensioners according to the cable lay direction (left-hand or right-hand lay).

Care is taken to avoid kinking or twisting the strands, which could damage the optical fibers. Angle Structures: At tower angles, support ropes may be tied to keep the cable suspended and prevent excessive twisting or riding out of the traveler. Sag Control: Maximum stringing tension is typically limited to 20% of the rated cable strength, and sag is carefully monitored to prevent overstressing the cable.

Splicing and Termination

Splice locations are pre-determined based on cable length and tower spacing. Optical fiber splices are performed with care to minimize loss and maintain transmission performance. Termination points are installed at substations or generator rooms, following the detailed engineering plan.

Standards and Recommendations

Installation should comply with IEEE standards (1138-2008, 524-1992) and ITU-T L. 151, which provide guidance on handling, stringing, and jointing of OPGW cables. Special attention is given to environmental factors such as wind, ice, temperature variations, and lightning, which can affect cable tension and stability.

Safety and Handling

Use of cranes, forklifts, and proper lifting techniques is essential to prevent damage to the cable and ensure worker safety. Protective measures include anti-torsion devices, proper drum orientation, and adherence to minimum bending radius for optical fibers. By following these procedures, OPGW cables can be installed efficiently while maintaining both mechanical integrity and optical performance.