JPH0847149A - Corrosion prevention for tower-top part of optical fiber composite overhead earth-wire - Google Patents

Abstract

PURPOSE:To prevent an aluminum pipe from being corroded by salty water entering a gap between metallic wires, and the pipe and the metallic wire from being electrolytically-corroded by salty water and action of induced current, by covering the outside of the metallic wire in a non-tense part with a waterproof cover for shutting down water content. CONSTITUTION:A waterproof cover 3 is provided so as to cover a non-tense part between a tension resisting clamp 2 and a steel tower ground clamp 4 which are liable, to corrode. By winding an armor rod around the outside of the waterproof cover 3, an overhead earth-wire 1 is protected doubly. It is thus possible to prevent salty water from adhering to the overhead earth-wire 1 in the non-tense part due to wind and rain, an aluminum pipe from being corroded by salty water, and the pipe and the metallic wire from being electrolytically-corroded by salty water and action of induced current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing corrosion of a tower top of an optical fiber composite overhead ground wire.

[0002]

2. Description of the Related Art FIG. 4 is a cross-sectional view showing an example of a conventional optical fiber composite overhead ground wire (hereinafter sometimes abbreviated as OPGW).

In FIG. 4, 1 is OPGW, 9 is an optical fiber cable, 10 is an aluminum pipe, 11 is a spacer for fixing the optical fiber cable in the aluminum pipe, and 12 is a metal wire. The OPGW shown in FIG. 4 is an OPGW composed of a metal wire 12 having a single layer structure.
Is.

As the optical fiber cable 9, an optical fiber cable in which a glass fiber or a plastic fiber is coated with a resin or the like is used. Usually, a glass fiber optical fiber having a single core or a stranded wire is used.

The spacer 11 is usually made of a material such as aluminum, aluminum alloy, resin or sponge. The spacer may not be used in some cases.

As the metal wire 12, an aluminum-coated steel wire in which a steel wire is clad with aluminum is generally used, but an aluminum wire or an aluminum alloy wire may be used.

FIG. 5 is a schematic side view of the top part of a draw tower tower in a conventional installation example using the OPGW.

In FIG. 5, 1 is an OPGW, 2 is a tension clamp, 13 is an armor rod wound around the metal wire of OPGW in the tension clamp 2, 4 is a steel tower ground clamp, 5 is a steel tower, 6 Indicates a detention fitting, OPGW
The OPGW between the tension-resistant clamp 2 at the top of the tower 1 and the steel tower grounding clamp 4 forms a non-tensioned portion and is grounded via the steel tower grounding clamp 4.

In FIG. 5, the armor rod is wound around the OPGW 1 near the clamp portion by the tightening pressure of the tension clamp 2 for the purpose of protecting the OPGW 1 from scratches, for example. In some cases, the armor rod is not used.

In the tension portion of the OPGW 1, the metal wire 12 is arranged on the outer circumference of the aluminum pipe 10 without a gap due to a tension load. Therefore, for example, when the power transmission line is near the coast, even if water containing salt adheres to the surface of the OPGW 1 due to wind and rain in the tension part of the OPGW 1,
Since water containing salt does not enter from the gap between the metal wires due to wind and rain, corrosion of the aluminum pipe 10 does not occur.

However, in the non-tensioned portion of the OPGW1,
The OPGW is curved to ground to the steel tower grounding clamp 4, and the looseness due to no tension causes a gap between the metal wires. When salty water adheres to the surface of the OPGW due to wind and rain, the metal wire 12
In the case of a single-layer structure, water containing salt infiltrates through the gaps between the metal wires, adheres to the surface of the aluminum pipe, and the aluminum pipe is corroded by the water containing salt.

An induced current flows through the OPGW 1 under the influence of a current flowing through a power line (not shown) arranged in parallel. The induced current is OPGW in the tension section.
1, the metal wire 12 and the aluminum pipe 10
Since the current flows with a current distribution according to the permittivity, the current hardly moves between the aluminum pipe and the metal wire arranged on the outer periphery of the aluminum pipe. But,
At the top of the tower 5, the OPGW 1 is electrically connected to the tower grounding clamp 4 and grounded in order to cancel the induced current flowing into the non-tensioned portion or for lightning protection during a lightning strike. The induced current is OPG at the ground
Since the steel tower grounding clamp 4 and then the steel tower 5 come in and go out through the metal wire forming W1, the OPGW is near the grounding portion.
Since the distribution of the induced current is disturbed between the aluminum pipe and the metal wire that form the element and a potential difference occurs, a current flows between the aluminum pipe and the metal wire. Further, the OPGW is generally in a tension-free state and curved at the top of the tower, and the electrical contact between the aluminum pipe 10 and the metal wire 12 forming the OPGW is likely to be unstable.

Therefore, for example, when the power transmission line is close to the coast, if moisture containing salt infiltrates with rainwater or the like from the gap between the metal wires of the OPGW 1 in the non-tensioned portion of the tower top, the moisture containing the salt. Current flows in and out between the aluminum pipe and the metal wire via the, resulting in significant electrolytic corrosion of the aluminum pipe and the metal wire.

When electrolytic corrosion occurs on the metal wire 12, its original mechanical strength, conductivity, etc. are lost.
Further, when electrolytic corrosion occurs in the aluminum pipe 10, it eventually becomes a hole penetrating to the inside, which may adversely affect the optical fiber inserted in the aluminum pipe such as an increase in transmission loss and core breakage.

[0015]

The object of the present invention is to provide an OP
In the non-tensioned portion of the top of the GW, for example, when the transmission line is close to the coast, it is possible to prevent water containing salt from adhering to the surface of the non-tensioned portion due to wind and rain, and to remove the salt from the gap between the metal wires. Preventing aluminum pipes from being corroded by salty water due to intrusion of water containing them and electrolytic corrosion of aluminum pipes and metal wires by the action of salty water and the induced current. It is in.

[0016]

SUMMARY OF THE INVENTION The present invention is a tower for an optical fiber composite overhead ground wire (OPGW), which comprises an aluminum pipe having an optical fiber inserted therethrough and a metal wire arranged on the outer periphery of the aluminum pipe. In a tension-free portion between tension-clamps at the top, a waterproof cover is provided on the outside of the metal wire of the tension-free portion to block moisture, and to a method for preventing corrosion at the top of a tower of an optical fiber composite overhead ground wire. .

According to the present invention, moisture can be blocked by covering the outside of the metal wire of the tension-free portion of the OPGW with a waterproof cover, so that, for example, when the power transmission line is near the coast, it contains salt due to wind and rain. The water does not adhere to the OPGW in the non-tensioned portion, the aluminum pipe is corroded by the salty water, and the aluminum pipe and the metal wire are electrolytically corroded by the action of the salty water and the induced current. Highly reliable O
A PGW can be provided.

[0018]

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

FIG. 1 shows the above-mentioned O in one embodiment of the present invention.
It is a schematic side view of the draw tower tower top part of PGW1. In FIG. 1, 1 is an OPGW, 2 is a tension clamp, 3 is a waterproof cover that is coated on the outside of the metal wire of the OPGW in the tension-free part at the top of the tower, 4 is a steel tower ground clamp, 5 is a steel tower, and 6 is an anchor. Shows the metal fittings. The tower top of the OPGW forms a non-tensioned portion and is grounded via a steel tower grounding clamp 4.

The waterproof cover is provided so as to cover at least the non-tensioned portion of the OPGW between the tension-resistant clamp 2 and the steel tower grounding clamp 4 which easily corrode. Therefore,
The tension clamp 2 may be slightly extended to the tension portion.

Conventionally, the OPGW of the tension-resistant clamp portion is generally wound with an armor rod for the purpose of protecting it by the tightening pressure of the tension-resistant clamp so as not to be scratched. . However, according to the present invention, by extending the waterproof cover 3 to the tension clamp portion, the OPGW of the tension clamp portion can be protected, for example, from being scratched. OP is obtained by further winding an armor rod on the outside of the waterproof cover.
The GW can be protected twice. Further, a waterproof cover may be further coated on the outside of the armor rod.

According to the present invention, since the waterproof cover is covered only on the non-tensioned portion, corrosion can be sufficiently prevented, and therefore the cost is excellent.

FIG. 2 is a sectional view taken along line aa of the OPGW in FIG. 1 in which the waterproof cover is covered on the outside of the metal wire. In FIG. 2, 3, 9 to 12 indicate the same members as described above. By covering the outer side of the metal wire 12 with the waterproof cover 3, the aluminum pipe 10 and the metal wire 12 constituting the OPGW 1 can be shielded from water containing salt due to wind and rain.

FIG. 3 shows an OP according to another embodiment of the present invention.
It is a schematic side view of the connection steel tower tower top part of GW. In FIG. 3, 1 to 6 represent the same members as described above, 7 represents a jumper wire, and 8 represents a connection box for connecting the OPGW 1. O
The PGW 1 is curved and pulled down in the non-tensioned portion at the top of the tower in order to connect the optical fibers using the connection box 8. The waterproof cover 3 covers the OPGW 1 so as to include at least a curved portion from the portion of the tension clamp 2 to the junction box 8 or from the portion of the tension clamp 2 to the junction box 8. Further, as in the case of the tower portion (FIG. 1) of the draw tower, the waterproof cover may be slightly extended from the tension clamp 2 to the tension portion.

In FIG. 3, the cross section of the OPGW in which the waterproof cover is covered on the outside of the metal wire is not shown, but it is similar to that of FIG. 2, and the waterproof cover is covered on the outside of the metal wire of the non-tensioned portion. As a result, the aluminum pipe and the metal wire forming the OPGW can be shielded from the salt-containing water caused by wind and rain.

The waterproof cover according to the present invention has a form that prevents moisture or the like from entering the non-tensioned portion of the OPGW.
It may have any shape. For example, even if it is formed by directly winding it on the outside of a metal wire as shown in FIG.
It may be formed in a pipe shape so as to cover the metal wire with a space left therebetween.

As the material of the waterproof cover used in the present invention, any material having a waterproof effect may be used, and resin, rubber, metal or the like may be used. Examples of the resin include polyethylene, polypropylene, polyvinyl chloride and the like, and polyethylene and polyvinyl chloride are preferable in terms of moldability and durability. Examples of the rubber include ethylene propylene rubber and the like. Furthermore, examples of the metal include electromagnetic soft iron, aluminum, nickel, and stainless steel, and electromagnetic soft iron is preferable from the viewpoint of preventing the generation of the induced current. When the electromagnetic soft iron is used as the material of the waterproof cover, the induction current can be prevented from occurring, and the aluminum pipe and the metal wire can be more reliably prevented from being corroded. As the metal, it is preferable to use a metal that has been subjected to anticorrosion treatment in advance, from the viewpoint of preventing corrosion of the waterproof cover itself. Examples of the anticorrosion treatment of the metal include baking coating and polyethylene coating.

Examples of the shape of the waterproof cover used in the present invention include a tape shape, a pipe shape, a box shape, and a corrugated shape.

As the method of covering the waterproof cover in the present invention, for example, a method of directly winding a tape-shaped material on the outside of the metal wire of OPGW, a pipe-shaped or box-shaped cover having a half-divided structure is attached to OPGW. There are ways to do it. When the tape-shaped material is used, for example, an electromagnetic soft iron tape having a width of about 40 mm and a thickness of about 0.5 mm may be wound around the OPGW, and coal tar or the like may be applied to the tape from the viewpoint of corrosion protection.

In the present invention, the end portion of the waterproof cover may be sealed with putty or the like by winding a tape or the like. However, the cover is at least the highest OPGW metal at the top of the tower. Since it is coated on the outside of the wire, salt-containing water does not infiltrate from the end to the non-tensioned portion of the OPGW even if no special end treatment is applied.

According to the present invention, moisture can be blocked by covering the outer side of the metal wire of the tension-free portion of the OPGW with a waterproof cover. Therefore, for example, when the power transmission line is close to the coast, it contains salt due to wind and rain. The water does not adhere to the OPGW in the non-tensioned portion, the aluminum pipe is corroded by the salty water, and the aluminum pipe and the metal wire are electrolytically corroded by the action of the salty water and the induced current. Highly reliable O
A PGW can be provided.

Further, in advance, a film having corrosion resistance is formed on the surface of the aluminum pipe by anodizing treatment by anodizing treatment, boehmite treatment, other chemical conversion treatment, and the like, and further, fine pores existing in the coating are sealed. It is preferable that the corrosion of the aluminum pipe is more reliably prevented. The anticorrosion treatment of the aluminum pipe may be performed on the tape-shaped aluminum before pipe making or on the aluminum pipe after pipe making.
Further, the anticorrosion treatment of the aluminum pipe may be applied to the entire length of the aluminum pipe, but in order to prevent corrosion due to water containing salt or induced current, it is sufficient to apply it to the non-tensioned portion. .

Further, it is preferable to coat the surface of the aluminum pipe with a resin or rubber in advance in order to more surely prevent the corrosion of the aluminum pipe. Examples of the resin include polyethylene, polyvinyl chloride, polypropylene and the like, and polyethylene is preferable from the viewpoint of durability. Further, examples of the rubber include ethylene propylene rubber. Examples of the coating method include extrusion coating, coating and winding.

Further, it is also preferable to fill the space between the metal wires forming the OPGW with grease in order to more reliably prevent the corrosion of the aluminum pipe. As the grease, grease for anticorrosion electric wire is generally used, but silicone grease is preferably used from the viewpoint of heat resistance and the like. The grease can be applied, for example, by applying it at the time of manufacturing the electric wire, applying it at the time of overhead line construction, or applying it after the overhead line construction. From the viewpoint of workability, it is applied at the time of overhead line construction. The method of doing is suitable.

According to the present invention, the corrosion of the aluminum pipe and the metal wire can be further prevented only by applying the anticorrosion treatment of the various aluminum pipes and the metal wire to only the non-tensioned portion.

Further, when a prefabricated electric wire is used for the overhead wire, since it is easy to identify the portion which becomes the non-tensioned portion before the overhead wire construction, the aluminum pipe is preliminarily subjected to alumite treatment, boehmite treatment, other chemical conversion treatment, etc. To form a film with corrosion resistance, and further apply anticorrosion treatment by subjecting the micropores present in the film to sealing treatment, or anticorrosion treatment by coating the aluminum pipe surface with resin in advance only on the parts that will be the non-tensioned portion. Since it can be applied easily, it is particularly excellent in terms of workability and cost. As an example of the tower top of the OPGW installed using the prefabricated electric wire, there is the connecting tower top shown in FIG.

Incidentally, as shown in FIG. 3, a jumper wire is provided between the tension clamp and the steel tower grounding clamp, and grounding is performed through the steel tower grounding clamp, whereby direct lightning strike to the OPGW can be avoided.

[0038]

According to the present invention, moisture can be blocked by covering the outer side of the metal wire of the non-tensioned portion of the OPGW with a waterproof cover. Therefore, for example, when the power transmission line is close to the coast, salt content is caused by wind and rain. OPGW of water containing water is a tensionless part
The aluminum pipe can be prevented from being corroded by water containing salt, and the aluminum pipe and the metal wire can be prevented from being electrolytically corroded by the water containing salt and the action of the induced current. It is possible to provide a highly reliable OPGW.

[Brief description of drawings]

FIG. 1 is a schematic side view of a top portion of a draw tower of an optical fiber composite overhead ground wire according to an embodiment of the present invention.

2 a of an optical fiber composite overhead ground wire in FIG. 1 in which a waterproof cover according to the present invention is coated on the outside of a metal wire.
FIG.

FIG. 3 is a schematic side view of a connecting tower top portion of an optical fiber composite overhead ground wire in another embodiment of the present invention.

FIG. 4 is a cross-sectional view showing an example of a conventional optical fiber composite overhead ground wire.

FIG. 5 is a schematic side view of a conventional steel fiber tower overhead portion of an optical fiber composite overhead ground wire.

[Explanation of Codes] 1 Optical Fiber Composite Overhead Ground Wire 2 Tension Clamp 3 Waterproof Cover 4 Steel Tower Grounding Clamp 5 Steel Tower 6 Retractor 7 Jumper Wire 8 Junction Box 9 Optical Fiber Cable 10 Aluminum Pipe 11 Spacer 12 Metal Wire 13 Optical Fiber Composite Armor rod wrapped around the metal wire of the overhead ground wire

Claims (1)

[Claims] 1. A non-tensioned portion between tension-tight clamps at the top of a tower of an optical fiber composite overhead ground wire consisting of an aluminum pipe having an optical fiber inserted therethrough and a metal wire arranged on the outer periphery of the aluminum pipe. A method for preventing corrosion of the tower top of an optical fiber composite overhead ground wire, characterized in that a water-proof cover is provided on the outside of the metal wire of the non-tensioned portion to block moisture.