What is OPGW Cable?
OPGW Cable is short for Optical Fiber Composite Overhead Power Ground Wire. OPGW cable is placed in the ground wire of overhead high-voltage transmission lines to form the OPGW fiber optic cable communication network on the transmission lines. This structural form combines the dual functions of ground wire and communication.
Due to the characteristics of anti electromagnetic interference and light weight, OPGW optical cable can be installed on the top of transmission line towers without considering the best hanging position and electromagnetic corrosion issues. Therefore, OPGW has significant characteristics such as high reliability, superior mechanical performance, and low cost. This technology is particularly suitable and economical for new installation or replacement of existing grounding wires.
Fiber utilizes the difference in refractive index between the core and cladding materials to transmit light energy in optical fibers, which has become a major revolution in the history of communication. Fiber optic cables are lightweight and compact, and have been adopted by power systems to transmit dispatch calls, remote signals, relay protection, television images, and other information between substations and central substations. In order to improve the stability and reliability of fiber optic cables, foreign countries have developed a composite structure of fiber optic cables, transmission line phase conductors, overhead ground wires, and power cables. OPGW fiber optic cables are more reliable, stable, and reliable due to the wrapping of metal wires. The combination of overhead ground wires and fiber optic cables shortens the construction period and saves construction costs compared to using other methods of fiber optic cables. In addition, if aluminum clad steel wire or aluminum alloy wire is twisted into OPGW, it is equivalent to setting up a good conductor overhead ground wire, which can achieve various benefits such as reducing the potential supply current of transmission lines, reducing power frequency over-voltage, improving the interference and dangerous impact of power lines on communication lines, etc.
OPGW Cable Application
OPGW cables are mainly used on 500KV, 220KV, and 110KV voltage level lines. Due to power outages and safety issues, they are often used on newly built lines.
OPGW Cable Features
(1) High voltage exceeding 110kV lines with large spans (usually all above 250M);
(2) Easy to maintain, easy to handle for line crossing issues, and its mechanical characteristics can meet the requirements for large line crossings;
(3) The outer layer of OPGW is metal armor, which has no effect on high-voltage corrosion and degradation;
(4) OPGW requires power outages during construction, resulting in significant losses. Therefore, OPGW should be used in the construction of new high-voltage lines with voltages above 110kV;
(5) In the performance indicators of OPGW, the larger the short-circuit current, the more it is necessary to use good conductors for armor, which correspondingly reduces the tensile strength. However, under a certain tensile strength, to increase the short-circuit current capacity, the only way is to increase the metal cross-sectional area, resulting in an increase in cable diameter and weight, which poses a safety issue for the strength of the transmission tower.
Common OPGW structures
There are three main types: aluminum tube type, aluminum frame type, and stainless steel tube type.
Single layer central stainless steel tube OPGW
Structure Characteristic and Application
·Small cable diameter and short-circuit current capacity,light weight
·Obtaining appropriate primary fiber excess length within SUS tube
·The OPGW has a bit poor tensile,torsion and crush resistance performance
·Matching with GJ-35,GJ-50 and GJ-70 different ground wire
Two layer twisted stainless steel tube OPGW
Structure Characteristic and Application
·Bigger cable diameter and higher fiber count
·The best balance of mechank performance for the bigger RTS and fault current capacity
·Quantity of SUS OP-Unit could be 1.2 or 3(max at present)
·Optimum stranding design,making primary and secondary fiber excess length
·The stranded layer could be single,double layers or three layers,the stranded wire could be AS wires with/or AA and AL wires
Central aluminum clad stainless steel tube OPGW
Structure Characteristic and Application
·AL-covered SUS tube design increasing AL sectional area, the better fault current and lightning resistance performance
·Extremely good corrosion resistance
·Filling up the vacant cable diameter design of 11.4–13.5mm
·Used in the transmission line which specify the small cable diameter and bigger fault current
·Extremely corrosion condition,such as littoral,chemical areas
Twisted double-layer armor structure
Structure Characteristic and Application
·Compressing round AS wires as sector AS wires during stranding
·Increasing cable cross sectional area and fault current capacity at the same cable diameter
·Extremely increasing lightning resistant
performance for increasing the outer wires diameter at the same cable diameter
·Decreasing cable diameter at the same cable cross sectional area
Used in the transmission line which specifies the small cable diameter and bigger fault current
·Used in high lightning storm areas
OPGW Cable Fittings And Accessories
OPGW Suspension Clamp
Preformed twisted dead end suspension clamp is a metal fitting used to suspend ADSS OPGW cables on transmission towers, it will protect the optical cable from damage during installation and operation, and ensure minimal fiber deformation.
Component Parts
Inner layer twisted wire, outer layer twisted wire, rubber fixture, U-shaped hanging ring, cast aluminum clamp block, bolt, nut, washer, closed pin.
Technical features:
The double-layer structure provides greater protection for optical cables operating under long-term unbalanced loads, with excellent dynamic stress bearing capacity and improved grip strength;
Due to the large contact area, uniform stress distribution, and no stress concentration points, the stiffness of the cable installation point is enhanced, which provides good protection for the cable;
Has good dynamic stress bearing capacity and can provide sufficient grip strength (15% -20% RTS) to protect the safe operation of OPGW optical cables under unbalanced load conditions;
The structure is simple, easy to install, does not require special tools, and is maintenance free.
Application
This clamp can be used for 110KV and above power lines, and for installing optical cable lines on the same pole.
If the elevation angle of the line is less than 25 degree, will use 1 set suspension clamp, if greater than 25 degree, recommended to use double suspension clamps.
OPGW Tension Clamp
The fiber optic OPGW cable tension clamp evenly distributes radial pressure and transmits axial tension, ensuring safe and reliable grip without damaging the fiber optic cable.
Components:
Preformed twisted tension wire, wire guard wire (not included in small tension clamps), U-shaped hanging ring, heart-shaped connecting ring, extension rod, bolt, nut, washer, closed pin, etc.
Features:
Spray sandblasting on the inner and outer twisted wire walls to increase damping effect and provide good protection for the optical cable.
Due to the large contact area, uniform stress distribution, and no stress concentration points, it provides good protection for the cable.
The grip strength of the optical cable should not be less than 95% RTS of the optical cable, which is fully suitable for the needs of optical cable installation.
The selected material has strong corrosion resistance and aging resistance.
Simple structure, easy installation, no need for specialized tools, and maintenance free.
Application
Used for terminal towers, tension towers, towers with an angle (elevation) greater than 25 °, and connecting towers
Related Products
Preformed Dead Ends，OPGW splice box, OPGW Downlead Clamp,OPGW suspension clamp, Cable Storage Rack, Anti-shock hammer
FAQ
What is the purpose of OPGW cable?
OPGW fiber meaning Optical Fiber Composite Overhead Power Ground Wire, it is placed in the ground wire of overhead high-voltage transmission lines to form the OPGW fiber optic cable communication network on the transmission lines.
What is the difference between OPGW and ADSS cable?
Structural difference: ADSS (All Dielectric Self Supporting) optical cable is a type of all dielectric self-supporting optical cable, mainly suitable for suspension between power line towers, without the need for additional tower support. OPGW (Overhead Power Ground Wire) optical cable is a ground wire hung above the transmission line, which returns to the ground through the current of the transmission line.
What is the difference between OPGW and OPPC?
OPPC (Opticalphase Conductor, abbreviated as OPPC) is a new type of optical cable specifically designed for power communication systems. It is a fiber optic cable that combines fiber optic units in wires using a traditional phase structure. The distribution network system avoids conflicts with the outside world in terms of frequency resources, routing coordination, electromagnetic compatibility, etc., making it have dual functions of transmission and communication.
Although the structure of OPPC cable is similar to OPGW cable, there are significant differences in design.
Firstly, due to the role of phase lines, considering the impact of long-term operating temperature on the transmission performance and lifespan of optical fibers, OPPC optical cables can carry electricity for a long time;
Secondly, the mechanical and electrical performance of OPPC optical cables should be consistent with adjacent conductors, such as DC resistance or impedance similar to adjacent wires, to ensure that the remote voltage changes maintain three-phase balance;
Finally, OPPC cables are installed in high-voltage systems, and their installation hardware and accessories (such as tension wire clamps, suspension wire clamps, and terminal junction boxes) require insulation. The wire clamps can use corresponding insulated tension wire strings or insulated suspension strings. Optoelectronic insulation/separation and connection require special techniques and high construction requirements.
What is the difference between OPGW and fiber optic cable?
OPGW cable is one type of overhead fiber optic cable with grounding wire, specially for high-voltage transmission line.
How to install OPGW cable?
Please check article “How to choose OPGW cable?”, you will find answer.
