OPGW optical cable overhead line construction method

OPGW installation involves careful planning, tension stringing, tower attachment, fiber splicing, and rigorous safety measures to ensure both electrical grounding and optical communication functionality.Pre-Installation Planning

Before installation, a detailed engineering plan is essential. This includes surveying the transmission line route, selecting the appropriate OPGW cable type (single-mode or multi-mode fibers, fiber counts from 12 to 144), and determining drum lengths based on tower spacing, terrain, and obstacles such as roads or railways . Design drawings are provided to the engineering team, which prepares an operation guide including spanning charts, schedules, and pre-reserved splice locations . Mechanical properties, transmission performance, and splice loss parameters must be verified before installation .

Equipment and Tools

Key equipment includes tension machines, pullers, pay-off machines, pulleys, anti-torsion devices, swivels, traction nets, sag boards, theodolites, hand chain blocks, and communication devices for coordination . Safety gear such as helmets, belts, warning signs, and protective nets is mandatory .

Installation MethodologyTension Stringing

Tension stringing is the preferred method for long spans. The cable is pulled using a tensioner and puller to maintain controlled tension, preventing damage to the optical fibers . Maximum stringing tension should not exceed 20% of the cable's rated breaking strength, and sag is carefully monitored. The cable is threaded through sheaves and bull-wheel tensioners, with anti-rotational devices used for cables with un-stranded central tubes .

Static Stringing

Static stringing involves pulling the cable at lower speeds using a winch. It is simpler but more prone to abrasion and is generally used for shorter spans or less critical installations .

Tower Attachment

OPGW is attached to transmission towers using suspension clamps for tangent towers and tension clamps for angle or dead-end towers . Clamps must be torqued correctly to prevent slippage while allowing thermal expansion. Support ropes may be used at angle structures to maintain proper cable alignment .

Fiber Splicing and Testing

Fiber optic adapters and splice boxes are installed at tower intervals to facilitate splicing. Optical attenuation and transmission tests are conducted to ensure signal integrity . Care is taken to maintain the minimum bending radius and avoid twisting or kinking of fibers during installation .

Transport, Handling, and Storage

OPGW drums must be transported vertically with ends secured to prevent slackening. Drums should not be thrown or rolled uncontrolled, and storage should avoid laying drums on their sides . Visual inspection for damage and verification of reel tags is performed before installation .

Safety Considerations

Safety is critical due to the dual function of OPGW as a ground wire and communication medium. Workers must use personal protective equipment, follow proper rigging procedures, and account for environmental factors such as wind, ice, and lightning . Communication between teams is maintained via radios or intercoms during stringing operations .

Post-Installation

After installation, the cable is inspected for mechanical integrity, proper tension, and optical performance. Any splices are tested, and documentation is completed for acceptance and certification . Regular maintenance checks are recommended to ensure long-term reliability. By following these steps, OPGW can be safely and effectively installed, providing both lightning protection and high-speed data transmission for power grid monitoring and communication.