JPH10125137A - Overhead transmission line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To drain water penetrated between strands on the inside of a segment type stranded layer formed by twisting segment type strands to prevent the generation of corona noise. SOLUTION: A segment type stranded layer formed by twisting segment type strands is used. When the length of the whole or part of the adjacent contact part of the segment type strands 3a having the same thickness constituting the segment type stranded layer is represented by L and the maximum thickness in the diameter direction of the segment type strand is represented by D, the relation of L and D is specified as 0<L/D<=0.4 to decrease capillary action of the adjacent contact part of the segment type strands. Rainwater or other water penetrated into the inside of the segment type strand layer is quickly drained to the outside to prevent the generation of corona noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overhead transmission line capable of suppressing corona noise.

[0002]

2. Description of the Related Art An overhead power transmission line has a structure in which a large number of round-shaped strands are twisted, and a structure in which a round-shaped strand is twisted and a segment-shaped strand is twisted around its periphery. And others.

[0003] The above overhead transmission line has a problem that when exposed to rain or the like and rainwater adheres to the surface, corona is generated from the rainwater or the like and corona noise is generated.

[0004]

As a result of examining the corona noise of electric wires of various structures, the corona noise is obtained by twisting a segment type element wire rather than an overhead transmission line in which only a round cross-section element wire is twisted. It became clear that an overhead transmission line having at least one segment-type strand twisted layer is more likely to generate.

[0005] After various examinations of the reason, it has been found that an overhead transmission line in which a large number of round-shaped strands are stranded alone has water that has penetrated into the overhead transmission line passing between the round-shaped strands. The overhead power transmission line having at least one segment-type strand twisted layer obtained by twisting the segment-type strands while being easily discharged to the outside is located inside the segment-type strand twisted layer. Water that has entered between the strands is difficult to drain,
For this reason, water that has entered between the strands inside the segmented strand is gradually flowing out to the surface of the segmented strand, so that rainwater adheres to the surface of the segmented strand for a long time. Therefore, it has been clarified that corona noise is easily generated.

[0006] Among the overhead transmission lines in which segment-type strands are twisted, an overhead transmission line having a twisted layer formed by twisting a thick segment-type strand between thin segment-type strands in the outermost layer is particularly preferred. (Called low-noise wires) were found to be prone to corona noise. Thick segment-type wires in this overhead transmission line are provided to prevent wind noise, but the thick segment-type wires protrude from the surface of the overhead transmission line in a spiral shape. If rainwater adheres to the protruding thick segment wire, corona noise is likely to be generated. Generally, rainwater wraps below an overhead power transmission line and generates raindrops at the tip of a thick segment wire under the electric wire, so that corona noise is more likely to be generated.

[0007]

SUMMARY OF THE INVENTION The present invention has been made on the basis of the above-described examination results, and provides an overhead transmission line capable of suppressing corona noise, and has the following configuration.

[0008] That is, an overhead transmission line according to the present invention is an overhead transmission line comprising a segment-type strand twisted layer formed by twisting segment-type strands and having an outermost layer surface subjected to a hydrophilic treatment. The length L of all or a part of the adjacent contact portions of the segment type strands of the same thickness that constitute the strand twisted layer is defined as D, and the maximum radial thickness of the segment type strand is D. 0 <L / D ≦
0.4.

As described above, the length L of at least a portion of the adjacent contact portions of the adjacent contact portions of the segment type strands of the same thickness that constitute the segment type strand twisted layer is set to When the maximum thickness in the radial direction of D is D, 0 <
By setting L / D ≦ 0.4, the length of the adjacent contact portion between the adjacent segment-type strands can be shortened. As described above, when the length of the adjacent contact portion between the adjacent segment-type wires is shortened, the capillary force of the adjacent contact portion between the adjacent segment-type wires can be reduced. For this reason, rainwater or the like that has entered the inside of the segment type strand twisted layer is immediately drained to the outside. Further, since the surface of the outermost layer wire is subjected to a hydrophilic treatment, water droplets are less likely to be formed on the outermost layer wire surface, so that corona noise can be further reduced.

The reason why the drainage is promoted by shortening the length of the adjacent contact portion of the segment type strand as described above will be discussed in more detail with reference to FIGS. FIG.
FIG. 3 schematically shows a behavior of water 9 invading a gap 8 inside an overhead power transmission line in which a segment type element wire 3 is twisted to an outermost layer, which is observed from a cross-sectional direction using a videoscope.

When an overhead transmission line in which the segment type strands 3 are twisted in the outermost layer is exposed in the rainfall test apparatus, water 9 intrudes into the internal gap 8 from the gap between the segment type strands 3 in the outermost layer. Then, the internal space 8 is filled with water 9.

Next, when the rainfall is stopped, the water 9 in the void 8 is
Flows out through gaps between the segment-shaped strands 3 to form water droplets 12. In the initial period of about 30 seconds, the dropping is repeated frequently, and after one minute, the dropping speed becomes gradually slower. As the water 9 in the gap 8 flows out and decreases, the water 9 in the gap 8 is drawn to the wall surface of the strand, and a bubble 10 is formed at the center. The water 9 in the gap 8 and the water droplets 12 that have flowed outward through the gap between the segment-shaped wires 3 are connected by the water that has entered the gap between the segment-shaped wires 3. As a result of the observation,
It has been found that one of the conditions under which the water droplet 12 drops is related to the length L of the adjacent contact portion of the segment-type strand 3.
That is, if the length L of the adjacent contact portion of the segment-shaped strand 3 is long, the capillary force at the position is large, and the water 9 and the water droplet 12 in the gap 8 are connected by a large capillary force. Will remain below the wire for a long time without dropping. On the other hand, if the length L of the adjacent contact portion of the segment type wire 3 is short, the capillary force at the position is weakened, and the connection between the water 9 and the water droplet 12 in the gap 8 is also weakened. In this case, the water droplet 12 is easily dropped.

Length L of adjacent contact portion of segment type wire 4
It is preferable that the length is shorter because the capillary force can be weakened. Therefore, the minimum of the length L of the adjacent contact portion of the segment type strand 3 is substantially zero. On the other hand, as a result of various experiments, assuming that the maximum thickness in the radial direction of the segment-type wire is D, the length L of the adjacent contact portion of the segment-type wire 4 is L = 0.4D. It has been found that the capillary force at the adjacent contact portion of the wire can be greatly reduced, so that water droplets can easily fall.

In general, an overhead power transmission line is charged, and the applied overhead transmission line generates a force to pull water droplets downward. For this reason, in combination with the weakening of the capillary force, the water droplets 12 are more likely to drop. A description will be given of a point that a force for pulling a water drop is generated on the overhead transmission line to which power is applied in this manner, using a water drop model in FIG. 9.

As the factors contributing to the deformation of the water droplet, the pressure due to the weight of the water droplet (P _h ), the pressure due to the surface tension of the water droplet (P _s ), the pressure of the water droplet when the power is applied, There is a pressure (P ₀ ) generated by the surface charge, and when these combined pressures are (P), the following relationship is obtained. P = P _h + P ₀ −P _s Equation (1)

In the equation (1), when P = 0 at each point on the surface of the water droplet 12, the water droplet 12 keeps a parallel state and stops, but when P> 0, the water droplet 12 flows according to this value. Becomes deformed.

Each of the pressures P _h , P ₀ , and P _s is defined as h ₀ , the height from the water surface to the surface of the segmented wire, Y as the coordinate in the radial direction of the droplet, and X as the vertical coordinate. , And the distance from the surface of the segment type strand to the tip of the water droplet is x, and the acceleration of gravity is g, the following equation is obtained. Here, D: density of water droplets, q: surface charge density, e ₀ : dielectric constant, T: surface tension of water, R _a . R _b : radius of curvature at the point x of the water droplet surface.

Next, the surface charge density q is determined. For the sake of simplicity, the shape of the water droplet is a spheroid, and the equal electric field E ₀ in the X-axis direction is used.
If there are water droplets inside, the surface charge density q can be obtained by the following equation.

[0019] Here, r ₀ is the radius of the water droplet.

Next, the equation (3) is changed to the equation P ₀ = q / 2 in the equation (2).
When P ₀ is obtained by substituting into e ₀ , Here, M = ┤1- (x / mr 0) 2 N 2 ├ 1/2 N = ┤1-1 / m 2 ├ 1/2 m: the radius ratio of the water droplets.

As is apparent from the above equation (4), the electric field E
_{As the} pressure increases, the pressure P ₀ generated by the surface charge of the water droplet increases.
Also increases. Since the pressure P ₀ becomes stronger toward the tip of the water droplet, the force to be pulled in the X-axis direction becomes larger than when no power is applied. Therefore, at the time of power application, the water droplet is pulled downward before the water droplet becomes large, and since the water droplet base is small, the water droplet is elongated and then separated and falls as a small water droplet.
As the electric field is further strengthened, P ₀ becomes stronger and the water droplets are also stretched longer and corona begins to emerge.

In a conventional overhead power transmission line with poor water drainage, water that has penetrated into the outer layer oozes into the outer layer so as to be sucked from between the segment-shaped wires, and remains as a large number of water drops below the outer periphery of the electric wire. It becomes a corona source. On the other hand, in the overhead transmission line according to the present invention, as described above, since the length of the adjacent contact portion of the segment-type strand 3 is short and the capillary force at the position is weak, the water droplet generated by the power application is pulled downward. Drainage is facilitated by force. Therefore, the overhead transmission line according to the present invention can effectively reduce corona noise.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows a case where the present invention is applied to an overhead transmission line called a low noise electric line. 1 is a core stranded wire made of a high-strength wire rod or the like obtained by plating or coating a steel wire, an invar wire, a carbon fiber, an alumina fiber, a polyimide fiber, or the like with aluminum or zinc or the like, and 2 is stranded on the core stranded wire 1 in two layers. The aluminum wire 3 having a round cross section is a segment type wire twisted around the outer circumference of the aluminum wire 2 having a round cross section. The segment type strand 3 is a thin segment type strand 3
a thick segment type element wire 3b is twisted between a, two thick segment type element wires 3b are used, and the two thick segment type element wires 3b are It is twisted in a state where the thin segment wire 3a is sandwiched.

After the above-mentioned thin segment wire 3a and thick segment wire 3b are twisted, the outer surface portion is subjected to a hydrophilic treatment by a sandblasting treatment, an alumite treatment or a boehmite treatment. .

The overhead transmission line according to the present invention is shown in FIG.
As shown in FIG. 2 and FIG. 2, the length L of the adjacent contact portion between all the thin segment wires 3a is 0 <L / D, where D is the maximum radial thickness of the segment wire. ≦ 0.
It is 4. When the length L of the adjacent contact portion between the thin segment wires 3a is selected to such a value, the capillary force at the adjacent contact portion of the segment wire can be greatly reduced, so that drainage is promoted. Can be done.
For example, if the maximum thickness A in the radial direction of the thin segment wire 3a is 4.9 mm, the length L of the adjacent contact portion is 1.9.
6 mm or less.

The length l of the adjacent contact portion between the thin segment wire 3a and the thick segment wire 3b is the maximum thickness B (see FIG. 1) of the thick segment wire 3b in the radial direction. (See). As described above, the length 1 of the adjacent contact portion between the thin segment wire 3a and the thick segment wire 3b is set to be less than half the maximum radial thickness B of the thick segment wire 3b. Then, drainage at the position can also be improved.

In the above embodiment, in order to reduce the length L of the adjacent contact portion between the thin segment wires 3a, the inner surface 3e of the segment wire is formed into a spherical shape having a radius R _2. I have. By reducing the value of the radius R _2, it is possible to shorten the length L of the adjacent contact portions of the segmented strands. The value of the radius R ₂ are as appropriately selected.

As described above, the inner surface 3 of the segment-type strand is
When e is formed into a spherical shape with a radius R ₂ , the inner surface 3 e of the segment-type element wire becomes convex and does not become concave unlike the related art (see the dotted line portion in FIG. 2), and water hardly accumulates on the inner surface 3 e. For this reason, there is an advantage that drainage can be promoted.

As described above, the overhead transmission line according to the present invention
Since the drainage is promoted and since the surface of the outermost layer strand is subjected to the hydrophilic treatment, the drained water does not form water droplets on the surface, the corona noise can be further reduced.

In the above-described embodiment, the length L of the adjacent contact portion between all the thin segmented wires 3a is L.
Where the length L of the adjacent contact part is shortened,
For example, every other or every two may be used.

FIG. 3 shows another embodiment of the present invention, which is different from the above-mentioned embodiment in that four thick segment-type strands 3b are used, and the thick wall shown in FIG. Thick segmented wire 3b at the target position with segmented wire 3b
Are arranged two more.

With such a configuration, the noise reduction effect can be improved even if the height of the thick segment type strand 3b is reduced as compared with the configuration shown in FIG. The height of the segment type strand 3b can be reduced. For this reason, there is an effect that the thick segment type element wire 3b is hardly damaged at the time of manufacturing the electric wire or the overhead wire.
The other points are the same as those of the above-described embodiment, and thus the same reference numerals are given and the description is omitted.

FIG. 4 shows still another embodiment of the present invention. The difference from the embodiment shown in FIG. 3 is that the recesses 5 are formed at both corners of the inner surface as the segment-type wires 3. It is the point that the thing was used. By increasing the size of the depression 5, the length L of the adjacent contact portion of the segment-type strand 3 can be increased.
Can be shortened to a predetermined length or less.

Further, in FIG. 4, the thick segment type strands 3b are twisted by directly contacting each other. in this case,
In the recess 5 alone, the length L of the adjacent contact portion of the thick segment wire 3b is 0 <L / D, where D is the maximum radial thickness of the thick segment wire 3b. If ≦ 0.4, a groove 6 having a predetermined depth may be provided on the upper surface of the adjacent contact portion of the thick segment wire 3b. The depth of the groove 6 is, for example, about 2 mm. In FIG. 4, the same reference numerals are given to the same portions as those in the above-described embodiments, and the description will be omitted.

In the above embodiment, the length L of the adjacent contact portion between all the thin segmented wires 3a is set to L.
And the length L of the adjacent contact portion between the thick segmented wires 3b is also shortened. However, the portion where the length L of the adjacent contact portion is shortened is a portion adjacent to the thick segmented wires 3b. Instead of being provided at the contact portion, it may be provided only at the adjacent contact portion between all the thin segmented wires 3a, or may be provided at, for example, every other or every two.

FIG. 5 shows another embodiment of the segment type strand 3 used in the present invention, in which dents 5 are formed at four corners. When the depressions 5 are also formed at the corners of the outer surface of the segment type strand 3 in this manner, rainwater will
And the rainwater can be easily dripped.

FIG. 6 shows still another embodiment of the present invention, in which each segment-type element wire 3 is formed such that a V-shaped groove 7 is formed at a contact portion adjacent to the segment-type element wire 3. It was done. By changing the depth of the V-shaped groove 7, the length L of the adjacent contact portion of the segment-shaped element wire 3 can be appropriately selected. By forming such a V-shaped groove 7, the length L of the adjacent contact portion of the segment-shaped element wire 3 can be greatly reduced. According to various experiments, it has been clarified that the angle θ of the V-shaped groove 7 is preferably set to about 3 ° to 15 ° from the viewpoint of promoting drainage.

FIG. 6 shows a radius of curvature R _{3 at} the upper outer corner of the thick segment wire 3b in the embodiment.
That there is a larger radius than the radius of curvature R ₄ of the upper inner corner, corona is prevented from occurring from the upper outer corners of the thick segmented strands 3b. In FIG. 6, the same portions as those of the above-described embodiments are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 7 shows a structure of the overhead transmission line shown in FIG. 3, in which a thin segment-type wire 3a having a maximum thickness in the radial direction of 5.2 mm is used. Using a conventional segment having a length of 2.4 mm (L / D = 0.46) and a thin segment type element wire 3a having a maximum thickness in the radial direction of 5.2 mm; The length of the adjacent contact portion of the wire 3 is 0.65 mm (L / D
= 0.125), 1.2 mm (L / D = 0.23), and 2 mm (L / D = 0.38) when the corona hum sound level (dB) was measured. That is, the potential gradient Gmax on the surface of the electric wire is set to 14 kV / cm, a fixed amount of water is injected under the same conditions, and the corona hum sound level and the elapsed time characteristics are compared.

As is apparent from FIG. 7, the corona hum sound level does not decrease with time because the conventional overhead transmission line has poor water drainage properties. At the same time, the corona hum sound level is reduced. This tendency is remarkable when the length of the adjacent contact portion of the segment type wire is short, and the length of the adjacent contact portion is 0.65 m.
In the case of m, it was confirmed that a difference of as much as 14 dB occurred after 3 minutes as compared with the conventional one.

In each of the above embodiments, the low-noise electric wire in which the outermost layer is provided with a segment-type strand twisted layer formed by twisting a thick segment-type strand between thin segment-type strands. Although the present invention has been described in the context of the present invention, the present invention relates to, for example, a case in which a segment-type strand twisted layer in which a segment-type strand is twisted around the outer periphery of a twisted layer in which a round cross-section strand is twisted is used. An overhead transmission line constructed by layering and further twisting a single-layered round wire around its outer circumference, or a segment-type wire twisted by twisting only segment-type wires with a constant height on the outermost layer The present invention can also be applied to an overhead transmission line having a joining layer, an overhead transmission line having a plurality of segmented strand twisted layers, and the like. When applied to an overhead transmission line provided with a plurality of segmented strands, the length of adjacent contact portions of all the segmented strands is set to 0. It is preferable to set the length to at least four times, but at least the length of the adjacent contact part of all or a part of the outermost segment-shaped wire is 0.4 mm of the maximum radial thickness of the segmented wire. By setting it to twice, the drainage speed can be increased as compared with the conventional one.

Further, the position and the number of the portions where the lengths of the adjacent contact portions of the segment type wires are reduced are not particularly limited, and they may be provided at all the adjacent contact portions of the segment type wire. It may be provided at one or a plurality of arbitrary positions in the segment-type strand twisted layer.

[0043]

As described above, the overhead transmission line according to the present invention has the segment-type wire twisted layer in which the segment-type wires are twisted and the outermost layer wire surface is subjected to a hydrophilic treatment. In the transmission line, the length L of all or a part of the adjacent contact portions of the segment type strands of the same thickness that constitute the segment type strand twisted layer is determined in the radial direction of the segment type strand. Where D is the maximum thickness of
Since L / D ≦ 0.4, it is possible to weaken the capillary force of the adjacent contact portion between the adjacent segment-type strands. For this reason, rainwater or the like that has entered the inside of the segment-type strand twisted layer can be quickly drained to the outside. Further, since the surface of the outermost element wire is subjected to a hydrophilic treatment, it is difficult for the discharged water to form water droplets on the surface, so that corona noise can be further reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an overhead transmission line according to the present invention.

FIG. 2 is an enlarged sectional view showing a main part of FIG.

FIG. 3 is a sectional view showing a main part of another embodiment of the present invention.

FIG. 4 is a cross-sectional view showing another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing another example of a segment-type strand used in the present invention.

FIG. 6 is a cross-sectional view showing another embodiment of the present invention.

FIG. 7 is a graph showing an experimental example of the present invention.

FIG. 8 is an explanatory diagram showing a state of water that has entered the inside of the electric wire.

FIG. 9 is an explanatory diagram showing a water drop model.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 core stranded wire 2 round aluminum cross-section wire 3 segment wire 3 a thin segment wire 3 b thick segment wire 5 depression 6 groove 7 V-shaped groove D thin segment wire Maximum thickness in the radial direction B Maximum thickness in the radial direction of the thick segment type element wire L Length of adjacent contact portion.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jun Kato 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Takashi Shinohara 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Ken Abe 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (1)

[Claims] 1. An overhead transmission line having a segment-type strand twisted layer obtained by twisting segment-type strands and having an outermost strand surface subjected to a hydrophilic treatment, constitutes the segment-type strand twisted layer. Assuming that the length L of all or some of the adjacent contact portions of the segment type strands having the same thickness is the maximum thickness D in the radial direction of the segment type strands, 0 <L / An overhead transmission line, wherein D ≦ 0.4.