JP2002075077A - Fiber-optic composite aerial cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the clearance corrosion which occurs between a metal pipe housing a fiber-optic unit of an fiber-optic composite aerial cable and a twisted wire part made of twisted metal strands, so as to prevent degradation and deterioration of the fiber-optic unit in a metal pipe. SOLUTION: A clearance larger than 0.4 mm is formed between the metal pipe 1 and the twisted wire part 3 by winding wire material 5 around or attaching lengthwise wiry material 5 to the circumference surface of the metal pipe 1.

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 wire in which an overhead line such as an overhead power transmission line, an overhead ground wire, an overhead shield wire, etc. is combined with an optical fiber, and relates to corrosion of a metal pipe containing an optical fiber. Is to be prevented.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a conventional optical fiber composite overhead wire of this type, wherein reference numeral 1 denotes a metal pipe. The metal pipe 1 is a long piece made of metal such as aluminum, aluminum alloy, stainless steel, etc., and has various forms of light such as optical fiber cores, optical fiber tape cores, and optical fiber cords inside. The fiber unit 2 is loosely housed with a slight gap. Around the metal pipe 1, a stranded wire portion 3 is provided.

The twisted wire portion 3 is formed by twisting a plurality of metal wires 4, 4... Such as a plurality of aluminum-coated steel wires, aluminum-coated deformed steel wires, aluminum alloy wires, etc. over one or more layers on a metal pipe 1. In this example, an aluminum-coated steel wire is twisted directly above the metal pipe 1, and an aluminum alloy wire is further twisted thereon.
The optical fiber composite overhead wire having such a structure is laid on a power transmission tower or the like, and optical communication can be performed by the optical fiber unit 2 accommodated in the metal pipe 1.

Incidentally, in the optical fiber composite overhead wire having such a structure, the metal pipe 1 and the stranded wire portion 3 are almost in close contact with each other. For this reason, when rainwater or the like containing chlorine such as salt intrudes into a slight gap between the metal pipe 1 and the stranded wire portion 3, crevice corrosion occurs between the metal pipe 1 and the stranded wire portion 3. When the corrosion of the metal pipe 1 progresses, the optical fiber unit 2 inside the metal pipe 1 is deteriorated by hydrogen gas generated by the corrosion, and the transmission loss increases. Further, when the stranded wire portion 3 is corroded, the corrosion product immerses the metal pipe 1 and applies compressive strain to the optical fiber unit 2 to increase transmission loss or damage the metal pipe 1.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent crevice corrosion between a metal pipe and a stranded portion of an optical fiber composite overhead wire, and to prevent deterioration or deterioration of an optical fiber unit in the metal pipe. The purpose is to prevent immersion.

[0006]

This problem can be solved by forming a gap between a metal pipe containing an optical fiber unit of an optical fiber composite overhead wire and a stranded wire portion. The gap is preferably set to 0.4 mm or more, and the gap is formed by wrapping a wire around a metal pipe or attaching it vertically.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
1 and 2 show an example of an optical fiber composite overhead wire according to the present invention. FIG. 1 is a sectional view, and FIG. 2 is an exploded perspective view. The optical fiber composite overhead wire shown in FIGS. 1 and 2 is different from the conventional optical fiber composite overhead wire shown in FIG. 3 in that a gap is formed between the metal pipe 1 and the stranded wire portion 3, The formation of the gap allows the wire 5 to be connected to the metal pipe 1.
In that it is wound in a spiral around the outer periphery of

The wire 5 is a long wire such as a metal wire such as an aluminum wire, an aluminum alloy wire, a stainless steel wire, or a galvanized steel wire, or a plastic wire made of polypropylene, nylon, polyethylene terephthalate, or the like. Its cross-sectional shape has an arbitrary shape such as a round shape, a square shape, and an irregular shape. When the metal pipe 1 is made of aluminum or an aluminum alloy, the wire 5 is preferably made of aluminum or an aluminum alloy. When the metal pipe 1 is made of stainless steel, the wire 5 is made of aluminum. , Aluminum alloy, and stainless steel are preferably used.

The thickness of the wire 5, that is, the diameter corresponding to the diameter of the round wire, the height corresponding to the square wire and the deformed wire when wound around the metal pipe 1 is 0.4 mm or more, preferably 0.5 to 0.5 mm. When the thickness is less than 0.4 mm, crevice corrosion cannot be prevented.

As another example of the present invention, a plurality of the above-mentioned wires 5 may be used, and these may be vertically and linearly attached to the metal pipe 1. The interval between the vertically attached wires 5 is the metal pipe 1
When the diameter is less than 1/8, the effect of preventing crevice corrosion is no longer improved, and conversely, the amount of wire 5 used increases. Further, the contact portion between the metal pipe 1 and the stranded wire portion 3 is partially increased, and there is a possibility that crevice corrosion occurs at that portion.
Further, the gap between the metal pipe 1 and the stranded wire portion 3 is reduced,
The corrosion product generated in the metal wire 4 cannot be accommodated, and the effect cannot be obtained.

Further, as another example of the present invention, a metal pipe 1 in which ribs having a projecting height of 0.4 mm or more, preferably about 0.5 to 3 mm are formed in a spiral shape on the outer peripheral surface, A gap may be formed between the metal pipe 1 and the stranded portion 3 by using a plurality of ribs formed in the longitudinal direction.

In the optical fiber composite overhead wire having such a structure, a gap of 0.4 mm or more is formed between the metal pipe 1 and the stranded wire portion 3 over the entire length thereof. Even if rainwater or the like enters between the stranded wire portion 3 and the stranded wire portion 3, crevice corrosion does not occur, and only normal corrosion occurs in the metal pipe 1 or the stranded wire portion 3. For this reason, the time until the metal pipe 1 is corroded and the optical fiber unit inside the metal pipe 1 is deteriorated can be extended.
Further, even if the stranded wire portion 3 is corroded and a corrosion product is generated, the corroded organism spreads in the gap, so that the metal pipe 1 is not directly crushed, and the internal optical fiber unit 2 is not crushed.
Is not damaged.

As a method of manufacturing such an optical fiber composite overhead wire, a wire 5 is wound around an outer peripheral surface of a metal pipe 1 in which an optical fiber unit 2 is previously housed, and subsequently, metal wires 4, 4. There is a method of twisting. Further, a plurality of wires 5, 5, 5
Are temporarily attached by spot welding or the like, and then the metal strands 4, 4,.

In order to accommodate the optical fiber unit 2 in the metal pipe 1, a long metal tape to be the metal pipe 1 is continuously fed into a pipe forming device, and formed into a pipe while being formed therein. Optical fiber unit 2
And the seam welding of the butt portion of the metal tape is performed.

In the present invention, the form of the stranded portion 3 of the optical fiber composite overhead wire is not limited to the one shown in FIG. , The type of the metal wire 4, the form of twist, the number of twists, etc.
Can be changed freely.

The following is a specific example. An optical fiber composite overhead wire having the structure shown in FIGS. 1 and 2 was produced. The metal pipe 1 is made of an aluminum alloy having an outer diameter of 5.5 mm and an inner diameter of 4.1 mm, and the wire 5 is made of an aluminum round wire having a diameter of 0.3 mm, 0.4 mm, 0.5 mm, 0.8 mm,
1.5 mm and 3.0 mm were wrapped around the metal pipe 1 in a spiral at an interval D of 4 cm. This optical fiber composite overhead wire was cut into a length of 30 cm, and both ends were sealed with epoxy resin to obtain a sample.

This sample was immersed in a 5% by weight saline solution so that the lower 10 cm was submerged. The corrosion state after immersion was examined by setting the temperature to 55 ° C. and changing the immersion time from 7 days to 72 days. For comparison, a sample in which the stranded portion 3 was directly in contact with the metal pipe 1 without using a wire was also prepared and subjected to the same test. Table 1 shows the results.

[0018]

[Table 1]

In Table 1, the case where crevice corrosion occurred in the metal pipe 1 was evaluated as x, the case where crevice corrosion could not be determined, but corrosion was concentrated in part was evaluated as △, and the case where normal corrosion occurred occurred was evaluated as ○. did. From Table 1, the diameter of the wire 5 was 0.4
It can be seen that by setting the gap between the metal pipe 1 and the stranded wire portion 3 to 0.4 mm or more, that is, the gap corrosion can be prevented.

[0020]

As described above, since the optical fiber composite overhead wire of the present invention has a gap formed between the metal pipe and the stranded portion, the optical fiber composite overhead wire is provided between the metal pipe and the stranded portion. This prevents the occurrence of crevice corrosion, prevents the optical fiber unit housed in the metal pipe from deteriorating, and prevents the transmission loss from increasing. Also, even if the stranded wire corrodes to produce a large-volume corrosive composition, the product spreads into the gaps and does not crush the metal pipe, causing damage to the internal optical fiber unit. Nor.

Further, if means for winding or vertically attaching a wire to a metal pipe for forming the gap is provided,
A gap can be easily formed. In addition, since crevice corrosion can be prevented, it is not necessary to excessively increase the thickness of the optical fiber composite overhead wire.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing an example of an optical fiber composite overhead wire of the present invention.

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal pipe, 2 ... Optical fiber unit, 3 ... Twisted wire part, 4 ... Metal strand, 5 ... Wire

Claims (3)

[Claims] A stranded wire portion formed by twisting a plurality of metal wires around a metal pipe containing an optical fiber, and a gap is formed between the metal pipe and the stranded wire portion. Optical fiber composite overhead wire. 2. The optical fiber composite overhead wire according to claim 1, wherein the gap is 0.4 mm or more. 3. A gap is provided by winding or vertically attaching a wire to a metal pipe.
The optical fiber overhead wire described.