JPS61281408A - Optical fiber composite overhead ground wire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Subject of invention] The present invention relates to an optical fiber composite overhead ground wire.

[Prior art 1 and problems] Traditionally, wired systems and control lines have been used for communication and control lines in the power field.
A microwave method is used.

However, in the wired system, it is extremely troublesome to separate communication and control lines, and there is also the disadvantage that it is affected by noise from power lines and lightning strikes.

In the microwave method, since it is wireless, the transmission line is not interrupted, but the amount of information required has increased in recent years, making it extremely difficult to allocate microwaves. The effect of noise was unavoidable.

For this reason, a composite electric cable has recently been proposed in which a power cable and an optical fiber are integrated. (For example, Japanese Utility Model Application No. 50-62542) With this composite electric cable, there is no need to separate the communication and control lines. ■
Unlike the microwave method, there are no allocation problems. ■
Since it uses optical fiber, electromagnetic induction interference is not a problem and the signal is highly reliable. It has the advantages of
It is effective as a communication line accompanying a power transmission line that has a large amount of information and is highly reliable.

However, apart from laying underground power between substations in urban areas, it is not very practical to install such composite power cables throughout the country. In other words, since the electrical cable and optical fiber are coated with an insulating protective coating and integrated into one, the price per unit length is high, which makes it uneconomical, and if it is installed overhead, it may be damaged by lightning strikes, etc. easy to use and unreliable.

Also, if you keep in mind that it will be installed in rural mountainous areas,
It is conceivable to twist or attach an overhead power transmission line made of bare metal wire and an optical fiber together. (Swiss patent No. 567730 shows a similar structure.) However, the thermal expansion coefficient and Young's modulus of bare metal wire and optical fiber are significantly different, and optical fiber is extremely fragile. If an optical fiber is installed with such a structure, the optical fiber will easily be damaged during normal, calm use.

If the cable is installed overhead, it is expected that it will be affected by wind, snow, lightning, etc., so it is unlikely that this type of structure will provide practical reliability.

[Prior Art Part 2 and Problems] Next, as shown in FIG. 3, the optical fiber 3 is housed in one or more metal tubes 2, and the metal tube 2 is connected to a power transmission line made of bare metal wire. 1 and a hanging fixture 5 may be used to attach and integrate them.

Even with such a configuration, a communication line can be secured at the same time as the power transmission line. ■There are no allocation problems like with the microwave method. ■Since it uses optical fiber, electromagnetic induction interference is not a problem and it is highly reliable. In addition to the same effects as in prior art No. 1, (1) Since the bare metal wire is used as the power transmission line, it is more economical than the conventional composite type installed cable in which the power cable is used as the transmission rIi line. ■Since the optical fiber is housed in a metal tube, it is more reliable than conventional technology 1, which is simply integrated. This has this effect.

In other words, even if the power transmission line expands or contracts, this effect will affect the metal tube, but it will not directly affect the optical fiber housed inside the metal tube, and the optical fiber can avoid stress by sliding inside the metal tube. .

However, such technology still has the following major problems.

(a) Handling is complicated because it is integrated with a bare power transmission line carrying m voltage. In other words, although the optical fiber itself is an insulator, there is a risk that the lead-out section may become contaminated and cause creeping discharge, etc., and it is also necessary to stop power transmission for maintenance of the optical fiber section, so various measures are required. becomes.

(b) Since power transmission lines require a certain amount of current capacity, they are mainly made of highly conductive metals such as aluminum, and tensile strength cannot always be prioritized when selecting them, so they tend to have large outer diameters and large sag.

As a result, they vibrate greatly under the influence of wind pressure, which can easily cause damage to the optical fiber.

(C) Since it has a hanging device and has a special external shape, the installation work is extremely troublesome.

(d) Since the metal tube housing the optical fiber is exposed on the surface, it is susceptible to external influences such as lightning strikes and bird strikes, and the tube housing the optical fiber is easily damaged.

[Techniques prior to the present invention] Under these circumstances, the present inventors invented the following configuration.

In other words, "a space partitioned by a hollow pipe is formed at or near the center of an overhead ground wire in which multiple conductive bare metal wires are twisted together, and within the space there is a single or "An optical fiber composite overhead ground wire characterized by accommodating a plurality of optical fibers."

Overhead ground wires are not power transmission lines themselves, but are installed alongside power transmission lines on towers.

Such an optical fiber composite overhead ground wire provides the following remarkable effects in addition to the effects achieved in the prior art described above.

(a) Since the optical fiber is built into the overhead ground wire, which does not carry voltage during normal operation, there is no need to take special measures to withstand voltage at the optical fiber lead-out section, and it is necessary to stop power transmission for maintenance of the optical fiber section. It is easy to handle.

(b) Overhead ground wires have smaller current capacity requirements than power transmission lines, so they can be made smaller in diameter and have less sag. As a result, the influence of wind pressure is small and the amplitude is small, making it difficult for optical fibers to be damaged.

(C) Since the hollow pipe is placed at or near the center of the twisted bare metal wire, there is no need for a hanging device to integrate the overhead ground wire and the hollow pipe, and the external shape is also small. Since it can be made into a substantially circular shape, installation work is easy.

(d) Since the hollow tube containing the optical fiber is placed at or near the center of the overhead ground wire, it is less susceptible to external influences and the reliability of the optical fiber communication line is high. In particular, since the optical fiber is housed in a hollow tube, it is possible to incorporate it with any margin to the bare metal wire, and when the optical fiber is twisted or attached directly to the bare metal wire The optical fiber is not easily damaged and is highly reliable.

Although the above-mentioned structure which produces such a significant effect is extremely excellent, there is one problem that has posed a problem in industrial production.

It is a method of drawing an optical fiber into a hollow tube.

At first, we considered using wire to pull in the optical fiber, but when it becomes long, the friction between the surface of the optical fiber and the hollow tube makes it difficult to pull in easily, and it is much weaker than electric wire, so we decided not to use optical fiber instead. This was a problem because it could get damaged.

Therefore, we investigated the coating material for the optical fiber and tried to select a material that is neither too hard nor too soft and has low S friction resistance, but this did not provide a definitive solution.

LObject and Summary of the Present Invention] In view of the above circumstances, the present invention achieves all of the above-mentioned effects,
Moreover, the purpose is to provide an optical fiber composite overhead ground wire that can solve these problems. A space partitioned by a hollow tube is formed at or near the center of the line, and one or more optical fibers are accommodated in the space, and the hollow tube is assembled after accommodating the optical fiber. An optical fiber composite overhead ground wire characterized in that the wire is welded.
It is in.

The hollow tube housing the optical fiber here is an aluminum tube,
Although galvanized steel pipes and the like are practical, pipes made of other materials may also be used.

Further, as the bare metal wire, a conductive metal wire such as a galvanized steel wire, an aluminum coated wire, or an aluminum wire can be practically used.

One or more optical fibers are housed in parallel or twisted together in a hollow tube, and inclusions other than the optical fiber (including solid, liquid, and gaseous ones) are also housed in the hollow tube. You can leave it there.

[Example] The configuration of the present invention will be specifically described with reference to explanatory diagrams showing one example.

In Figure 1, 1 is a bare metal wire such as a galvanized steel wire, an aluminum coated wire, or an aluminum wire, and 2 is a hollow tube such as an aluminum pipe or a galvanized steel pipe placed at or near the center of the bare metal wire. and an optical fiber is inserted.

Figure 2 shows this hollow tube 2 in detail.
Insert the optical fiber 3 into the open tube 21 and weld the seam 4.
This is what I did.

As can be seen in the drawing, the open tube is not a complete tube, but an incomplete tube with one longitudinal side open. Although a tube having such a shape may be manufactured by extrusion, it is generally known that it is more common to form a tape-shaped body by rolling it, and the present invention also uses a conventionally known method. It is sufficient to adopt it and form the tube.

In any case, an optical fiber is housed in an incomplete tube shaped like a rolled tape, and then the seam is welded to make the tube a complete watertight tube.

A tube 2 containing one or more optical fibers is placed at or near the center, and a plurality of conductive bare metal wires 1 are twisted together as shown in FIG. The combined outermost layer consists entirely of bare metal filaments.

[Effects of the invention] The optical fiber composite overhead ground wire of the present invention can achieve all the effects (aHb) (cHd) achieved in the previous stage technology, and also There is no need to pull a fragile optical fiber from one end to the other end, and it is possible to insert an optical fiber from the opening of an incomplete pipe.
Since it is possible to wrap the optical fiber in a tape-like body or to accommodate it in any manner, it is extremely easy to industrially produce a long optical fiber composite overhead ground wire, and welding is performed afterwards. Watertightness is also not impaired.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and FIG.
FIG. 3 is an explanatory diagram showing a partial example of the figure, and FIG. 3 is an explanatory diagram showing a conventional technique. 1: Bare metal wire, 2: Tube, 3: Optical fiber, 4: Welding. M 1 mouth

Claims (1)

[Claims] (1) A space partitioned by a hollow pipe is formed at or near the center of an overhead ground wire in which multiple conductive bare metal wires are twisted together, and within the space there is a single or 1. An optical fiber composite overhead ground wire, characterized in that a plurality of optical fibers are housed in the hollow tube, and the joints of the hollow tube are welded after housing the optical fibers.