JPH07220537A - Composite optical fiber overhead ground wire - Google Patents

Abstract

PURPOSE:To provide a composite optical fiber overhead ground wire whose protective pipe housing an optical fiber is prevented from corroding and does not melt even if lighting directly strickes the wire and with which stable information transmission system based on the optical fiber can be established. CONSTITUTION:A corrosion-proof layer 10 made of a metal or an alloy, e.g. zinc or a zinc alloy, is formed on a protective pipe 6 made of aluminum or an aluminum alloy and in which an optical fiber cable 7 is housed, wherein the metal or the alloy for the layer 10 has lower melting point than the protective pipe 6. In addition, a plurality of conductive wires such as steel wires 11 coated with aluminum, are standard together.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber composite overhead ground wire in which protection pipes for accommodating optical fibers are prevented from being corroded and from being damaged by lightning.

[0002]

2. Description of the Related Art Optical fiber composite overhead ground wire (OPGW)
Is an optical fiber combined with an overhead ground wire to have a communication transmission function. For example, as shown in FIG. 3, each concave groove of the spacer 1 having a plurality of concave grooves 1a spirally provided on the outer circumference. 1
Insert the optical fiber cable 2 into a, store it in a protection pipe 3 made of aluminum or aluminum alloy, and twist a plurality of conductive wires 4 such as aluminum-covered steel wire in a concentric pattern on the outer circumference of the protection pipe 3. It is known that they are combined. In such an OPGW, the anticorrosion layer 5 is provided on the protective pipe 3 in order to prevent rainwater containing a corrosive substance from entering through the gap between the conductive wires 4 and corroding the protective pipe 3. It is provided (see Japanese Utility Model Publication No. 62-144015).

[0003]

By the way, for the purpose of using the OPGW, it is necessary to take sufficient measures against lightning on the optical fiber cable 1 and the protection pipe 4 accommodating the optical fiber cable 1. That is, it is necessary to prevent the protection pipe 4 from being damaged and the communication transmission function of the optical fiber cable 1 from being damaged even if a lightning strike is received.

However, the conventional OP as described above
Although the GW has an anticorrosion effect, it does not take any measures against lightning strikes. Therefore, when a lightning strike hits directly, the protection pipe 4 made of aluminum or an aluminum alloy is exposed to a sudden temperature rise due to a lightning current. Might melt and cause breakage or deterioration of the characteristics of the optical fiber cable 1 housed inside.

The present invention has been made in order to solve such a conventional problem. The optical fiber has an anticorrosion effect and does not melt the protective pipe for accommodating the optical fiber even if the lightning strikes directly. The purpose is to provide a composite overhead ground wire.

[0006]

The present invention relates to an optical fiber composite overhead ground wire formed by twisting a plurality of conductive wires around the outer circumference of a protective pipe for housing an optical fiber, and twisting the protective pipe and the conductive wires. It is characterized in that an anticorrosion layer made of a metal or an alloy having a melting point lower than that of the protective pipe is provided between the layer and the layer. Particularly, in this case, it is desirable that the protective pipe is made of aluminum or an aluminum alloy and the anticorrosion layer is made of zinc or a zinc alloy.

[0007]

In the optical fiber composite overhead ground wire of the present invention,
The anticorrosion layer provided on the protective pipe can prevent corrosion of the protective pipe. Further, when a direct lightning strike is received, the lightning current first selectively melts the anticorrosion layer made of a metal or alloy having a low melting point on the protective pipe. For this reason, lightning energy is consumed by its melting before being transmitted to the protection pipe, and the influence of lightning energy on the protection pipe is greatly suppressed. Prevents serious accidents such as disconnection of the optical fiber stored in.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an optical fiber composite overhead ground wire according to an embodiment of the present invention.

In FIG. 1, reference numeral 6 denotes a protective pipe made of aluminum or aluminum alloy. Inside the protective pipe 6, a plurality of optical fiber cables 7 are inserted into the concave grooves 1 of a spacer 9 made of aluminum or an aluminum alloy having a plurality of concave grooves 8 spirally provided on the outer periphery and stored. Has been done. As shown in FIG. 2, for example, the optical fiber cable 7 has a reinforcing core 7a made of FRP and the like, and a plurality of optical fiber strands 7c twisted around the reinforcing core 7a via a buffer layer 7b made of silicone resin or the like. A heat-resistant coating 7d made of a heat-resistant tape or the like is provided on the outside thereof.

On the other hand, on the protective pipe 6, the anticorrosion layer 1 made of a metal or an alloy having a melting point lower than that of the protective pipe 6.
0 is provided, and a plurality of aluminum-covered steel wires 11 having a circular cross section in which the surface of the steel wire 11a is covered with aluminum 11b are twisted on the anticorrosion layer 10.

The low melting point metal or alloy forming the anticorrosion layer 10 is appropriately determined depending on the material of the protective pipe 6. For example, when the protective pipe 6 is made of aluminum or aluminum alloy having a melting point of about 650 ° C., the melting point is 420 ° C. The use of front and rear zinc or zinc based alloys is preferred. This is because not only the lightning resistance effect according to the present invention is excellent, but also zinc or a zinc-based alloy has an excellent corrosion prevention effect on aluminum or an aluminum alloy and is easily available. The thickness of the anticorrosion layer 10 is preferably about 0.5 to 0.6 mm.

In the optical fiber composite overhead ground wire constructed as described above, when there is a direct lightning strike, the lightning current first selectively causes the anticorrosion layer 10 made of a metal or alloy having a low melting point on the protective pipe 6. It is melted and most of the lightning energy is consumed by this melting. Therefore, the influence of the lightning energy on the protection pipe 6, the spacer 9, and the optical fiber cable 7 is suppressed, and the protection pipe 6 and the spacer 9 are melted, and the optical fiber cable 7 accompanying it is melted.
It is possible to prevent disconnection and deterioration of characteristics.

Further, the anticorrosion layer 10 on the protective pipe 6 prevents the protective pipe 6 from being corroded. In particular, when the protective pipe 6 is made of aluminum or an aluminum alloy and the anticorrosion layer 10 is made of zinc or a zinc-based alloy, as described above, the zinc or zinc-based alloy is corroded by aluminum or an aluminum alloy, for example, Since it has an excellent effect of preventing corrosion due to rainwater or the like, it is possible to effectively prevent the damage to the protective pipe 6 and the disconnection accident of the optical fiber cable 7 due to such corrosion.

In order to manufacture the above-mentioned optical fiber composite overhead wire, for example, the surface of the tape for the protective pipe is coated with a low melting point metal or alloy in advance, and this is put into a spacer into which the optical fiber cable 7 is inserted. 9 While forming a pipe shape with the low melting point metal or alloy surface on the outer periphery, weld the joints and coat them, and once wind up on a drum,
The aluminum-covered steel wire 11 may be twisted around the wound optical fiber cable built-in pipe while sending it from the drum. Alternatively, the surface of the protective pipe tape is not coated with a low melting point metal or alloy, but only the protective pipe tape is coated on the outer periphery of the spacer 9 into which the optical fiber cable 7 is inserted to obtain a pipe with a built-in optical fiber cable. While feeding this from the drum, a tape made of a low melting point metal or alloy may be vertically attached or wound around the drum, and the aluminum covered steel wire 11 may be twisted on the tape.

The embodiment described above is an example in which the optical fiber cable 7 is applied to an optical fiber composite overhead ground wire which is inserted into a plurality of concave grooves 8 provided on the outer periphery of the spacer 9 and is housed in the protective pipe 6. However, the present invention is not limited to such an embodiment, and although illustration is omitted, the optical fiber cable 7 is simply accommodated in the protective pipe 6, and the optical fiber cable 9 is interposed and the protective pipe 6 is provided. A plurality of optical fiber cables 9 to be housed in
It can be applied to any type of optical fiber composite overhead ground wire as long as the optical fiber is housed in the protective pipe 6, such as one housing a heat resistant coating on its outer periphery.

The above embodiment is an example in which an aluminum-covered steel wire is used as the conductive wire of the present invention. However, an aluminum ground wire, an aluminum alloy wire, a galvanized steel wire, or the like is a conventional conductive wire for overhead ground wire. Anything used as can be used.

[0018]

As described above, in the optical fiber composite overhead ground wire of the present invention, the anticorrosion layer made of a metal or alloy having a lower melting point than the protective pipe is provided on the protective pipe for housing the optical fiber. Since it has a structure, the protection pipe has an anticorrosion effect. Also, even if you get a lightning strike,
The protection pipe is less likely to melt, and the breakage of the optical fiber contained in the protection pipe and the deterioration of the characteristics thereof are suppressed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an optical fiber composite overhead ground wire according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a structural example of an optical fiber cable used in the embodiment shown in FIG.

FIG. 3 is a cross-sectional view showing an example of a conventional optical fiber composite overhead ground wire.

[Explanation of symbols]

 6 ………… Protection pipe 7 ………… Optical fiber cable 10 ………… Corrosion protection layer 11 ………… Aluminum covered steel wire

Claims (2)

[Claims] 1. An optical fiber composite overhead ground wire formed by twisting a plurality of conductive wires around an outer circumference of a protective pipe for accommodating an optical fiber, wherein a protective pipe is provided between the protective pipe and a twisted layer of the conductive wires. An optical fiber composite overhead ground wire, comprising an anticorrosion layer made of a metal or an alloy having a lower melting point. 2. The optical fiber composite aerial ground according to claim 1, wherein the protective pipe is made of aluminum or an aluminum alloy, and the anticorrosion layer is made of zinc or a zinc alloy. line.