OPGW optical cable is also called optical fiber composite overhead ground wire. OPGW optical cable OPGW optical cable places the optical fiber in the ground wire of the overhead high-voltage transmission line to form the optical fiber communication network on the transmission line. This structure has the dual functions of ground wire and communication, and is generally called OPGW optical cable. The installation design of OPGW should consider the coordination with wire stress, sag and insulation gap, and its load should not exceed the allowable range of existing towers and foundations. Therefore, the characteristic curve should be calculated according to the main technical parameters of the selected OPGW, and the layout, outline and installation drawings of the junction box, various hardware and accessories should be designed in combination with the actual engineering. Extended reading: How do OPGW cable manufacturers ensure the quality of optical cables
OPGW optical cable installation structure design considerations
1. Treatment of initial elongation
For the treatment of the initial elongation of the OPGW, the cooling method can be used, that is, the aluminum-steel ratio of the OPGW is reviewed, and the initial elongation is treated with reference to the cooling value of the similar wire or ground wire.
2. Design of anti-vibration measures
Among the fittings used by OPGW, the tension clamp is of pre-twisted wire type, and the suspension wire clamp is equipped with pre-twisted wire and rubber gasket. These two types of fittings have certain anti-vibration capability. In order to further strengthen the anti-vibration capability, it is possible to consider installing an anti-vibration hammer, which is generally calculated according to the span:
When the span is less than or equal to 300M, install an anti-vibration hammer;
When the span is >300M, install two anti-vibration hammers.
3. Problems that should be paid attention to in the construction and erection of OPGW
The construction and erection of OPGW is different from ordinary steel strands. Care should be taken to prevent permanent damage to avoid affecting the performance of the optical fiber in the future, and should focus on: OPGW torsion, micro-bending, local radial pressure outside the clip and pollution to the optical fiber . Therefore, in the construction stage, the following effective measures should be taken to solve it:
(1) Prevent OPGW from twisting
Install counterweight and anti-twist device on the board and tightening clamp;
Adopt special double-groove pulley;
Tension line machine with double winch;
(2) Prevent and reduce the microbending and stress of OPGW
No acute angles are allowed (minimum bending radius is 500mm); the diameter of OPGW cable reel should not be less than 1500mm;
The diameter of the pulley should be more than 25 times the diameter of the OPGW, generally not less than 500mm; the inner side of the pulley should have a nylon or rubber lining to prevent scratching the surface of the OPGW;
Appropriate pulling wire and pay-off fittings;
Specify the maximum coil length of OPGW to be 6000M to prevent the number of times the pulley is overrun;
The line rotation angle of the continuous pay-off is limited to ≤30°. In a tension section of the pay-off, the OPGW direction after the corner should be in the shape of "C";
(3) Control of pay-off tension:
Adopt hydraulic tension pay-off and tractor with tension release device;
Limit pay-off speed ≤ 0.5 m/s;
(4) Prevent fiber pollution
In the construction and erection of OPGW, attention should be paid to encapsulating the ends;
Finally, we need to remind everyone that before the OPGW arrives at the site, before the erection, after the completion of the erection and the optical fiber connection and the completion of the entire line construction, the OPGW fiber attenuation acceptance test should be carried out on site in time.
