Structure and Application of OPGW Optical Cable

OPGW cable, Optical Fiber Composite Overhead Ground Wire (also known as fiber composite overhead ground wire).

The optical fiber is placed 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.

Because the optical fiber has the characteristics of anti-electromagnetic interference and light weight, it can be installed on the top of the transmission line tower without considering the optimal hanging position and electromagnetic corrosion. Therefore, OPGW has significant features such as high reliability, superior mechanical properties, and low cost. This technique is especially suitable and economical for new installations or replacement of existing ground wires.

Optical fiber uses the difference in the refractive index of the core and cladding materials to transmit light energy in the optical fiber, which has become a major revolution in the history of communications. Optical fiber cables are light in weight and small in size, and have been used by power systems to transmit dispatching telephones, telecontrol signals, relay protection, TV images and other information between the substation and the central height station.

In order to improve the stability and reliability of fiber optic cables, a structure in which the fiber optic cable is combined with the phase conductor of the transmission line, the overhead ground wire and the power cable has been developed abroad. Because the OPGW optical cable is wrapped with metal wires, the optical cable is more reliable, stable and firm. Because the overhead ground wire and the optical cable are combined into one, compared with the use of other optical cables, it not only shortens the construction period but also saves the construction cost. In addition, if the OPGW made of aluminum clad steel wire or aluminum alloy wire is used, it is equivalent to erecting a good conductor overhead ground wire, which can reduce the potential supply current of the transmission line, reduce the power frequency overvoltage, and improve the power line to the communication line. It has many benefits such as interference and dangerous effects.

Common OPGW structure

There are three main categories: aluminum tube type, aluminum frame type and (stainless) steel tube type.

Application of OPGW Optical Cable

OPGW optical cable is mainly used on 500KV, 220KV, 110KV voltage level lines, and is mostly used on new lines due to line power failure, safety and other factors.

The applicable features of OPGW are:

(1) Lines with high voltage exceeding 110kv have a large span (generally more than 250M);

(2) It is easy to maintain, easy to solve the problem of line crossing, and its mechanical characteristics can meet the large crossing of the line;

(3) The outer layer of OPGW is metal armor, which has no effect on high-voltage electrical corrosion and degradation;

(4) OPGW must be powered off during construction, and the power outage loss is relatively large, so OPGW should be used in new high-voltage lines above 110kv;

(5) In the performance indicators of OPGW, the larger the short-circuit current, the more armored conductors are required, and the tensile strength is correspondingly reduced. However, under the condition of a certain tensile strength, to increase the short-circuit current capacity, only increase The metal cross-sectional area increases, resulting in an increase in the cable diameter and cable weight, which poses a safety issue to the strength of the line tower.

Features of OPGW cable

The armor layer of the optical cable has good mechanical strength characteristics. Therefore, the optical fiber can be best protected from abrasion, tensile stress, and lateral pressure, which fundamentally ensures that the optical fiber is not damaged by external forces. The armored layer of the optical cable has good anti-lightning discharge performance and short-circuit current overload capacity, so the optical fiber can still operate normally in the case of lightning and short-circuit current overload. The OPGW optical cable can be directly installed on the grounding point of the power tower of any span as an overhead ground wire.

The specially designed OPGW optical cable can directly replace the overhead ground wire of the original high-voltage line without replacing the original tower head; the optical cable communication system is constructed in synchronization with the high-voltage line, which can save the construction cost of the optical cable and reduce the cost of the communication project; the cable diameter is small and the weight is light , will not bring a large additional load to the tower; operating temperature -40 ~ +70 ℃.