JPS5838884B2 - overhead power lines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an overhead power transmission line in which a separate wire is wound around the wire in order to prevent wind noise.

It is known that the noise generated by overhead power transmission lines when exposed to wind pressure is due to the vortices generated behind the wires having a regular periodicity due to the unusual cross-sectional shape of the wires.

Therefore, in order to eliminate this noise, it is sufficient to change the cross-sectional shape of the wire to disturb the regular periodicity of the vortex.
One effective means for this purpose is to wrap a separate strand 2 around the outer periphery of the electric wire 1, as shown in FIG.

However, in this case, from an external perspective, it is the same as the formation of a protrusion 2 on the outer periphery of the electric wire 1, so the corona caused by this protrusion must be taken into consideration for overhead power transmission lines, which are becoming increasingly high-voltage. Especially in rainy weather, this corona noise cannot be ignored.

The present invention has been made in view of the above points.

That is, an object of the present invention is to provide an overhead power transmission line that can effectively reduce the corona noise as well as prevent wind noise, and its gist is to group a plurality of unit wires. This is because the wires in the group are brought into close contact with each other, and fine irregularities are formed on the outer surface of the wires.

The number of strands constituting one group is not particularly limited, but is preferably 2 to 3.

From the standpoint of alleviating the electric field near the wire, the more the better.
If the number of strands is increased too much, it will cause problems in terms of preventing wind noise, so in the end, it is preferable that the number of wires be 2 to 3 to suitably satisfy both electric field relaxation and wind noise prevention. .

Next, an embodiment of the electric wire of the present invention will be described with reference to FIG. 3 of the accompanying drawings, but it is not to be said that the present invention is to be interpreted as being limited to this embodiment.

Now, 10 is steel core aluminum stranded wire (hereinafter AC8R)
It is abbreviated as.

), 20 are aluminum wires (aluminum spiral rods) wrapped around the AC3R100, respectively.

As shown in the figure, the strands 20 and 20 are grouped in pairs, and the strands in each group are brought into close contact with each other.

Further, each of the wires 20, 20 has been treated with an alkaline solution in advance, so that the surface thereof is appropriately roughened to form fine irregularities.

For example, the surface treatment is performed by applying N of about 0.1 to 1 normal to the wire 20.
This is done by immersing in an aOH solution for about 15 minutes to 1 hour and then air drying.

Next, an explanation will be given based on the results of a demonstration test related to the present invention.

810mm2 ACSR (surface NaOH treatment) as electric wire
An aluminum alloy wire of 6rIrJnφ was wound around this, and the intensity of corona noise actually generated was measured.

The samples are as follows. (No) 810rrrm2
AC8R only (no strand winding) (a) Diagonal winding of two strands whose surface has been made finely uneven with NaOH (b) Closely winding of the same two strands as above (...) Diagonal winding of the same two strands of strands as above ( d) Wrap the same 3 strands in close contact (A') Wind 2 strands of wire without surface treatment diagonally (A')
) Same as above, two wires are tightly wound (...') Same as above, two wires are wound diagonally (2l)
Three strips of the same as above were wrapped closely together and each of these samples was sprinkled with water equivalent to a rainfall of 30 myn/h, and then watered with water of 11,160 Kv with the surface wet.
A microphone was set at a distance of 35 points from the wire, and the intensity of corona noise generated from each sample was measured.

FIG. 5 is a diagram in which the shape of each sample is plotted on the horizontal axis, and the no-corona noise level is plotted for each sample.

In FIG. 5, each of the samples is shown with a symbol and a cross-sectional shape, and the corona noise level of each sample is plotted above.

As can be clearly seen from FIG. 5, (1) When the surface of the strand is not subjected to fine unevenness treatment, the corona noise is higher than when the strand is not wound (no winding), no matter how the strand is wound.

(I′) (mouth′) (ha′)j? Even if the surface roughness treatment is performed, if the strands are not in close contact and are located diagonally, the corona noise will still be higher than that without winding the strands.

(a) (3) If the surface is treated with fine irregularities and tightly wrapped, corona noise will be significantly reduced.

((b) (...) and (d)) This is why the corona noise is significantly reduced in the case of the sample (b) (...) button and (d) configurations according to the present invention. By winding the strands in groups, the cross-sectional shape of the strands can be flattened as a whole compared to when the strands are individually wound one by one, and the electric field in that area is more effectively relaxed. This is thought to be because by forming fine irregularities on the upper wire, the water droplet on the wire becomes flat due to capillary action, and the electric field of the water droplet itself is also relaxed.

As described above, the overhead power transmission line of the present invention can effectively reduce corona noise as well as prevent wind noise, and its practical value is extremely large.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of a conventional overhead power transmission line, and Figure 2 is its A-
FIG. 3 is a diagram illustrating an embodiment of the overhead power transmission line of the present invention, and FIG. 4 is a sectional view of the section B-B' thereof. FIG. 5 is a diagram showing the results of a verification test. 10: AC8R, 20... Aluminum wire.

Claims (1)

[Claims] 1. For low-noise electric wires made by winding strands around the outer periphery of the wire, the strands to be wound are made up of a plurality of unit strands with fine irregularities formed on the surface, which are brought into close contact with each other. A low-corona, low-noise electric wire that is characterized by: