JPH08306234A - Low noise overhead power transmission line - Google Patents

Abstract

PURPOSE: To suppress a corona noise immediately after a rain fall in an early stage by forming grooves on the outer circumference in the lengthy direction of a thick wire of an overhead power transmission line having level difference in the outermost layer. CONSTITUTION: An overhead power transmission line is formed in such a way that an aluminum stranded conductor comprising aluminum element wires 2 is intertwisted on a stranded conductor comprising a plurality of steel wires 1, then almost fan-shaped wires 3, 4 having different thickness in the diameter direction of a power transmission line are intertwisted on the aluminum stranded conductor. A plurality of grooves 6 are formed on the outer circumference 5 of the wire 4 thicker than the wire 3. The dimension of the groove 6 is specified as w>nb>0, e>=1, b=0.1-2mm, w=3-9mm, d=0.1-2mm when the width of the wire is (w), the width of the groove is (b), the depth of the groove is (d), and the number of the grooves is (n). Even if water drops are attached, the water drops are diffused in the lengthy direction of the wire by the grooves 6, hardly formed in the projection shape, and as a result, the level of corona noise is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overhead power transmission line for reducing corona noise immediately after rainfall as early as possible.

[0002]

2. Description of the Related Art For example, an overhead power transmission line shown in FIG. 5 has an aluminum wire 2 on the outer periphery of a stranded wire formed by twisting seven steel wires 21.
2 is twisted, and the outer circumference thereof has a difference in the so-called thickness direction in the radial direction of the overhead power transmission line, which is an assembly in which strands 23 and 24 having a substantially fan-shaped cross section are twisted together. According to the proposal, a step is provided in the outermost layer of the twisted wire due to the difference in height, and a wide groove 27 is provided as if the strand 23 'is sandwiched between the steps (Japanese Patent Publication No. 6-93327). Issue).

[0003]

In this overhead power transmission line, the remaining raindrops after the raindrops trapped in the groove 27 fall as waterdrops, and the waterdrops stay in the groove 27 due to the surface tension, so that the outer diameter of the electric wire is reduced. On the other hand, it is said that the influence of the shape of the convex portion can be mitigated and the corona noise can be reduced. However, as shown in FIG. 5, when water drops 28 adhere to the outer peripheral surface 25 of the strands 23 and 24 having steps, a so-called protrusion shape is formed, and when a voltage is applied to the overhead power transmission line, the water drops become a sharp shape. Therefore, since corona noise increases, further reduction of corona noise has been desired in a short time immediately after rainfall.

[0004]

The overhead power transmission line according to the present invention is an overhead power transmission line having a step in the outermost layer by providing a difference in the thickness direction of the wires forming the outermost layer. It is characterized in that a groove is formed on the outer peripheral surface in the longitudinal direction of a thick wire, and the cross section of the thick wire is substantially fan-shaped and A groove is formed on the outer peripheral surface. In this case, when the strand width is w, the groove width is b, the groove depth is d, and the number of grooves is n, w
>Nb> 0, and n ≧ 1 b = 0.1 to 2 mm w = 3 to 9 mm d = 0.1 to 2 mm, which is a low noise overhead power transmission line.

The groove width b and the groove depth d = 0.1 to 2 mm are set because the water draining property is deteriorated when the thickness exceeds 2 mm and the corona noise reducing effect is reduced, and the case where the width is less than 0.1 mm is the same. Because it is. Also, w is 3-9 mm is 3
If it is less than 9 mm, the stability of the strand during manufacturing the stranded wire is lacking, and if it exceeds 9 mm, the rigidity becomes strong and the bendability of the transmission line deteriorates. It suffices that the number n of the grooves is one or more, which is effective in reducing corona noise.

[0006]

In the present invention, as shown in FIG. 1, even if the water droplets 8 adhere to the outer peripheral surfaces 5 of the strands 3 and 4 having steps, the water droplets 8 are diffused by the groove 6 in the wire length direction. Therefore, even if the volume of the water droplet is the same as in the case of FIG. 5,
Since the surface area is large, even if an electric charge is added to the overhead power transmission line, the water droplet 8 is unlikely to have a projection shape, and as a result, the level of corona noise is reduced.

[0007]

EXAMPLE FIG. 1 shows a cross-sectional view of an overhead power transmission line, in which an aluminum stranded wire made of an aluminum element wire 2 is twisted around a stranded wire made of a plurality of steel element wires 1. Around the outer circumference surface of a wire 4 having a thickness larger than that of the substantially fan-shaped wire 3, a plurality of grooves are formed by appropriately twisting around the fan-shaped wire having different thicknesses in the diametrical direction. 6 is provided. The groove 6 has a width of 0.6 mm and a depth of 0.6 mm,
It has a U-shaped cross section in order to reduce the notch strength. A spray-type water injection experiment was conducted on a sample of an overhead power transmission line in which two or three grooves 6 were provided on the outer peripheral surface 5 in a state where the potential gradient was 14.5 kv / cm.

As a result of this experiment, changes in noise immediately after water injection are shown in FIG. 2 or FIG. From the results of this experiment, in the case of an overhead power transmission line in which a groove is provided in a thick strand, corona noise is random (Fig. 2) and hum (Fig. 3) within a short time as the number of grooves increases. It can be seen that it is decreasing. It should be noted that the random sound means noise at all frequencies, and the hum sound means noise at an integral multiple of the commercial frequency in the overhead power transmission line.

FIG. 4 shows another embodiment, in which an aluminum stranded wire made of an aluminum element wire 12 is twisted around a stranded wire made of a plurality of steel element wires 11, and further the outer circumference thereof. In addition, substantially fan-shaped element wires having different thicknesses in the diametrical direction of the overhead transmission line are appropriately twisted, and a plurality of grooves 16 are formed on the outer peripheral surface 15 of the element wire 14 having a thickness larger than that of the substantially fan-shaped element wire 13. A plurality of strands 14 of a large thickness that are provided are arranged so as to be adjacent to each other. The dimensions and shape of the groove 16 are the same as those of the embodiment of FIG. 1, and when the number of adjacent thick wires 14 is preferably two to five, water droplets 18 are dispersed to prevent corona noise. More preferable.

[0010]

As described above, according to the present invention, corona noise immediately after rainfall can be reduced at an early stage.
It can be said that the adaptation to the super high voltage overhead transmission line where corona noise is a problem is extremely useful.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an overhead power transmission line showing the configuration of the present embodiment and a schematic state of water droplets attached to the overhead power transmission line.

FIG. 2 shows a change in random sound in the corona noise of this embodiment.

FIG. 3 is a graph showing a change in hum sound in the corona noise of the present embodiment.

FIG. 4 is a cross-sectional view showing an overhead power transmission line showing another configuration of the present embodiment and a schematic state of water droplets attached to the overhead power transmission line.

FIG. 5 is a cross-sectional view showing a general state of a conventional overhead power transmission line and water droplets attached thereto.

[Explanation of symbols]

 1.11.21: Steel element wire 2.12.22: Aluminum element wire 3.13.23.3'23 ': Element wire 4.14.24: Element wire 5.15.25: Outer peripheral surface 6. 16: Groove 7.27: Wide groove 8.18.28: Water drop

Claims (7)

[Claims] 1. An overhead transmission line having a step in the outermost layer by providing a plurality of strands having a large thickness among the strands forming the outermost layer and providing a difference in the thickness direction, A low-noise overhead power transmission line, characterized in that a groove is formed on the outer circumferential surface of a large strand in the longitudinal direction. 2. The low noise overhead power transmission line according to claim 1, wherein the cross section of the strand having at least a large thickness is substantially fan-shaped. 3. When the strand width is w, the groove width is b, the groove depth is d, and the number of grooves is n, w>nb> 0 and n ≧ 1 b = 0.1 to 2 mm w = 3-9 mm d = 0.1-2 mm The low noise overhead power transmission line according to claim 1 or 2. 4. The low noise overhead power transmission line according to claim 3, wherein the number of grooves formed on the outer peripheral surface of the thick wire is preferably two or more. 5. The low noise overhead power transmission line according to claim 1, wherein one thin wire is interposed between two thick wires. . 6. The low noise overhead power transmission line according to claim 1, wherein a plurality of strands having a large thickness are arranged adjacent to each other in a distributed manner. 7. The low noise overhead power transmission line according to claim 6, wherein the number of adjacent thick wires is 2 to 5.