JP2000268636A - Overhead wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overhead wire capable of reducing an aeolian vibration, and both of a wind noise and a corona noise, and simplifying a structure of a wire gripping part. SOLUTION: This overhead wire is composed of a core 1 with a circular cross section formed by concentrically stranding plural strands 4 and an eccentrically stranded wire layer 3 stranded on this core 1. The eccentrically stranded wire layer 3 is formed by arranging and stranding many segment strands 4 with different thickness so as to form its cross section shape into an eccentric circular shape relative to the core 1. Since a spiral waveform is formed on the wire surface, a Karman's vortex is not easily produced, and occurrence of an aeolian vibration and a wind noise can be suppressed. Since there is no protruding bar on the wire surface, a corona is not easily produced and a corona noise can be suppressed. Since the cross section of the wire is circular, the structure of the wire gripping part of an accessory can be same as that of the wire with the circular cross section, and the cost of the accessory can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overhead electric wire with reduced breeze vibration, wind noise, corona noise and wind pressure.

[0002]

2. Description of the Related Art When wind is blown from the side to an overhead electric wire having a circular cross section, Karman vortices are generated on the leeward side of the electric wire, and this causes a small wind vibration when the wind is weak, and an 80 when the wind is strong. It is known that wind noise of ~ 200 Hz is generated. Micro-vibration causes electric wire fatigue damage accident and wind noise causes noise pollution, so it is necessary to reduce it.

[0003] To reduce the breeze vibration and wind noise of an overhead electric wire, the flow of wind around the electric wire may be disturbed to suppress the occurrence of Karman vortices. Therefore, the inventor devised an electric wire in which the outer diameter or thickness of some of the strands twisted to the outermost layer was made larger than the other strands, and a spiral ridge was formed on the outer peripheral surface. (Japanese Unexamined Patent Publication No. 61-116310 and Japanese Utility Model Laid-Open No. 1-152409).

[0004] However, this electric wire has a problem in that corona noise is easily generated during rainfall because a spiral ridge is formed on the outer peripheral surface. Therefore, in order to reduce both the breeze vibration, wind noise and corona noise, a number of wires with different outer diameters or thicknesses are arranged in the outermost layer and twisted by arranging them so that the cross-sectional shape of the outermost layer becomes elliptical. A combined electric wire has been proposed (JP-A-3-196413, JP-A-9-196413).
No. 330617, U.S. Pat. No. 5,171,942). The outer shape of the electric wire is such that the electric wire having an elliptical cross section is twisted, so that the flow of the wind is disturbed and Karman vortex is hardly generated, and corona is hardly generated because there are no ridges on the outer peripheral surface. Therefore, this electric wire can reduce both the breeze vibration, wind noise and corona noise.

[0005]

However, if the cross-section of the electric wire is elliptical, the structure of the electric wire gripping parts of accessories such as an end clamp, a spacer, a damper, etc. becomes complicated, and the cost becomes high. Have difficulty.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to reduce a breeze vibration, both wind noise and corona noise,
In addition, an object of the present invention is to provide an overhead electric wire capable of simplifying the structure of an accessory wire gripping portion.

[0007]

In order to achieve the above object, an overhead electric wire according to the present invention comprises a core having a circular cross section in which a plurality of strands are twisted concentrically, and a plurality of cores having different thicknesses on the core. It is characterized by comprising an eccentric stranded wire layer in which the segment-type strands are arranged and twisted in such a manner that the cross-sectional outer shape becomes a circle decentered with respect to the core. (Claim 1).

With such a configuration, the thick and thin portions of the eccentric stranded wire layer are formed helically in a symmetrical arrangement around the core having a circular cross section, so that the electric wire surface has a wavy shape in the longitudinal direction. Will be hit. For this reason, the flow of the wind blown to the electric wires is disturbed, and Karman vortices are less likely to be generated, and corona is less likely to be generated because there are no ridges on the outer peripheral surface. Furthermore, since the cross-sectional shape of the electric wire is circular, the structure of the electric wire gripping portion of the accessory is substantially the same as that of the electric wire having a circular cross-section and is simple.
In addition, the wind pressure can be reduced as compared with an elliptical wire.

Further, in the overhead electric wire of the present invention, when the maximum thickness of the segment-shaped strand constituting the eccentric stranded wire layer is d ₂ and the minimum thickness is d ₁ , d ₂ / d ₁ is 2 to 5. It is preferably within the range (claim 2).

The overhead electric wire according to the present invention has a configuration in which the outer peripheral surface of the segment-shaped wire constituting the maximum thickness portion protrudes from the outer peripheral surface of the other segment-shaped wire having a circular cross section. (Claim 3).

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. [Embodiment 1] FIGS. 1 and 2 show an embodiment of the present invention. In the drawing, reference numeral 1 denotes a core having a circular cross section formed by concentrically twisting a required number of wires 2 having the same outer diameter, and 3 denotes an eccentric stranded wire layer provided on the core 1. The eccentric stranded wire layer 3
A required number of segment-type wires 4 having different wall thicknesses are arranged and twisted such that a cross-sectional outer shape (a contour circumscribing each segment-type wire 4) is a circle eccentric to the core 1. . The element wires 2 forming the core 1 are, for example, steel wires (galvanized steel wires, aluminum-coated steel wires, etc.), and the segment type wires 4 forming the eccentric stranded wire layer 3 are, for example, aluminum wires (including aluminum alloy wires). ).

With the above configuration, the surface of the electric wire has a wavy shape in the longitudinal direction as shown in FIG. 2 (the thick and thin portions of the eccentric stranded wire layer 3 are wave peaks). And valleys are formed in a spiral shape), the flow of the wind is disturbed, and Karman vortices are less likely to be generated. In addition, since there is no ridge on the outer peripheral surface, corona hardly occurs, and corona noise can be reduced. Furthermore, since the cross-sectional shape of the wire is circular, the structure of the wire gripping part of the accessory is
It can be substantially the same as an electric wire having a circular cross section and is simple, so that the cost of accessories can be reduced. FIG. 2 shows the twist pitch of the eccentric twisted layer 3 small in order to exaggerate the shape of the wire surface. Depending on the case, it is about 7 to 15 times the outer diameter of the electric wire.

In the electric wire having the above configuration, the thickness d ₂ of the thickest segment-type wire among the segment-type wires 4 constituting the eccentric stranded wire layer 3 and the thickness d ₂ of the thinnest segment-type wire. The outer diameter d ₁ may be set so that d ₂ / d ₁ is 2 to 5. For example, if d ₁ is 2.5 mm, d
₂ is 5 to 12.5 mm. The reason for this is to increase the amount of eccentricity δ of the center of the circumcircle of the eccentric stranded wire layer 3 with respect to the center of the core 1 as much as possible to increase the change in the waveform of the electric wire surface. There is a restriction that d ₁ cannot be made too small from the viewpoint of corrosion protection strength.

[Embodiment 2] FIG. 3 shows a second embodiment of the present invention. In this overhead electric wire, the thicker wire (at least the wire having the largest thickness) among the wires 4 constituting the eccentric stranded wire layer 3 is constituted by the segment stranded wires 4a.
The reason for this is that the stranded eccentric wire layer 3 is easily twisted by forming the thicker strand with a segmented stranded wire having a lower rigidity than a single wire. In addition, by using the thicker strand as the segment stranded wire, the maximum thickness d ₂ of the eccentric stranded wire layer 3 can be increased, so that the change in the waveform of the electric wire surface can be increased and the wind noise suppressing effect can be enhanced. It is also possible. The configuration other than the above is the same as that of the first embodiment.

[Embodiment 3] FIG. 4 shows a third embodiment of the present invention. In this overhead electric wire, an eccentric stranded wire layer 3 is formed by twisting a large number of segment-type strands 4 having different thicknesses around an outer periphery of a core 1 having a circular cross section. The thicker portion of the eccentric stranded wire layer 3 twists the segment type wires 4 into two layers. The reason for this is that, similarly to the second embodiment, the cross-sectional area per one of the segment type strands 4 is reduced to facilitate the twisting of the eccentric stranded layer 3 and the maximum thickness of the eccentric stranded layer 3 is increased. This is to increase the change in the waveform on the wire surface.

This overhead electric wire has the same effects as those of the first and second embodiments, and also has the effect of reducing the wind pressure due to its smooth surface. To increase the wind pressure reduction effect,
It is also effective to roughen the surface of the electric wire and to form a large number of dimples on the surface of the electric wire. Also, by forming a groove having an appropriate width and depth at the boundary between the segment-shaped wires 4 on the surface of the electric wire, it is possible to enhance the wind noise reduction effect and the wind pressure reduction effect. The configuration other than the above is the same as that of the first embodiment.

[Embodiment 4] FIG. 5 shows a fourth embodiment of the present invention. This overhead electric wire has the eccentric stranded wire layer 3 composed of the segment type wires 4 as in the third embodiment.
The difference from the third embodiment is that the outer peripheral surface of the segment-shaped element wire 4a constituting the thickest portion of the eccentric stranded wire layer 3 is stepped from the outer peripheral surface of the other segment-shaped element wire 4 having a circular cross section. That is, it protrudes by t.

In this way, the low wind noise effect can be enhanced with a lower step t. That is, the step t is 0.4
About 0.9 mm. Note that the step t is 1.0 mm
It has been confirmed by wind tunnel experiments that the above-mentioned characteristics degrade the oblique wind characteristics. For example, in the case of an oblique wind angle of 60 °, it is almost the same as a conventional wire having a circular cross section. In addition, the central angle θ of the portion where the step t is provided is preferably about 15 ° to 120 °. If θ is small, the effect of disturbing the Karman vortex decreases,
It is not preferable because not only does the wind noise reduction effect decrease, but also sharp projections cause corona noise. If θ exceeds 120 °, the effect of the step is lost, the wind noise characteristic and the wind pressure characteristic are substantially equivalent to those of the electric wire whose diameter is simply increased, and the merit of providing the step is lost. Therefore, θ is appropriately in the above range, and is preferably set to about 45 ° for practical use.

[0019]

As described above, according to the present invention, a spiral waveform is formed on the surface of the electric wire by the thick and thin portions of the eccentric stranded wire layer. Is disturbed and Karman vortices are less likely to be generated, and the generation of micro-wind vibration and wind noise can be suppressed. Further, since there is no high ridge on the electric wire surface unlike the conventional low wind noise electric wire, corona hardly occurs and corona noise can be reduced. Further, since the cross-sectional outer shape of the electric wire is circular, the structure of the electric wire grip portion of the accessory may be substantially the same as that of the electric wire having a circular cross section, and the cost of the accessory can be reduced. It also has the effect of reducing wind pressure.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of the overhead electric wire of FIG. 1;

FIG. 3 is a sectional view showing a second embodiment of the overhead electric wire according to the present invention.

FIG. 4 is a cross-sectional view showing a third embodiment of an overhead electric wire according to the present invention.

FIG. 5 is a sectional view showing a fourth embodiment of an overhead electric wire according to the present invention.

[Explanation of symbols]

 1: core 2: strand 3: eccentric stranded layer 4: segment type strand 4a: segment strand 4b: segment type strand having a step

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[Procedure amendment]

[Submission date] May 26, 2000 (2005.2.
6)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

Claims (3)

[Claims] 1. A core having a circular cross section in which a plurality of strands are twisted concentrically, and a plurality of segment-type strands having different thicknesses are eccentric on the core with respect to the core. An overhead electric wire comprising an eccentric stranded wire layer arranged and twisted in a circular shape. 2. When the maximum thickness and the minimum thickness of the segment type strands constituting the eccentric stranded wire layer are d ₂ and d ₁ , respectively, d ₂ / d
Overhead conductors according _to claim 1, wherein ₁ is characterized in that in the range of 2-5. 3. An outer peripheral surface of a segment-shaped element wire constituting a maximum thickness portion protrudes from an outer peripheral surface of a circular section formed by other segment-type element wire. 2. The overhead electric wire according to 2.