JP2003087953A - Preventing method for breakage and dropping-off of overhead ground wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an economical preventing method for overhead ground wire, capable of preventing an overhead ground wire from dropping off on the ground or transmission lines even if there occurs a lightning stroke high enough to melt all metal strands constituting the overhead ground wire. SOLUTION: In forming the overhead ground wire by twisting metal strands, a fiber bundle is attached to a gap between the fiber strands. In case of breakage of the overhead ground wire, stringing tension is borne by the fiber bundle. The fiber composition is Al2 O3 or SiO2 of 90% or more, or a combination of Al2 O3 or SiO2 with a total of them occupying 90% or more. The length of the fiber line is 1.01 times or more that of the overhead ground wire.

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 an overhead ground wire from breaking and dropping.

[0002]

2. Description of the Related Art An overhead ground wire is installed on the top of a steel tower for a power transmission line (electric power line) and has a function of protecting the power transmission line from damage such as lightning strike. A conventional overhead ground wire will be described in detail below with reference to the drawings.

FIG. 3 is a sectional view of a conventional overhead ground wire.
Reference numeral 11 is an overhead ground wire, and 12 is an element wire (a metal element wire, which will be simply referred to as an element wire hereinafter). The overhead ground wire 11 is formed by twisting six wires 12 around a single wire 12 into a so-called 16-twist. As the element wire 12, a galvanized steel wire or an aluminum covered steel wire is used.

The lightning strike occurs on the main body of the tower, the power transmission line, or the overhead ground wire located above the power transmission line, but in many cases the lightning strikes the overhead ground wire 11. In this way, it is possible to prevent the occurrence of disasters such as blackouts due to direct lightning strikes on power transmission lines. When a lightning strikes the overhead ground wire 11, naturally the wire 12 is melted and broken.

Further, when the lightning strike is large, all the wires 12 are melted and the overhead ground wire 11 is broken. As a result, the overhead ground wire 11 may fall and come into contact with a power transmission line (power line), or may fall on the ground to cause a secondary disaster.

[0006]

[Problems to be Solved by the Invention]
There was a problem explained below.

When a large-scale lightning strike is applied to the overhead ground wire 11, the diameter of the wire 12 is increased or the diameter of the wire 12 is prevented so that the overhead ground wire 11 is not broken to cause a secondary disaster.
It is effective to increase the number of lines, but in such a method the wind pressure increases due to an increase in the weight of the overhead ground wire 11 or an increase in the outer diameter of the overhead ground wire 11. Then, it is necessary to increase the strength of the steel tower itself which connects the overhead ground wire 11 and the power transmission line, which is not economical.

Further, in order to reduce the melting damage at the time of lightning strike, there is a case where a composite wire formed by further plating or extruding zinc on an aluminum-covered steel wire is used as a melting damage layer. Is high and not practical.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and even when a lightning strike occurs that all the wires constituting the overhead ground wire are melted, It is an object of the present invention to provide an economical method for preventing the disconnection and fall of overhead ground wires, which prevents them from falling onto power lines.

[0010]

In order to achieve the above object, the method for preventing the disconnection and fall of an overhead ground wire according to the present invention, in order to achieve the above object, when the metal ground wires are twisted to form the overhead ground wire, the metal ground wire is used. A bundle of fibers was attached to the gap so that the overhead wire tension was borne by the fiber wire when the overhead ground wire was broken.

The fiber component is Al ₂ O ₃ or SiO ₂ 9
0% or more, or a composite of Al ₂ O ₃ and SiO ₂ with a total of 90% or more.

The length of the fiber bundle is 1.01 or more, where the length of the overhead ground wire is 1.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a method for preventing a drop of an overhead ground wire according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a cross-sectional view of an overhead ground wire according to an embodiment of a method for preventing the disconnection and fall of an overhead ground wire according to the present invention. Reference numeral 1 is an overhead ground wire, 2 is an element wire, and 3 is a ceramic fiber wire.

The overhead ground wire 1 is, like the conventional overhead ground wire,
Six strands 2 are twisted in a so-called 16-strand around one strand 2, and the strand 2 is a galvanized steel wire or an aluminum-covered steel wire. A ceramic fiber wire 3 is arranged in a gap between the central wire 2 and the surrounding wire 2.

The ceramic fiber wire 3 is made of Al₂O₃Or Si
O₂Is 90% or more, or Al₂O ₃And SiO₂Compound with
The fiber made of 90% or more of the total of both is properly used.
(For example, dozens or hundreds)
This bundle of fibers is referred to as a ceramic fiber wire in the present invention.
It

The ceramic fiber wire 3 can be manufactured by, for example, the VAD (Chemical Vapor Deposition) method. While bubbling silicon tetrachloride (SiCl4) to deposit soot, at the same time Al ₂ O ₃
Are doped, and the soot base material deposited thereafter is sintered to vitrify, and the glass base material is drawn to obtain fibers. Then, the fibers can be appropriately bundled to form the ceramic fiber wire 3.

When the strands 2 are twisted together, the ceramic fiber lines 3 are inserted between the strands 2 (gap). When the length of the overhead ground wire 1 is 1, the length of the ceramic fiber lines 3 is The feature is that they are added so that the value becomes 1.01 or more.

2A and 2B show an embodiment of the method for preventing the disconnection and fall of an overhead ground wire according to the present invention. FIG. 2A is a front view before the overhead ground wire is broken, and FIG. It is a front view after a ground wire is disconnected. That is, FIG. 2A shows a normal state, and FIG. 2B shows a modeled state in which the overhead ground wire 1 is broken due to a lightning strike.

Before the disconnection, the length of a part of the overhead ground wire 1 is L
However, due to the disconnection of the overhead ground wire 1, the ceramic fiber wire 3 alone bears the overhead wire tension of the overhead ground wire, and the length is increased by L + ΔL and ΔL. Are prevented from falling. However, ΔL
It is configured such that ≧ 0.01 × L.

The overhead wire tension of the overhead ground wire varies depending on the location, but it is several hundred kgf even for a small size overhead ground wire. In order to bear all the load by the ceramic fiber wire 3,
The amount becomes enormous. However, the overhead wire tension can be reduced by making the actual length of the overhead ground wire 1 longer than the length between the steel towers to increase the slack (slack). Therefore, the length of the ceramic fiber wire 3 is 1% less than the length of the overhead ground wire 1.
The length is made longer so that the actual length becomes longer when the overhead ground wire is disconnected.

By arranging the ceramic fiber wires 3 in the gaps between the element wires 2, the ceramic fiber wires 3 have a water retaining effect and, as a result, there is a concern that the corrosion resistance of the element wires 2 may deteriorate. In addition to 3, an anticorrosive agent such as grease may be filled between the wires 2. Since the anticorrosive agent in this case does not affect the tensile strength, it is not included in the percentage of the fibers described in claim 2.

In the embodiment, the overhead ground wire is shown.
OPGW (Opti) that combines optical fiber in the center of overhead ground wire
The same can be applied to cal Fiber Composite Ground Wire). Further, although the ceramic fiber wire 3 is provided as an additional wire between the wires 2, the same effect can be obtained by winding the ceramic fiber wire 3 around the overhead ground wire 1. Further, since the ceramic fiber wire 3 is made of an insulating material, it is also possible to prevent disconnection and drop of the power transmission line by winding it around the power transmission line (power line).

Since the ceramic fiber wires 3 can be arranged between the wires 2 when the wires 2 are twisted together to manufacture an overhead ground wire, the wires 2 can be arranged as in the prior art. It is very economical because there is no need to add another process such as coating zinc with zinc.

Therefore, according to the method for preventing the disconnection and fall of the overhead ground wire according to the present invention, even when a lightning strike occurs that all the wires constituting the overhead ground wire are melted, Never fall on power lines.

[0026]

EFFECTS OF THE INVENTION According to the method of preventing breakage of an overhead ground wire according to the present invention, when forming the overhead ground wire by twisting the metal wires, a bundle of fibers is added to the gap between the metal wires, Since the overhead wire tension is borne by the bundle of fibers when the overhead ground wire is broken, even if a lightning strike occurs that all the wires that make up the overhead ground wire are melted, It is possible to prevent the power line from falling.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an overhead ground wire according to an embodiment of a method for preventing the disconnection and fall of an overhead ground wire according to the present invention.

2A and 2B show an embodiment of a method of preventing a disconnection drop of an overhead ground wire according to the present invention, in which FIG. 2A is a front view before the overhead ground wire is broken, and FIG. It is a front view after disconnection.

FIG. 3 is a cross-sectional view of a conventional overhead ground wire.

[Explanation of symbols]

1 overhead ground line 2 strands 3 Ceramic fiber wire 11 overhead ground line 12 strands

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3B153 AA47 CC44 CC52 FF35 GG01                 5G307 EA01 ED07 EF10                 5G367 LA02

Claims (3)

[Claims] 1. When twisting metal wires together to form an overhead ground wire, a bundle of fibers is attached to a gap between the metal wires, and the wire tension bears the overhead wire tension when the overhead ground wire is broken. A method for preventing the disconnection and fall of an overhead ground wire, which is characterized in that 2. The fiber component is Al ₂ O ₃ or SiO ₂ 9
The method of preventing breakage of an overhead ground wire according to claim 1, wherein 0% or more or a composite of Al ₂ O ₃ and SiO ₂ is 90% or more in total. 3. The method of preventing breakage of an overhead ground wire according to claim 1, wherein the length of the fiber bundle is 1.01 or more when the length of the overhead ground wire is 1.