JPH11313430A - Wind noise prevention device for electric wires - Google Patents

Abstract

(57) [Abstract] [Problem] To provide wind noise prevention measures for overhead power transmission lines having a small tower strength. Improve workability.
Reduce costs. Exhibits a stable wind noise prevention effect. A long wire 3 made of rubber or resin and having an insulative tension member built therein is spirally wound around a wire 1 under tension, and the wound wire 3 is fixed to a predetermined length. Is fixed to the electric wire 1 by the locking member 4 at every interval of.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wind noise prevention device for electric wires.

[0002]

2. Description of the Related Art In overhead power transmission lines, noise due to wind blowing on electric wires may be a problem. Conventionally, as a means for preventing wind noise from electric wires, a method of winding an aluminum alloy spiral rod around the electric wires to change the air flow is known (Japanese Patent Publication No. 53-14146,
JP-B-60-31170). The spiral rod used here is an aluminum alloy wire having a thickness of 3 to 8 mm formed in a spiral shape in advance, and its length is set to about 2.5 m so that a worker can manually wind the wire around the wire. . Spiral rod spiral pitch is 300 ~ 500
mm, and the inner diameter of the spiral is set to tighten the electric wire.

[0003] Since the spiral rod has a short fixed length as described above, when wind noise prevention measures are taken in a certain section, a number of spiral rods are wound around the electric wire in the section.

[0004]

However, the conventional wind noise prevention device has the following problems. Since the spiral rod is made of metal, if it is wrapped around an electric wire, the weight of the electric wire increases and a large load is applied to the tower, which is a support, resulting in insufficient strength of the tower and wind noise In many cases, preventive measures cannot be taken. Since a large number of spiral rods need to be manually wound around an unstable place, the workability is poor, and the installation work requires a great deal of labor and time. Spiral rods are made of an aluminum alloy, so that the material cost is high, and since they need to be formed in a spiral shape in advance, the processing cost is high and the price is high. When the vehicle is run on a spiral rod wound around an electric wire for a regular inspection with a spacecraft or the like, the end of the spiral rod is easily loosened, and the rework is very troublesome.

An object of the present invention is to provide an electric wire wind noise prevention device which solves the above problems.

[0006]

In order to achieve the above object, a wind noise prevention device for an electric wire according to the present invention is provided. A long wire made of rubber or resin is spirally wound around an electric wire under tension. The wound linear member is fixed to the electric wire by a locking member at predetermined intervals. Rubber or resin linear body used in the present invention,
It is preferable to incorporate an insulating tension member.

For the material of the linear body, synthetic rubber such as silicon rubber, ethylene propylene rubber, butyl rubber and acrylic rubber can be used in the case of rubber, and polyethylene, polyamide, fluorine resin and the like in the case of resin. can do. As the tension member incorporated in the linear body, a rope in which insulating fibers are twisted, a FRP (fiber reinforced plastic) wire, or the like can be used. The length of the linear body is not particularly limited in the case of a single conductor, but in the case of a multi-conductor power transmission line, since there is a spacer, it may be wound at a length of 20 to 50 m at every spacer attachment interval. Alternatively, the spacer may be temporarily removed and a longer linear body may be wound. Further, the interval at which the linear body is fixed to the electric wire by the locking member is preferably 以下 or less of the inter-phase distance of the transmission line, and more preferably, 1 to 2 m.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 and FIG.
An embodiment when applied to a conductor transmission line is shown. In the figure, reference numeral 1 denotes an electric wire (elementary conductor) constituting a four-conductor power transmission line, which is usually constituted by ACSR (steel core aluminum stranded wire), and its outer diameter is usually 22.4 to 52.8 mm. 2 is electric wire 1
These spacers are attached at intervals of about 20 to 50 m to prevent mutual contact by electromagnetic force or strong wind.

A wire 3 made of rubber or resin and having a built-in insulating tension member 3T as shown in FIG. 3 is spirally wound around the outer periphery of each wire 1 at a predetermined pitch. The winding of the linear body 3 is performed under tension. Since the tension member 3T is contained in the linear body 3, no excessive elongation occurs even when wound with tension.
The wire can be efficiently and tightly wound. As the tension member 3T, a rope or an FRP wire rod in which insulating fibers are twisted is used. When the linear member 3 is made of rubber and has no tension member,
It is convenient to wind with a tension such that an elongation of 10 to 30% occurs, since no loosening occurs after winding. When the linear body 3 is made of a resin having a small elongation and has no tension member, it is convenient to wind it while applying a tension of about 10 to 50 kgf, so that there is no loosening after winding.

The thickness of the linear body 3 is preferably 2 to 8 mm, and a thin (thick) linear body is used for a thin (thick) electric wire.
The helical pitch P of the linear body 1 may be 200 to 500 mm, but if the helical pitch is the same as the twist pitch of the electric wire, a gap between the outermost strand and the linear body is eliminated, so that gap discharge hardly occurs, and higher voltage transmission is performed. Suitable for electric wires.

The linear body 3 wound around the electric wire 1 is fixed to the electric wire 1 at predetermined intervals by a ring-shaped locking member 4. As the locking member 4, for example, one having the same structure as a known snow-resistant ring may be used. Of course, other structures can be used. Even if the linear body 3 is cut and hangs down,
The interval may be set so as not to cause a short circuit with the electric wire of another phase, for example, an interval equal to or less than １ ／ of the inter-phase distance of the transmission line. Although it depends on the voltage of the ultra-high voltage transmission line, if the transmission line is 275 kV,
The interval may be about 5 m. Further, since the linear body 3 itself is an insulating material, there is little concern that a short circuit accident may occur even if the linear body 3 is disconnected and hangs down, and it is safe. Further, the linear body 3 may be bonded to the electric wire 1 using an appropriate adhesive. In this case, if the adhesion is strong, the locking member 4 can be omitted.

As described above, the linear member 3 made of rubber or resin is used.
When the wire is wound around the electric wire 1, the weight increase of the electric wire is less than when the spiral rod made of an aluminum alloy is wound, so that it is possible to take measures against wind noise even on an overhead transmission line having a small tower strength. . In addition, since the long linear body 3 can be automatically wound by a winding machine that is wound around a bobbin and runs on the electric wire, workability is greatly improved. Further, since the linear body 3 is made of rubber or resin and has a low material cost and does not need to be formed in a spiral shape, the cost can be significantly reduced compared to a spiral rod.

Further, since the long linear body 3 is used, the end of the linear body 3 is located within the span significantly less than in the case of the spiral rod, and the problem of loosening of the end is reduced. Dramatically reduced. Also, the wire 3 is tensioned to
And is fixed at appropriate intervals by the locking member 4, so that it does not float or shift from the surface of the electric wire, and a stable wind noise prevention effect can be exhibited. Further, since the linear body 3 is softer than the electric wire 1, there is no possibility of damaging the electric wire 1 at the time of winding and does not impair the corona characteristics of the electric wire.

As the linear member 3, a solid linear member having a circular cross section is usually used, but a linear member as shown in FIGS. 4A to 4D can also be used. The linear member 3 of (A) is a hollow tubular member, and such a structure is preferable in order to further reduce the weight. The linear body 3 in (B) has a thickness periodically changed in the longitudinal direction. When the wire 3 is wound so that the thin portion is located on the side surface (windward, leeward) of the electric wire in association with the helical pitch, compared to the case of winding a wire having a uniform cross section, Lower wind pressure and lighter weight can be achieved. Since a linear body that falls within the range of the diameter of the electric wire when viewed from the side is not so effective in preventing wind noise, the linear body that falls within this range may be thin.

The linear member 3 shown in FIG. 1C is a plate or a band, and is used when it is desired to improve the corona noise characteristics even if the effect of preventing wind noise is somewhat sacrificed. Although the cross section is rectangular in (C), if the cross section is formed in an arc shape in accordance with the outer peripheral surface of the electric wire, both side edges do not rise from the outer peripheral surface of the electric wire,
This is convenient for gap discharge prevention and the like. In the linear body 3 of (D), the side in contact with the electric wire is a semiconductor 5 and the outer side is an insulator 6. Such 2
When the linear body 3 having a layer structure is used, it is possible to more effectively prevent a gap discharge from occurring between the electric wire and the electric wire.

FIG. 5 is a view for explaining that the wind resistance decreases when the wire 3 is wound around the electric wire 1.
(A) is a case where wind V is blown from the lateral direction to the electric wire 1 having a circular cross-section where the linear body is not wound. In this case, the separation point θ of the turbulent boundary layer becomes 70 ° to 80 °. As a result, the wake area 7 on the leeward side is widened and the wind pressure resistance is increased. On the other hand, (B) shows a case where wind V blows from a lateral direction to the electric wire 1 having a circular cross section around which the linear body 3 is wound. In this case, the turbulent boundary layer is disturbed, and the turbulence once separated is obtained. Since the flow boundary layer is attached again behind the linear body 3 and the final separation point θ is 110 to 120 °, the wake region 7 is greatly reduced, and the wind pressure resistance is significantly reduced.

In the above embodiment, the case where the present invention is applied to an overhead power transmission line has been described. However, the present invention is not limited to this, and the insulating coating is applied like a distribution line and the surface is smooth. The same can be applied to a simple electric wire. Since the distribution line has a smooth surface and a cross section that is close to a perfect circle, wind noise tends to occur and the wind pressure load tends to be large, and the effect of the present invention is more remarkable.

[0018]

FIG. 6 shows an ACSR 330 mm ² (outer diameter 25.3).
mm) and a wire with a diameter of 3.0 mm to
The result of measuring the wind noise level in a wind tunnel test at a wind speed of 20 m / sec when one 4.5 mm linear body is wound at a spiral pitch of 300 mm (the present invention) is shown. The effective wire length used for the measurement is 1 m, and the distance from the wire to the microphone is 1 m.

As can be seen from FIG. 6, the predominant frequency is around 170 Hz in the electric wire without taking measures against wind noise, and the noise level is 60 dB. However, when the present invention is applied, the noise level is drastically reduced to 37 dB. Then, it will be at a level that is hardly a problem. There is no particular difference in the wind noise reduction effect due to the difference in the thickness of the linear body, suggesting that the target noise level can be achieved with a thickness of less than 3 mm if the target level is 45 dB. .

FIG. 7 shows an ACSR 810 mm ² (outer diameter 38.4).
mm) and a rubber wire 2 with an outer diameter of 2.5 mm
The results of measuring the wind pressure resistance coefficient (drag coefficient) Cd when the books are wound at 180 ° intervals at a spiral pitch of 350 mm (the present invention) are shown. The wind pressure resistance of the electric wire becomes a problem during a strong wind such as a typhoon, and the design of transmission lines in Japan adopts a wind pressure load at a wind speed of 40 m / sec. The wind pressure load Pw is expressed by the following equation.

[0021]

Pw = １ ／ · Cd · D · V ² · ρ (k
gf / m ² )

That is, the wind pressure load Pw is proportional to the wind pressure resistance coefficient Cd, the wire outer diameter D, and the air density ρ.
It increases in proportion to the power. Therefore, it is desirable that the wind pressure resistance coefficient Cd be as small as possible in a high wind speed region. As can be seen from FIG. 7, when compared at a wind speed of 40 m, Cd is 0.98 for an electric wire that is not wound with a linear body, whereas Cd is 0.79 for an electric wire that is wound with a linear body.
9 / 0.98 = 0.8, that is, Cd can be reduced to 80%.

In the United States and the like, the power transmission line is often damaged by a hurricane called a hurricane at a wind speed of 60 to 80 m / sec. Even in such a strong wind region, the electric wire to which the device of the present invention is attached has a stable Cd. Therefore, damage can be minimized. For example, wind speed 80
At m / s, Cd can be reduced by 15%.

FIG. 8 shows an ACSR 330 mm ² (outer diameter 25.3).
mm) and a wire with a diameter of 3.0 mm to
This is the result of measuring the corona hum sound characteristics when a 4.5 mm linear body is wound at a spiral pitch of 300 mm (the present invention). The corona hum is a noise with a frequency twice the power frequency, similar to a transformer noise called boon,
Due to the extremely low frequency, there is little attenuation, and even when the windows are closed, it can be annoying when light rain occurs. According to FIG.
It can be seen that the thinner the linear body, the lower the noise level and the better the corona hum sound characteristics.

[0025]

As described above, according to the present invention, a wire made of rubber or resin is wrapped around an electric wire, so that an increase in weight of the wire after wrapping is small and the overhead strength of the tower is not limited. Wind noise prevention measures can also be applied to electric wires. In addition, since a long linear body is used, the construction can be efficiently performed using a lashing machine or the like, and the workability is greatly improved. In particular, if a linear body containing a tension member is used, excessive elongation does not occur even when wound with tension,
The wire can be efficiently and tightly wound. In addition, since the linear body is wound around the electric wire under tension and fixed at appropriate intervals by a locking member, the linear body can be prevented from loosening and floating, and the linear body can be loosened and lifted. In addition to eliminating corona noise, a stable wind noise prevention effect can be exhibited. In addition, since a long linear body is wound around an electric wire, a step of forming a spiral in advance like a conventional spiral rod can be omitted, and a significant cost reduction can be achieved in combination with the overall weight reduction.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a wind noise prevention device for an electric wire according to the present invention.

FIG. 2 is an enlarged view of a main part of the embodiment of FIG.

FIG. 3 is a sectional view of a linear body used in the embodiment of FIG. 1;

FIGS. 4A to 4D are perspective views showing types of linear bodies that can be used in the present invention.

FIG. 5 (A) shows an electric wire on which a linear body is not wound.
(B) is a diagram for explaining wind pressure resistance when wind is blown on an electric wire around which a linear body is wound.

FIG. 6 is a graph showing measurement results of wind noise levels of an electric wire not wound around a linear body and an electric wire wound around a linear body.

FIG. 7 is a graph showing measurement results of a wind pressure resistance coefficient (drag coefficient).

FIG. 8 is a graph showing a measurement result of a corona hum sound level.

[Explanation of symbols]

 1: wire 2: spacer 3: linear body 3T: tension member 4: locking member

Claims (2)

[Claims] 1. An electric wire made of rubber or resin and having a length of at least 20 m.
Wind noise of an electric wire, wherein a wire having the above-mentioned length is spirally wound under tension, and the wound wire is fixed to an electric wire by a locking member at predetermined intervals. Prevention device. 2. The wind noise prevention device for an electric wire according to claim 1, wherein the wire has a built-in insulating tension member.