OPGW combines an optical core with a structural conductor, so it is far more sensitive to mechanical abuse than a plain conductor. Over long spans and sharp bends, a moment of excess tension or a too-small sheave can crush the optical unit and turn a data link into scrap. Preventing OPGW cable damage during long-span installation depends on controlled tension and the right stringing equipment.
Where OPGW Damage Happens
Damage concentrates at three places: the pull during long spans, the wrap around every sheave, and the transition at the tensioner. Because the optical fibres sit inside the strands, a localised crush that leaves the outer conductor looking fine can still break a fibre.
Control the Pulling Force
Long spans multiply tension quickly. The puller must be able to hold a steady, low load without stalling or jerking, and its rating must exceed the calculated tension with margin. A machine with a defined relationship between pull and speed lets the operator keep speed low near design tension. The Galaxy GX90TP is representative:
Reference Specification — Stringing Puller
| Parameter |
Value |
| Maximum pull |
90 kN |
| Max intermittent tension |
90 kN |
| Trial traverse diameter |
40 mm |
| Total weight |
4600 kg |
| Boundary dimension |
4700 × 2300 × 2700 mm |
Match the Tensioner to the Span
On the front end, the tensioner holds back the OPGW so it pays off under controlled tension. Its sustained rating matters more than its peak, because long spans are pulled slowly for extended periods:
| Parameter |
Value |
| Max intermittent tension |
2 × 70 kN |
| Max sustained tension |
2 × 65 kN |
| Max pay-off speed |
5 km/h |
| Total weight |
7500 kg |
| Boundary dimension |
4700 × 2300 × 2700 mm |
Temperature, Sag and Design Limits
Long spans are also the most sensitive to temperature and sag. The conductor and OPGW expand in heat and contract in cold, so the same span carries different tension at dawn and at midday. Design limits set a maximum tension and a minimum ground clearance at the sag point. Installation crews should therefore pull to the design tension for the measured conductor temperature, not to a fixed figure, so the line ends within both limits. Keeping the pull slow and steady under these conditions protects the optical unit as much as the conductor.
Installation Rules for Long Spans
- Calculate tension for the full span including every bend before the pull.
- Keep pulling speed low as tension approaches the design value.
- Use sheaves sized for the OPGW diameter so fibres are never over-bent.
- Never allow a slack-to-tight shock; maintain steady tension throughout.
- Protect the cable at the tensioner with a matched groove.
- Inspect for jacket scoring and any bend tighter than the minimum radius.
The 9 T transmission line stringing equipment provides steady pull control, while the 2 × 70 kN hydraulic tensioner holds the OPGW back under constant tension. The complete Stringing Equipment range pairs pullers and tensioners for matched, gentle pulls.
FAQ
What is the main risk to OPGW over long spans?
Excessive or shock tension. Even a brief overload can break fibres without visibly marking the outer conductor.
Does span length change the machine choice?
Yes. Longer spans need more pulling capacity and finer low-speed control, so the puller and tensioner must be matched to the calculated tension.
How can I tell if OPGW was damaged during the pull?
Optical time-domain testing after installation reveals fibre breaks. Field checks for jacket scoring and tight bends catch mechanical causes earlier.
Get a Selection Recommendation
Give us your span lengths, OPGW type, tower geometry and ambient conditions, and we will recommend matched puller and tensioner ratings for a controlled long-span install.
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