OPGW cables are installed along high-voltage transmission lines, replacing or supplementing ground wires, with routes determined by tower positions, terrain, and network requirements.

Route Planning and Installation

OPGW (Optical Fiber Composite Overhead Ground Wire) is primarily installed on high-voltage transmission lines of 35 kV and above, serving both as a grounding wire and a fiber-optic communication medium for utilities and third-party networks . The full route of an OPGW cable is determined by:

• Transmission line layout: The cable follows the path of existing or newly constructed towers, spanning from substation to substation.
• Tower spacing and access: Distances between towers, terrain, and accessibility influence drum lengths and splice locations .
• Obstacles and crossings: Roads, railways, rivers, and other utilities are considered to ensure safe installation and maintenance.
• Splice points: Optical splices are placed at intervals based on maximum cable length, tower access, and network design .

Cable Types and Route Considerations

OPGW cables come in several constructions:

• Central Tube Type (OPGW C/CA): Fibers housed in a central stainless steel tube, protected by aluminum or steel layers .
• Aluminum Pipe Type (OPGW AP): Fibers inside a PVC and aluminum pipe for both protection and conductivity .
• Stranded Type (OPGW S): Fibers in aluminum tubes with more empty space, suitable for longer spans . The choice of cable type affects mechanical performance, tensile strength, and resistance to environmental factors like wind, ice, and lightning .

Installation Procedure

Installation follows strict procedures to protect the optical fibers:

• Survey and planning: Determine drum lengths, tower positions, and splice locations .
• Transport and handling: Drums are transported vertically, secured to prevent slackening, and carefully unloaded .
• Pulling and tensioning: Specialized equipment such as pullers, tensioners, swivels, and anti-twisting counterweights are used to string the cable along towers .
• Splicing: Fusion splicing is performed at designated points using closures that protect fibers from environmental stress .
• Final testing: Optical transmission characteristics are verified, and the system is certified for operation .

Summary

While the exact full route of OPGW cables is not publicly disclosed due to security and operational reasons, the route generally follows the high-voltage transmission line corridor, with careful planning for tower spacing, terrain, and splicing points. The installation ensures that the cable provides both grounding and reliable fiber-optic communication across the entire transmission network .