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 Fiber Optic Cable in Electricity
One of common practice of fiber optic cable is to bundle many fiber optic strands within long-distance power transmission cable. This exploits power transmission rights of way effectively, ensures a power company can own and control the fiber required to monitor its own devices and lines, is effectively immune to tampering, and simplifies the deployment of smart grid technology.
An optical ground wire (also known as an OPGW or, in the IEEE standard, an optical fiber composite overhead ground wire) is a type of cable that is used in the construction of electric power transmission and distribution lines. Such cable combines the functions of grounding and communications. An OPGW cable contains a tubular structure with one or more optical fibers in it, surrounded by layers of steel and aluminum wire. The OPGW cable is run between the tops of high-voltage electricity pylons. The conductive part of the cable serves to bond adjacent towers to earth ground, and shields the high-voltage conductors from lightning strikes. The optical fibers within the cable can be used for high-speed transmission of data, either for the electrical utility's own purposes of protection and control of the transmission line, for the utility's own voice and data communication, or may be leased or sold to third parties to serve as a high-speed fiber interconnection between cities.
The optical fiber itself is an insulator and protects against power transmission line and lightning induction, external noise and cross-talk. Typically OPGW cables contain single-mode optical fibers with low transmission loss, allowing long distance transmission at high speeds. The outer appearance of OPGW is similar to ACSR cable usually used for shield wires.
Several different styles of OPGW are made. In one type, between 8 and 48 glass optical fibers are placed in a plastic tube. The tube is inserted into a stainless steel, aluminum, or aluminum-coated steel tube, with some slack length of fiber allowed to prevent strain on the glass fibers. The buffer tubes are filled with grease to protect the fiber unit from water and to protect the steel tube from corrosion, the interstices of the cable are filled with grease. The tube is stranded into the cable with aluminum, aluminum alloy or steel strands, similar to an ACSR cable. The steel strands provide strength, and the aluminum strands provide electrical conductivity. For very large fiber counts, up to 144 fibers in one cable, multiple tubes are used.
In other types, an aluminum rod has several spiral grooves around the outside, in which fibers in buffer tubes are laid. The fiber unit is covered with a plastic or steel tape, and the whole surrounded with aluminum and steel strands.

Individual fibers may be in "loose buffer" tubes, where the inside diameter of the tube is greater than the fiber outside diameter, or may be "tight buffered" where the plastic buffer is coated directly on to the glass. Fibers for OPGW are single-mode type.
Optical fibers are used by utilities as an alternative to private point to point microwave systems, power line carrier or communication circuits on metallic cables.
OPGW as a communication medium has some advantages over buried optical fiber cable. Installation cost per km is lower than a buried cable. Effectively, the optical circuits are protected from accidental contact by the high voltage cables below (and by the elevation of the OPGW from ground). A communications circuit carried by an overhead OPGW cable is unlikely to be damaged by excavation work, road repairs or installation of buried pipelines. Since the overall dimensions and weight of an OPGW is similar to the regular grounding wire, the towers supporting the line do not experience extra loading due to cable weight, wind and ice loads.
An alternative to OPGW is use of the power cables to support a separately-installed fiber bundle. Other alternatives include fiber-bearing composite power conductors (OPCC), or using transmission towers to support a separate All-Dielectric Self-Supporting fiber cable with no conductive elements
A utility may install many more fibers than it needs for its internal communications both to allow for future needs and also to lease or sell to telecommunications companies. Rental fees for these "dark fibers" (spares) can provide a valuable source of revenue for the electrical utility. However, when rights-of-way for a transmission line have been expropriated from landowners, occasionally utilities have been restricted from such leasing agreements on the basis that the original right of way was only granted for electric power transmission.
Lower-voltage distribution lines may also carry OPGW wires for bonding and communications; however, utilities may also install all-dielectric self-supporting (ADSS) cables on distribution pole lines. These cables are somewhat similar to those used for telephone and cable television distribution.
While OPGW is easily installed in new construction, electrical utilities find the increased capacity of fiber to be so useful that techniques have been worked out for replacement of ground wires with OPGW on energized lines. LIve-line working techniques are used to re-strand the towers with OPGW replacing the all-metal type of overhead shield wires.

ADSS (all-dielectric self-supporting) cable is a type of optical fiber cable that contains no conductive metal elements. It is used by electrical utility companies as a communications medium, installed along existing overhead transmission lines and often sharing the same support structures as the electrical conductors.
ADSS is an alternative to OPGW with lower installation cost. The cables are designed to be strong enough to allow lengths of up to 700 meters or longer span to be installed between support towers. ADSS cable is designed to be light weight and small in diameter to reduce the load on tower structures due to cable weight, wind, and ice.
ADSS cable is designed to support the internal glass optical fibers with no strain, to maintain low optical loss throughout the life of the cable. The cable is jacketed to prevent moisture from degrading the fibers. The jacket also protects the polymer strength elements from the effect of solar ultraviolet light.
Using single-mode fibers and light wavelengths of either 1310 or 1530 nanometres, circuits up to 100 km long are possible without repeaters. A single cable can carry as many as 144 fibers.

Baifu China has the reputation for creation of innovative designs that produce the most dependable cables for deployment in the electricity circuit applications.

Unique designs and manufacturing processes for ADSS and OPGW provide the best mechanical and environmental protection for the optical fibers in electricity circuit. Our products include many that are particularly suited for tough, demanding industrial applications, some of which are featured in this section of our catalog. For more fiber optic cable choices, also see the fiber optic cables section of the catalog.