JPH07122117A - Lightning resistant overhead earth-wire - Google Patents

Abstract

PURPOSE:To prevent short-circuiting to a transmission line in the case where an element wire of an overhead earth-wire is fused by a lightning stroke. CONSTITUTION:An outermost layer of an overhead earth-wire 10 is composed of a plurality of forming element wires 12 which are twisted together. A circumferential direction end face 12a of each forming element wire 12 is formed so as not to coincide with an axis P passing a center 0 of the overhead earth- wire 10 and radially and rectilinearly extending in the radial direction thereof. The circumferential direction end face 12a as an illustrated example is of a stepped shape. Each forming element wire 12 is in a state of being pressed by either of adjoining forming element wires 12 so as not to float up outward in the radial direction. Even when the forming element wire 12 which is attacked by a lightning stroke is fused, since the fused forming element wire 12 is pressed by either of the adjoining forming element wires 12 at parts other than the fused part, wire loosening due to untwisting is not caused. Consequently, short- circuiting caused by the fused forming element wire 12 hanging down and touching an underside transmission line can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning-resistant overhead ground wire.

[0002]

2. Description of the Related Art Conventionally, as an overhead ground wire for a transmission line,
For example, the one shown in FIGS. 5 to 7 is used. The overhead ground wire 1A shown in FIG. 5 is simply a plurality of aluminum-covered steel wires (AC wires) 2 having a circular cross section in which the outer circumference of a steel wire is covered with aluminum. The overhead ground wire 1B shown in FIG. 6 is formed by twisting a plurality of aluminum-covered steel wires 2 having the same circular cross section around the outer circumference of an optical fiber unit 3 in which an optical fiber 3b is housed inside an aluminum pipe 3a. . The overhead ground wire 1C shown in FIG. 7 has a truncated fan-shaped cross section in which an end face 4a in the circumferential direction coincides with an axis P extending radially straight through the center O of the overhead ground wire on the outer circumference of the optical fiber unit 3. The molded wires 4 are twisted together. The overhead ground wires 1B and 1C in FIGS. 6 and 7 are so-called optical fiber composite overhead wires (OPGW).

[0003]

As shown in FIG. 8, an overhead ground wire 1 is installed above a power transmission line 6 which is installed between towers 5, and for that purpose, the wire is melted by a lightning strike. Although it is easy, in any of the conventional structures of the above-mentioned overhead ground wire 1, when the wires such as the aluminum-covered steel wire 2 and the forming wire 4 of the outermost layer are melted by a lightning strike, the wire 2 of the outermost layer is ，
Since there is nothing for restraining 4, the strands 2 and 4 are untwisted and scattered, and the melted strands 2 and 4 hang down as shown in FIG. There was a fear.

The present invention has been made to solve the above-mentioned conventional drawbacks, and even if a part of the wire is broken due to lightning or the like, the broken wire may be twisted back and scattered. It is an object of the present invention to provide a new lightning-resistant overhead ground wire that can eliminate the above-mentioned short circuit risk.

[0005]

A lightning-resistant overhead ground wire of the present invention for solving the above-mentioned problems is a lightning-resistant overhead ground wire that is installed above an overhead power transmission line, and the outermost layer is formed of a plurality of molded strands. In addition to being twisted, it is characterized in that the circumferential end faces of each of the molded wires that are adjacent to and in contact with each other are formed so as not to coincide with the axial line that extends radially through the center of the overhead ground wire in the radial direction. To do.

[0006]

In the above structure, each of the twisted outermost forming strands is formed so that its circumferential end face does not coincide with the axial line extending radially through the center of the aerial ground wire in the radial direction. Therefore, even if each of the forming wires tries to be separated outward in the radial direction, at least a part of the circumferential end surface of the forming wire is engaged with the adjacent forming wire and one of the adjacent forming wires is pressed. Since the wire is held by the wire, it will not untwist and will not come apart. Therefore, it is possible to eliminate the possibility that the blown formed element will hang down and come into contact with the transmission line below and short-circuit.

[0007]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows a first embodiment of the present invention. This overhead ground wire 10 has a structure in which a plurality of molded element wires 12 made of aluminum-covered steel wire are twisted in one layer around the outer circumference of an optical fiber unit 11 containing an optical fiber 11b inside an aluminum pipe 11a. However, the molded wire 12 has a structure including an aluminum coating 12b having a stepped circumferential end face 12a and an internal steel wire 12c matched to the shape.

FIG. 2 shows a second embodiment of the present invention. The overhead ground wire 20 has a structure in which a plurality of molded wires 22 made of aluminum-covered steel wire are twisted in a single layer around the outer circumference of the same optical fiber unit 11 as described above. Is a structure including an aluminum coating 22b having a substantially S-shaped circumferential end surface 22a and an internal steel wire 22c conforming to the shape.

FIG. 3 shows a third embodiment of the present invention. The overhead ground wire 30 has a structure in which a plurality of forming wires 32 made of aluminum-covered steel wire are twisted together in a single layer on the outer periphery of the optical fiber unit 11.
2 is an aluminum coating 32 having a V-shaped circumferential end surface 32a
This is a structure composed of b and an internal steel wire 32c matching its shape.

FIG. 4 shows a fourth embodiment of the present invention. The overhead ground wire 40 has a structure in which a plurality of molded wires 42 made of aluminum-covered steel wire are twisted together in a single layer on the outer periphery of the optical fiber unit 11.
The structure 2 is composed of an aluminum coating 42b having an inclined linear circumferential end surface 42a deviated from the diameter straight line of the overhead ground wire 40, and an internal steel wire 42c conforming to the shape.

Each of the above overhead ground wires 10, 20, 30, 40
In, the twisted forming wires 12, 22, 3
2, 42 are circumferential end faces 12a, 22a, 32a,
42a does not coincide with the axis P extending radially straightly through the center O of the overhead ground wire in the radial direction, and the adjacent forming wires 12, 22, 32, 42 and the circumferential end faces are mutually related. They are joined together and one of the forming wires is pressed by the other adjacent forming wire. Therefore, even if the molded wires 12, 22, 32, 42 that have been hit by a lightning strike are melted, the melted molded wires 12, 22, 32, 4
No. 2 is held by the one of the adjacent forming wires 12, 22, 32, 42 so as not to float outward in the radial direction at a portion other than the fusing point, so that the twist returns and is separated. It does not kick and prevents drooping. Therefore, as shown in FIG. 8, it is possible to reliably eliminate the possibility that the blown formed element wire will contact the lower transmission line and short-circuit.

The forming wire in the overhead ground wire of the present invention is not limited to the cross-sectional shape of the above embodiment. In short, the circumferential end face of the outermost forming wire is
Anything may be used as long as it does not coincide with the axis P that extends through the center of the overhead ground wire and extends radially in a radial direction. As a result, each forming wire is pressed in the radial direction by any one of the adjacent forming wires.

In each of the embodiments, an overhead ground wire consisting of one twisted wire layer has been described. However, in the case of a plurality of twisted wire layers, at least the outermost twisted wire layer has the above-mentioned structure. Formed wire is used. However, the internal twisted wire layer may have a similar structure. Further, in the embodiment, the case of the optical fiber composite overhead ground wire has been described, but it is naturally applicable to a simple overhead ground wire without a built-in optical fiber. Further, although the example shows the case where the forming wire is made of an aluminum-covered steel wire, the forming wire is not limited to this, and a galvanized steel wire, an aluminum wire, a hard copper wire or the like can be used.

[0014]

EFFECTS OF THE INVENTION According to the present invention, each of the twisted outermost forming strands is restrained by one of the forming strands adjacent in the circumferential direction so as not to rise outward in the radial direction. Since the structure has a different structure, even if the formed strand is broken due to a lightning strike, the twist of the formed strand does not return and come apart. Therefore, it is possible to eliminate the possibility that the broken forming element may hang down and come into contact with the lower transmission line, resulting in a short circuit.

In the case of an optical fiber composite overhead ground wire according to a second aspect of the present invention, even if the element wire is broken, it does not come apart, so that the internal optical fiber unit is not exposed and the optical fiber is adversely affected. It is possible to prevent the possibility of reaching.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a lightning resistant overhead ground wire according to a first embodiment of the present invention.

FIG. 2 is a transverse sectional view showing a lightning resistant overhead ground wire according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a lightning resistant overhead ground wire according to a third embodiment of the present invention.

FIG. 4 is a transverse sectional view showing a lightning resistant overhead ground wire according to a fourth embodiment of the present invention.

FIG. 5 is a cross-sectional view showing an example of a conventional lightning-resistant overhead ground wire.

FIG. 6 is a cross-sectional view showing another example of a conventional lightning-resistant overhead ground wire.

FIG. 7 is a cross-sectional view showing still another example of a conventional lightning-resistant overhead ground wire.

FIG. 8 is a diagram illustrating a problem at the time of a lightning stroke of an overhead ground wire.

[Explanation of symbols]

 10, 20, 30, 40 Lightning-resistant overhead ground wire 11 Optical fiber unit 12, 22, 32, 42 Molded wire 12a, 22a, 32a, 42a Circumferential end surface

Claims (2)

[Claims] 1. A lightning-resistant overhead ground wire extended above an overhead power transmission line, wherein the outermost layer is formed by twisting a plurality of molded wires, and the circumference of each molded wire adjacent to and in contact with each other. A lightning-resistant overhead ground wire, characterized in that the directional end face is formed so as not to coincide with an axis extending radially through the center of the overhead ground wire in a radial direction. 2. The lightning-resistant overhead ground wire according to claim 1, wherein the overhead ground wire is an optical fiber composite overhead ground wire in which strands are twisted around the outer circumference of an optical fiber unit containing an optical fiber.