JPH09330617A - Overhead wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overhead wire which is used for an overhead transmission line, an overhead earth-wire, etc., and is small in AN(audible noise) and besides can reduce wind sound and wind load, and to which snow hardly adheres. SOLUTION: A wire consisting of an inner layer round in cross section where layers are made in coaxial form by interwiding round element wires 4 of aluminum or aluminum alloy around a steel core 1, and an outermost layer which is in contact with the inner layer and is made by intertwining round element wires 6 of aluminum or aluminum alloy different in diameter is elliptic in cross section, and especially the element wires in the outermost layer are arranged symmetrically about the longitudinal axis, and besides the element wires with the largest diameters in a pair are arranged on both sides of the longitudinal axis. Corona noise can be reduced by such arrangement of the element wires in the outermost layer, and also the area of projection can be made small and besides it can be made streamlined though the conductor has an area equivalent to a conventional cable round in cross section, so the wind load can be reduced. This sectional form is also effective to the measure against noise and snow adhesion.

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 used for an overhead power transmission line, an overhead ground wire and the like.

[0002]

2. Description of the Related Art Typical configurations of electric wires used for overhead power transmission lines are shown in FIGS. FIG. 7 shows an ACSR having a circular cross section (correctly referred to as a circle although the outer contour is circular, hereinafter referred to as a circle) obtained by twisting circular strands 2 around a steel core 1, a nominal cross sectional area of 810 mm ² , and an outer diameter of 38. It is 4 mm. ACS
In R, a steel core, which is formed by twisting steel wires as a tension member, is arranged at the center, and aluminum or aluminum alloy wires are twisted around it to form a concentric layer. Depending on the application, zinc is added to the steel wire. A plated or aluminum-coated steel core or a steel core formed by twisting Invar steel wires is used. FIG.
Is an example of improving the space factor by using non-circular shaped wire,
AC with a circular cross section formed by concentrically forming a layer around the steel core 1 by a non-circular forming wire 3 of aluminum or aluminum alloy
It is SR. In this case, the cross-sectional area of the conductor is 810 mm ² , which is the same as that of the electric wire in FIG. 7, but the outer diameter is reduced to 35.3 mm. The nominal cross-sectional area is expressed by the cross-sectional area of a conductor (aluminum or aluminum alloy) that does not include a steel core.

[0003]

Since the electric wire shown in FIGS. 7 and 8 has a circular cross section, wind noise is generated and becomes noise. Further, the wind load is reduced in the electric wire of FIG. 8 as compared with the electric wire of FIG. 7 due to the diameter reduction, but on the other hand, corona noise becomes a problem.
Corona noise is AN due to corona discharge generated during rainfall.
(Audible noise), the larger the potential gradient on the surface of the wire, the more likely it is to occur and the larger. Therefore, in the case of the electric wire shown in FIG. 8, AN is increased because the potential gradient increases due to the diameter reduction. To solve these problems, 1. To reduce the wind load, it is better to make the projected area of the electric wire smaller and make the cross-sectional shape closer to the streamline shape. 2. On the other hand, in order to reduce AN, it is better that the outer diameter of the wire is large. 3. A circular cross section is not desirable to reduce wind noise and vibration. 4. In addition, a non-circular cross section is effective in reducing snow accretion to prevent snow accretion on electric wires. As an electric wire which satisfies the above requirements, an electric wire having an elliptical cross-sectional shape (correctly, the envelope outer shape is an ellipse, but hereinafter referred to as an ellipse) as shown in FIG. 4 is conceivable. However, it has been found that a sufficient effect cannot be achieved only when the sectional shape is an ellipse. The present invention is used for overhead power lines, overhead ground lines, etc.
It is an object of the present invention to provide an overhead wire that has a small AN, can reduce wind noise and wind load, and is unlikely to snow.

[0004]

According to the present invention, strands are twisted around a steel core to form concentric layers to form an inner layer having a circular cross section, and an outermost layer in contact with the inner layer is formed outside the inner layer. As a result, the cross-sectional shape of the electric wire is formed into an ellipse having the following requirements or an ellipse close to the ellipse (this is a substantially ellipse). For the outermost layer, use wires of different sizes, that is, circular wires with different diameters, and non-circular wires with different cross-sectional sizes. Deploy. The strands of the outermost layer are arranged symmetrically with respect to the major axis of the ellipse or substantially the ellipse in cross section, and the major axis passes through the pair of maximum strands instead of penetrating the maximum strand, Therefore, the largest strands are arranged symmetrically with the long axis in between. Aluminum or aluminum alloy is suitable for the material of the wire. Also, to achieve the optimum effect by constructing the electric wire so that the ratio (b / a) of the long diameter (a) and the short diameter (b) in the cross-sectional shape is in the range of 1 / 1.2 to 1 / 1.8. You can The practical range of this ratio is the range of 1 / 1.2 to 1 / 1.7 due to design reasons described later, and the most preferable range in terms of characteristics is the range of 1 / 1.2 to 1 / 1.5. By arranging the wires of the outermost layer in this way, A
While improving N (audible noise), wind noise,
Vibration and wind load can also be improved.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION One configuration example of the present invention will be described with reference to FIG. Aluminum or aluminum alloy circular element wires 4 are twisted around a steel core 1 to form concentric layers to form an inner layer having a circular cross section. The outermost layer in contact with the inner layer is formed by twisting circular element wires 6 of aluminum or aluminum alloy having different diameters so that the electric wire has an elliptical cross section.
However, in this example, unlike the example of FIG.
A pair of wires having the maximum diameter are paired on both sides (upper and lower in the figure) of the long axis, that is, the long axis does not pass through the wires and are arranged symmetrically with respect to the long axis. In the example of FIG. 4, one of the wires of the maximum diameter among the wires of the outermost layer is vertically symmetrically arranged with the long axis passing through. In the example of FIG. 1, the major axis is 38.4 mm,
It has a minor axis of 30.3 mm and a sectional area equivalent to that of ACSR610 mm ² . For this reason, the outer diameter of ACSR 610 mm ² of a circular electric wire formed by twisting circular element wires is 3
4.2 mm. In addition, since the wires are twisted in the longitudinal direction, the cross-sectional shape turns in the longitudinal direction, so it is difficult to secure the shape if the cross-sectional shape is elliptical from the inner layer, and the manufacturing technology is also sophisticated. This increases the manufacturing cost. Therefore, an inner layer having a circular cross section is formed, and then wires having different diameters are twisted together to form an elliptical cross section.

The second configuration example shown in FIG. 2 is an example using a non-circular shaped element wire. A non-circular shaped element wire 5 of aluminum or aluminum alloy is twisted around the steel core 1 to form concentric layers to form an inner layer having a circular cross section. The outermost layer in contact with the inner layer is formed by twisting non-circular shaped strands 7 of aluminum or aluminum alloy having different sizes so that the electric wire has an elliptical cross section. Also in this case, as in the example of FIG. 1, with respect to the wires in the outermost layer, the long axis passes between the maximum wires and the wires are arranged vertically symmetrically with respect to the long axis.
The electric wire shown in FIG. 2 has a major axis of 38.4 mm and a minor axis of 32.0 m.
m, the cross-sectional area of the conductor is 810 mm ² , but the equivalent diameter is 35.5 mm, which is almost the same as the outer diameter of the conventional circular electric wire having the reduced diameter shown in FIG. The projected area of can be achieved. The equivalent diameter is a diameter when converted into an electric wire having a circular cross section with the same cross sectional area.

A third configuration example shown in FIG. 3 is an example in which a non-circular shaped element wire and a circular element wire are combined. A non-circular shaped element wire 5 of aluminum or an aluminum alloy is twisted around the steel core 1 to form a concentric layer to form an inner layer having a circular cross section.
The outermost layer in contact with the inner layer is formed by twisting circular element wires 6 of aluminum or aluminum alloy having different diameters so that the electric wire has an elliptical cross section. Also in this case, the outermost layer wire is symmetrical with respect to the long axis by the same arrangement as in FIGS. 1 and 2. FIG. 3 shows a major axis of 38.4 mm and a minor axis of 30.
It has a sectional area equivalent to 0 mm and ACSR680 mm ² .

The following table shows the results of comparative experiments with the conventional electric wire for the AN and wind noise reduction effects of the electric wire having the structure shown in FIG. 4 and the electric wire having the structure of the present invention. AC for conventional wires
SR810 mm ² (FIG. 7) was used, and the electric wire having the configuration of FIG. 4 and the electric wire of the present invention, which had an ellipse (a major axis is a and a minor axis was b) having a cross-sectional area equivalent to this, were used. Table 1 shows the evaluation results of AN of the electric wire having the configuration of FIG. 4 with respect to the conventional electric wire.

[Table 1] (1) Evaluation B: Within +3 dB relative to the AN level of the conventional electric wire C: Within +5 dB relative to the AN level of the conventional electric wire D: Greater than 5 dB relative to the AN level of the conventional electric wire

Table 2 shows the evaluation results for AN of the electric wire having the constitution of the present invention shown in FIG. 1 with respect to the conventional electric wire (FIG. 7).

[Table 2] (1) Evaluation A: It is superior to the AN level of conventional electric wires. B: Within +3 dB with respect to the AN level of the conventional electric wire. C: Within +5 dB with respect to the AN level of the conventional electric wire. D: Greater than 5 dB with respect to the AN level of the conventional electric wire.

Table 3 shows the evaluation results of the conventional electric wire with respect to the wind noise reduction effect, and regarding this result, no difference was found between the electric wire having the constitution of FIG. 4 and the electric wire of the present invention.

[Table 3] (1) Evaluation A: There is a reduction effect of 5 dB or more over the conventional electric wire. B: There is a reduction effect of 3 to 5 dB as compared with the conventional electric wire. C: There is a reduction effect of 0 to 3 dB as compared with the conventional electric wire.

Compared with conventional electric wires, the same or higher at the AN level, A or B in the evaluation of Tables 1 and 2, 3 to 5 dB or more in the wind noise reduction effect, and A or B in the evaluation of Table 3. Then, with the electric wire having the configuration shown in FIG. 4, from Tables 1 and 3, it is not possible to achieve even with b / a = 1 / 1.1. Note that the reason why B is included in the evaluation is that 3 dB indicates a double value as the sound energy, and clearing this value is the basis of noise countermeasures. According to the configuration of the present invention, from the characteristics shown in Tables 2 and 3, b / a = 1 / 1.2 to 1
The target can be achieved at /1.8. The reason will be described below. In the configuration of FIG. 4, as shown in FIG. 5 (a), large water droplets are attached during rainfall, so that the water drainage property is poor and the AN characteristic is not improved. However, according to the configuration of FIG. As shown in (b), since the water droplets are small, the AN characteristic is improved. Also in the configuration of the present invention shown in FIG. 2, the shape of the water droplets is likewise shown in FIG.
As shown in (b), the wire having the maximum diameter arranged on both sides of the long axis is originally r in the forming wire as shown in FIG.
The characteristics can be further improved by forming larger recesses with R and R> r. As a result of various studies, the width w and the depth h of the recessed portion
It was found that the curvature R or the C chamfer structure may be used as long as both w and h are within the range of 1 to 5 mm.

As described above, while the AN level can be reduced, the projected area of the electric wire can be reduced and the cross-sectional shape can be streamlined, so that the wind load can be reduced. Regarding the wind load, the conventional ACSR610, 116
0 mm ² and ACSR 610, 1160 mm with the configuration of FIG.
Fig. 9 shows the results of comparative measurement of ^two equivalent electric wires in terms of drag coefficient versus wind speed. The drag coefficient is an index for designing the aerodynamic characteristics of the electric wire, and the difference in effect between the present invention and the conventional electric wire can be clearly read from FIG. When the projected area is a problem, the equivalent average diameter can be obtained from the cross section that turns in the longitudinal direction and compared. As for snow accretion characteristics, b / a ≦ 1 / 1.2 also showed excellent snow accretion characteristics. On the other hand, according to the structure of the present invention, if the outermost layer of the element wire forming the ellipse is too thick or thin, the twisted structure becomes unstable, and there is a problem in the strength of the material. It became clear that a practical design is possible if a ≧ 1 / 1.7. In this sense, it can be said that the practical range of b / a in the present technology is the range of 1 / 1.2 to 1 / 1.7. In the above description, the cross-sectional shape of the electric wire of the present invention has been described as an ellipse, but it may be an ellipse close to an ellipse (substantially an ellipse). Further, although the present invention has been described mainly with respect to an overhead power transmission line, it is also effective for an overhead ground wire which is overhead-wired between steel towers like the overhead power transmission line. Especially in UHV transmission lines, due to the influence of the main line, low A
N conversion is desired, and as an example of application to an overhead ground wire, Fig. 1
The structure of the optical fiber composite overhead ground wire (OPGW) shown in FIG.

[0013]

By using the electric wire of the present invention for an overhead power transmission line and an overhead ground wire, noise accompanying corona discharge can be reduced, and wind noise and wind load can be reduced. It is possible to achieve the effect that snow does not easily arrive.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first example of an electric wire of the invention.

FIG. 2 is a sectional view showing a second example of the electric wire of the invention.

FIG. 3 is a cross-sectional view showing a third example of the electric wire of the invention.

FIG. 4 is a cross-sectional view showing an example of an elliptic wire.

5A and 5B are cross-sectional views of the electric wire having the configuration shown in FIG. 4, and FIG. 5B is a cross-sectional view of the electric wire having the configuration shown in FIG.

6 is a cross-sectional view showing an improved example of the electric wire having the configuration of FIG.

FIG. 7 is a cross-sectional view showing a first example of a conventional electric wire.

FIG. 8 is a sectional view showing a second example of a conventional electric wire.

FIG. 9 is a diagram showing the relationship between drag coefficient and wind speed for the present invention and a conventional electric wire.

FIG. 10 is a cross-sectional view showing an example of the electric wire of the present invention applied to an overhead ground wire.

[Explanation of symbols]

 1 steel core 2 circular element wire 3 non-circular element wire 4 circular element wire forming the inner layer 5 non-circular element wire forming the inner layer 6 circular element wire forming the outermost layer 7 non-circular element wire forming the outermost layer 8 water drop 9 Optical fiber unit 10 Steel wire 11 Aluminum coating

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[Procedure amendment]

[Submission date] June 10, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

[Figure 3]

Front page continuation (72) Inventor Nobuaki Suga 4-10-1, Kawajiri-cho, Hitachi, Hitachi, Ibaraki Hitachi Cable Ltd. Toyoura Plant (72) Inventor Hiroaki Ito 4-10-1, Kawajiri-cho, Hitachi, Ibaraki Hitachi Electric Cable Co., Ltd. Toyoura Plant (72) Inventor Narumi Iwama 5-1-1 Hidakacho, Hitachi City, Ibaraki Hitachi Cable Electric Power Co., Ltd.

Claims (7)

[Claims] 1. An elliptic cross-section comprising an inner layer having a circular cross section formed by twisting strands around a steel core and forming a concentric circle, and an outermost layer formed by twisting strands of different sizes in contact with the inner layer. Alternatively, in a substantially elliptical overhead wire, the outermost strands are arranged symmetrically with respect to the major axis, and the major axis passes between the paired maximum strands. Overhead electric wire. 2. The wire is made of aluminum or aluminum alloy,
The overhead wire according to claim 1, wherein a part or all of the wires are circular wires. 3. The wire is made of aluminum or aluminum alloy,
The overhead wire according to claim 1, wherein a part or all of the wire is a non-circular molded wire. 4. A major axis (a) and a minor axis (b) in a sectional shape.
The overhead wire according to any one of claims 1 to 3, characterized in that the ratio (b / a) thereof to the range (1) is in the range of 1 / 1.2 to 1 / 1.8. 5. An electric wire having a major axis larger than the outer diameter of an electric wire having a circular cross section and having an equivalent average diameter in the longitudinal direction is an outer diameter of the electric wire having a circular cross section when the electric wire having a circular cross section has a substantially same cross sectional area. The overhead wire according to any one of claims 1 to 4, wherein the overhead wire is configured to be substantially the same as or smaller than the above. 6. The structure according to claim 3 or 4, wherein the equivalent average diameter in the longitudinal direction is configured to be substantially the same as or smaller than the outer diameter of an electric wire made of a non-circular molded wire and having a circular cross section. Overhead electric wire. 7. A structure in which the major axis is substantially the same as the outer diameter of an electric wire made of a circular element and having a circular cross section, and the conductor cross sectional area is equal to or smaller than that of the electric wire having the circular cross section. The overhead electric wire according to any one of claims 1 to 4.