JPH07199011A - Optical fiber composite overhead earth wire - Google Patents

Abstract

PURPOSE:To obtain an optical fiber composite overhead earth wire which has excellent corrosion resistance and is so considered as to nearly equalize Ge stress bearing of respective strands by subjecting the outer peripheries of stainless steel hollow pipes to aluminum coating or insulator coating. CONSTITUTION:The stainless steel hollow pipes 8 subjected to the coating 10 of aluminum or insulator and aluminum coated wires 9 are mixedly twisted and optical fibers 7 are housed in the coated stainless steel hollow pipes 8. As a result, the aluminum coated wires 9 and the stainless steel hollow pipes 8 are nearly equalized in stress elongation, by which the stress bearing at the time of loading is made equal. Further, the stainless steel hollow pipes 8 subjected to the aluminum coating or insulator coating 10 are disposed on the outermost layer, by which the taking of the surplus lengths of the optical fibers is facilitated and the reliability on elongation is enhanced. This overhead earth wire is spirally housed in a stress relieving material 11, such as jelly, to impart a stress relieving effect for the elongation in the straight direction of the overhead earth wire and to increase the crushing resistance in the stainless steel hollow pipes 8.

Description

Detailed Description of the Invention

[0001]

OBJECT OF THE INVENTION The present invention relates to an overhead ground wire, and more particularly to an optical fiber composite overhead ground wire.

[0002]

2. Description of the Related Art A conventional optical fiber composite overhead ground wire is shown in FIG.
As shown in FIG. 3, the core wire 3 which is inside the core wire 3 and mainly shares the tension, the outer layer wire 4 which is outside the core wire 4 and mainly satisfies the electrical characteristics required for the overhead ground wire, and the core wire 3 Replace a part of this with a hollow, high-quality thin steel pipe 2,
It has a structure in which the optical fiber 1 is housed therein. In general, an aluminum-covered steel wire is used for the core wire 3, an aluminum or aluminum alloy wire is used for the outer layer wire, and a stainless steel tube is used for the hollow tube 2. As another conventional example, as shown in FIG. 6, there is a structure in which an aluminum hollow tube 6 is arranged at or near the center of a plurality of galvanized steel wires 5, and an optical fiber 1 is inserted into this tube. .

[0003]

[Problems of the prior art] In the prior art shown in FIG. 5, when the overhead ground wire is clamped, the outer layer wire 4 made of an aluminum element wire is more easily stretched than the core wire 3 made of an aluminum covered steel wire. As a result, there is a high probability that stress will concentrate on the aluminum wires and lead to breakage of the aluminum wires. Further, there is a problem that aluminum is corroded at a place where the stainless hollow tube 2 and the aluminum outer layer wire 4 or the core wire 3 made of aluminum-covered steel wire contact each other. Regarding this point, the present inventors have proposed a corrosion acceleration test (salt spray test) by winding a stainless hollow tube and a galvanized stainless hollow tube of the same diameter around the outer circumference of an aluminum-coated steel wire having an outer diameter of 2.5 mm. ) Was carried out,
After one week, the stainless steel hollow tube and the galvanized stainless steel hollow tube did not show any abnormality, but the aluminum-coated steel wire corroded aluminum and exposed the inner steel wire. I have confirmed that. On the other hand, in the conventional technique shown in FIG. 6, the aluminum hollow tube 6 is corroded and damaged by the galvanized steel wire 5, and the optical fiber therein is damaged by intrusion of water or the like. Moreover, since aluminum hollow tubes are weak against lateral pressure, they are likely to be crushed during mixed twisting or during overhead wire construction. Further, if a metal tube containing an optical fiber is arranged near the center, there is a problem in that it is difficult to secure a surplus length of the optical fiber that can counter the elongation of the entire overhead ground wire. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned drawbacks of the prior art, and to provide an optical fiber composite overhead ground wire which is excellent in corrosion resistance and is designed so that the stress distribution of each element wire is substantially equal.

[0004]

According to the present invention, the outer circumference of a stainless steel hollow tube is coated with aluminum or an insulator to prevent corrosion due to contact with an aluminum-covered steel wire, and the entire wire is made of aluminum. By covering the steel wire, the stress distribution is equalized. Further, by using a stainless steel hollow tube coated with aluminum as a part of the outer layer wire, it becomes easy to take a surplus length of the optical fiber which is sufficient to counter the elongation of the overhead ground wire. Hereinafter, further details will be described with reference to examples.

[0005]

FIG. 1 shows a first embodiment of an optical fiber composite overhead ground wire according to the present invention. A stainless hollow tube 8 coated with aluminum or an insulating material 10 and an aluminum-coated steel wire 9 are mixed and twisted to form the coated stainless hollow tube 8 described above.
An optical fiber 7 is housed inside. Polyethylene, plastic, silicon rubber or the like is used as the insulator coating material. By using an aluminum-covered steel wire having a large aluminum thickness, it is possible to maintain the electrical characteristics shared by the conventional aluminum outer layer wire shown in FIG. In consideration of the crushing strength to the stainless hollow tube 8, the outer diameter of the stainless hollow tube 8 is a small diameter of about 1.5 to 3.5 mm, and the gap between the optical fiber 7 housed therein and the inner wall of the tube is set. Considering this, the wall thickness is preferably about 0.1 to 0.2 mm. The aluminum covered steel wire has a diameter of 1.5 to 3.5 mm. As a result, the stress elongations of the aluminum-covered steel wire 9 and the stainless hollow tube 8 become substantially equal, and the stress distribution during loading can be equalized.
Since the hollow stainless steel tube 8 has a small diameter, a compression load test with a 50 mm plate, which is a guideline assuming the compression force that the optical fiber overhead ground wire receives during construction or after the overhead wire, has a compression yield strength of 500 kg or more. I was able to get In the conventional general structure in which a single optical fiber-containing metal tube is placed in the center and an aluminum-covered steel wire is stranded around it, only a maximum of 24 optical fibers can be inserted in a 6 mmφ tube. However, if an aluminum-covered steel wire is placed around this, the outer diameter of the overhead ground wire is required to be φ12.2 mm. However, in the present invention, for example, 12 optical fibers can be put in a 2.5 mmφ stainless steel hollow tube, so as shown in FIG. 2, 13 aluminum covered steel wires 9 and an optical fiber 7 are placed in an aluminum tube. Alternatively, if six stainless hollow tubes 8 coated with an insulator 10 are mixed-twisted, the outer diameter φ12.
It is possible to accommodate 72 optical fibers in a 5 mm overhead ground wire, and it is also possible to cope with an ultra-multifiber. Further, as shown in FIG. 3, by disposing the stainless steel hollow tube 8 coated with aluminum or the insulator 10 in the outermost layer, the extra length of the optical fiber is easily taken, and the reliability of elongation is increased. Further, the optical fiber in the stainless hollow tube 8 needs to be considered so that the elongation of the overhead ground wire is not applied as it is, and is housed in the stress relaxation material 11 such as jerry in a spiral shape, and It is desirable to have a stress relaxation effect on elongation. Further, by filling the entire tube with this jelly, there is also an effect of increasing the crushing resistance inside the stainless steel hollow tube 8. Silicone jelly is used for jelly. In order to further reduce the lateral pressure on the stainless hollow tube, the coated stainless hollow tube 8 according to the present invention may be placed in a spacer 12 of high hardness, as shown in FIG.

[0006]

The optical fiber composite overhead ground wire of the present invention has the following effects. 1. By using a stainless hollow tube whose outer periphery is covered with aluminum or an insulator, it is possible to prevent corrosion due to contact with the aluminum-covered steel wire. 2. Since all the wires are made of aluminum-covered steel wire, the stress distribution can be made uniform and the pressure resistance can be improved. 3. By using a stainless steel hollow tube coated with aluminum or an insulator as a part of the outer layer wire, it becomes easy to obtain a fiber surplus length that is sufficient to resist the elongation of the overhead ground wire. 4. By filling a stress relaxation material such as jelly in a stainless steel hollow tube coated with aluminum or an insulator, it is possible to increase the crushing resistance of the stainless steel hollow tube while relaxing the stress on the optical fiber. 5. A plurality of coated stainless steel hollow tubes for accommodating optical fibers according to the present invention can be arranged, so that a super multi-core optical fiber composite overhead ground wire can be easily realized. 6. By using a plurality of coated stainless hollow tubes according to the present invention, compared to an optical fiber composite overhead ground wire in which all the fibers are housed in a single metal tube, the branching of the optical fiber system is improved. It will be easy. That is, by accommodating the optical fibers required by each optical fiber system in each of the stainless steel hollow tubes and branching them, it is easy to systemize without touching the optical fibers in other stainless steel hollow tubes. You can

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a second embodiment of the optical fiber composite overhead ground wire of the present invention.

FIG. 3 is a cross-sectional view showing a third embodiment of the optical fiber composite overhead ground wire of the present invention.

FIG. 4 is a cross-sectional view showing a fourth embodiment of the optical fiber composite overhead ground wire of the present invention.

FIG. 5 is a cross-sectional view of an example of a conventional optical fiber composite overhead ground wire.

FIG. 6 is a cross-sectional view of another example of a conventional optical fiber composite overhead ground wire.

[Explanation of symbols]

 1 Optical Fiber 2 Stainless Steel Hollow Tube 3 Core Wire 4 Outer Layer Wire 5 Galvanized Steel Wire 6 Aluminum Hollow Tube 7 Optical Fiber 8 Stainless Steel Hollow Tube 9 Aluminum Covered Steel Wire 10 Coating 11 Jerry 12 Spacer

Claims (3)

[Claims] 1. An optical fiber is housed in a stainless hollow tube whose outer peripheral surface is coated with aluminum or an insulator.
An optical fiber composite overhead ground wire obtained by mixing and twisting a plurality of the coated stainless hollow tubes and a plurality of aluminum-covered steel wires. 2. The optical fiber according to claim 1, wherein jelly as a stress relaxation material is filled in a stainless steel hollow tube whose outer peripheral surface is coated with aluminum or an insulator, and an optical fiber is housed therein. Fiber composite overhead ground wire. 3. The optical fiber composite overhead ground wire according to claim 1, wherein a stainless hollow tube having an outer peripheral surface coated with aluminum or an insulator is arranged in a part of the outer layer wire.