JPH0697572B2 - Low AN type low noise electric wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention reduces wind noise and wind pressure by selecting a specific shape for the outer circumference of an electric wire without winding a separate member such as a spiral rod. Not only that, but also AN (Audible Nois) caused by corona generated by raindrops during rainfall.
e, same hereafter) for wind noise AN countermeasure cooperative type electric wire that can be greatly reduced.

[Prior Art] As shown in FIG. 14, the outermost stranded wire layer of an electric wire is composed of two types of wires 1, 1 and 2, 2 which are substantially fan-shaped in cross section and have different wall thicknesses in the radial direction of the wire. The applicant has already proposed a low wind noise electric wire 10 in which smooth spiral stepped surfaces 10a and 10b are formed on the outermost circumference of the electric wire. (JP-A-59-96603) As shown in FIG. 15, the central angle of the large-diameter step portion 10a is θ, the outer diameter of the large-diameter step surface 10a is D ₁ , and the outer diameter of the small-diameter step portion 10b is D ₂ , the height difference is h, and the pitch of the large-diameter step portion 10a is P
When each of the above conditions is specified, the wind generated from the wire can be generated by selecting a specific wire outer peripheral shape without winding another member such as the spiral rod that has been widely adopted in the past. It reduces noise.

The wind noise prevention effect of the above-mentioned proposed low wind noise electric wire is remarkable when it is wired as a single conductor, but it is not always possible to obtain the expected effect when it is wired as a multiconductor. It became clear gradually.

The effect is reduced in the case of multiple conductors while being very effective in the case of single conductors, because the conductor arrangement peculiar to multiple conductors is involved. That is, in the case of a multi-conductor transmission line, the conductors are arranged in parallel in the lateral direction as shown in FIG. 13, and when the wind blows as shown by the white arrow in the figure, the upstream conductor 10 ₁ and the downstream conductor 10 ₁ An arrangement relationship of 10 ₂ occurs.

When wind blows on the multi-conductor transmission line in which the conductors 10 ₁ and 10 ₂ are arranged in parallel with a distance L as shown in FIG. 13, a turbulent flow region is generated in the air flow on the leeward side of the upstream conductor 10 _1. The air in the turbulent flow region is delayed in the backward movement due to turbulent flow, whereas the air outside the turbulent flow region flows smoothly at the original constant velocity of the wind, so the separation shear of the air is generated at the interface. A layer S results.

The peel shear layer S is intended to make the culprit of wind noise in the multi-conductor, caused peculiar air vibrations by abuts this peeling shear layer S on the downstream side conductor 10 ₂ separated by spacing L, high wind noise Cause to occur.

Therefore, the applicant also previously proposed a low-noise electric wire that can effectively reduce wind noise even when configured as such a multi-conductor transmission line. (Japanese Patent Application No. 1-79417) As shown in FIG. 12, the central angle formed by the real surfaces A to A ′ of the large diameter step portion is θe, and the large diameter step surface is
The height difference between 10a and the small-diameter step surface 10b is h, and the arc center O, O'on a virtual line connecting the edges A, A'of the real surface of the large-diameter step portion and the center of the electric wire has an end of the real surface. 20 ° ≤ θe ≤ 60 ° 2 ≤ h ≤ 3 (mm) 1.5 ≤ R ≤ 3 (mm), where R is the radius of curvature of the end circular arc surface formed on both side edges of the step portion with a diameter larger than the edge. It is configured to be.

When θe, h and R are set so as to fall within the specified range, it is possible to remarkably reduce the generation of wind noise due to the separation shear layer of the air flow that is peculiar to the multiconductor.

[Problems to be Solved by the Invention] With each of the above proposals, it becomes possible to sufficiently suppress noise generated by wind pressure in electric wires not only in single-conductor transmission lines but also in multi-conductor transmission lines. We were able to find a solution to the environmental problems caused by the wind noise.

However, it has been pointed out that another problem lurks here as the transmission lines are becoming extremely high in voltage.

This is because water droplets attached to the lower surface of the transmission line especially during rainfall caused the potential gradient of the water droplets attached in a protruding state to rise, causing the problem of corona noise or AN. is there.

If there is a spiral step on the outer surface of the wire,
The stepped portion collects rainwater and guides it toward the lower surface to flow down, which facilitates the growth of raindrop grains on the large-diameter stepped surface that is on the lower side, and the above-mentioned AN tends to occur due to the large-sized droplets. Become.

The occurrence of such an AN is a problem that is fatally accompanied by an increase in the transmission voltage of an overhead power transmission line, and even an ordinary electric wire is not without such a problem.

However, a low-noise electric wire basically reduces noise by forming a protrusion or a step on the outer circumference of the electric wire,
It is undeniable that the AN is likely to occur. This is also the case with the method of winding the spiral rod around the outer circumference of the wire, but the applicant has already proposed a countermeasure against AN generation by this spiral rod and has reached a temporary solution. (Patent No. 1235450) However, as shown in FIGS. 10 (A) to 10 (C), respectively, there are proposals for reducing wind noise or making it harder to snow by a method other than spiral rod winding. Many. That is, FIG. 10 (A) is an example of a preset proposal made by the applicant described above, and FIG. 10 (B) is a round wire 3, 3 and a deformed wire 4 on the outer layer.
(C) is an example in which the fan-shaped element wires 5, 5 are twisted and a projection 6 is formed in a part thereof.

FIG. 11 shows an electric wire having the shape shown in FIGS. 10 (A) to (C).
It is a plot diagram that plots the results of the AN value comparison with the conventional wire, which was carried out in the corona cage using 10,10 ′, 10 ″.
Equivalent to ACSR 810 mm ² , the central angle θ of the large-diameter step portion of the electric wire 10 in (A) is 90 °, the height difference h is 2.5 mm, and the electric wire 10 'in (B) is
2.5mm, width 5mm, radius of curvature 5m
m, the height of the protrusion 6 of the electric wire 10 ″ of (C) 1.5 mm, width 1.
It is 5 mm.

The wire 10 proposed by the applicant has a slightly smaller increase in the AN value than the other wires 10 ′, 10 ″, but it can be seen that the AN value is still increased by about 5 dB compared with the conventional wire. .

In the case of the spiral rod winding described above, this AN value problem has been solved, but complicated winding work is required, and special adjustment of the tower reinforcement and slackness is required due to increased wind pressure load and weight. There are also many incidental works.

In view of the above situation, the object of the present invention is not only to reduce the wind noise and wind pressure by simply selecting the shape of the electric wire, but also due to the corona generated by water droplets during rainfall. It is intended to provide a new low AN type low noise electric wire that can greatly reduce AN.

[Means for Solving the Problems] In the present invention, the outermost stranded wire layer of a stranded wire is composed of a thick-walled element wire and a thin-walled element wire having a substantially fan-shaped cross section, and the twisted wire outer peripheral surface is formed by the difference in the thickness. In an electric wire in which the step surface is formed in a spiral shape, an interposing wire having a height lower than that of the thick-walled wire is arranged between the thick-walled wires forming the large-diameter stepped surface, and the large-diameter stepped portion is almost A recess having a width is formed at the center at the bottom, the central angle formed by the side surface of the recess with respect to the center of the wire is θo, the central angle formed by the actual surface of the large diameter step surface is θe, and the bottom of the recess is inscribed When the distance between the intersections of the virtual concentric circles with the electric wires and the side surfaces of the thick-walled wires on both sides is δ, and the depth of the concave portion represented by the difference in radial direction between the bottom virtual circle and the large-diameter step circle is ho , 0.2 ≤ θo / θe ≤ 0.7 ho ≥ 1 (mm) δ ≥ 2 (mm). In order to apply to a power transmission line as well, by weighting the above conditions, the height difference between the large diameter step surface and the small diameter step surface is set to h, and a virtual line connecting the edge of the actual surface of the large diameter step portion and the center of the electric wire When the radius of curvature of the end arc surface formed on both side edges of the step portion having a larger diameter than the end edge of the actual surface and having the center of the arc is R, 20 ° ≦ θe ≦ 60 ° 2 ≦ h ≦ 3 (mm ) 1.5 ≦ R ≦ 3 (mm).

[Operation] To achieve a low AN, reduce the number of water droplets attached to the lower surface of the wire in the longitudinal direction of the wire, and increase the curvature of the water droplets formed on the lower surface and reduce the height of the water droplets. , And improving drainage are key points.

When the concave portion formed by the conditions according to the present invention is formed substantially at the center position of the large-diameter step surface, the concave portion captures water droplets and the number of water droplets decreases, while the capturing force affects the surface tension of the water droplets. The water drops become flattened,
The potential gradient in water drops is reduced, and the generation of AN is greatly reduced.

[Examples] Hereinafter, the present invention will be described with reference to Examples.

In the conventional example, raindrops on the electric wire are collected along the side surface of the stepped portion, move on the large diameter stepped surface, and reach the center of the large diameter stepped surface which is the lower surface side of the electric wire as shown in FIG. At the position, it grows into a large water drop 20 of height Ho.

However, as shown in FIG. 6, a thin interposing wire 3 having a height lower than this is arranged between the thick-walled wires 1 and 1, and the substantially central position is provided between them. If a concave portion 11 having a wide width is formed at the bottom, the water droplet 20 is not sucked into the concave portion 11 and is trapped therein. While the number of water droplets is reduced by this, the surface tension is affected by this suction or trapping force, the water droplet 20 has a large flatness with a large curvature without drooping, and the projection height H ₁ from the wire surface is It is much smaller than Ho.

Based on this finding, Fig. 1 shows that a circular element having a circular cross section with a height (diameter) lower than this is inserted between the thick-walled elements 1, 1 forming a pair of large-diameter step surfaces 10a. Intervene as 3,3,
FIG. 3 is a sectional view of an example according to the present invention in which a recess 11 is formed.

As for the bottom of the recess 11, a virtual concentric circle Q with the electric wire with which the intervening strands 3, 3 are inscribed is defined, and the virtual circle has thick wall strands 1, 2 on both sides.
The intersections that intersect the side surface of 1 are defined as D and D ', and the length δ of DD' is defined as the bottom width.

Further, the difference in the radial direction between the virtual concentric circle Q and the large-diameter step circle P is defined as the depth ho of the recess.

Further, the central angle formed by the side surface of the recess with respect to the center of the wire is θo, and the central angle formed by the surface between the actual surfaces of the large-diameter step portion, that is, the R portions on both sides in FIG. Establish.

As will be easily understood here, the bottom width δ of the recess 11 is
Is too narrow, and the depth ho of the recess 11 is too shallow, the effect is small. Therefore, it can be seen that there may be some critical condition for these.

Furthermore, if there is no significant difference between θe and θo, thick wire 1,
It is conceivable that 1 will project thinly on both sides of the recessed portion 11, which has an adverse effect on electrical characteristics or wind noise prevention characteristics. Therefore, it can be seen that some critical condition may exist between θe and θo.

Fig. 8 is a diagram plotting the relationship between θo / θe and the AN value when an artificial rainfall experiment was conducted using a single conductor as the test material, and Fig. 9 shows the two conductors as the test material and a wind speed of 20 m. It is the diagram which plotted the relationship between (theta) o / (theta) e and the wind noise level at the time of performing the wind noise level measurement experiment in the state which sprayed the wind of / s from the horizontal direction of 2 parallel conductors.

The size and shape of the test material are as described in each figure.

From Fig.8, it is sufficient for AN to have θo / θe of 0.8, but from Fig.9, the wind noise level becomes very poor at 0.8, and when viewed from above the wind noise level, θo / θe is 0.
It turns out that it is necessary to stop below 7.

Further, regarding the lower limit, when θo / θe is 0.2 or less, there is no meaning because there is no change in any characteristic when it is 0, that is, when the recess 11 is not formed.

Therefore, in the present invention, it is understood that it is necessary to form the recess 11 so as to satisfy the condition of 0.2 ≦ θo / θe ≦ 0.7.

In addition, Fig. 7 also uses an electric wire in charge of 810 mm ² ACSR, and θ
In the configuration in which e is 40 °, step h = 2.5 mm, and end R = 1.5 mm, the recess depth ho is selected from 0.5 mm, 1.0 mm, and 2.0 mm, and the horizontal width is the bottom width δ. The vertical axis represents the ratio H ₁ / Ho of the height Ho of the water droplet 20 in FIG. 5 in the conventional example and the height H ₁ of the water droplet 20 in the case of FIG. 6 according to the present invention.
FIG. 4 is a diagram showing the result of measuring the state of water drop height formation by an artificial rainfall experiment.

As can be seen from FIG. 7, the effect of reducing the height of water droplets is hardly recognized unless ho is 1.0 mm or more.

Also, for δ, assuming that ho ≧ 1 mm, δ
It can be seen that the water drop height reduction effect occurs when ≧ 2 mm.

Summarizing the above, it can be seen that the recess 11 according to the present invention needs to satisfy the condition of 0.2 ≦ θo / θe ≦ 0.7 ho ≧ 1 (mm) δ ≧ 2 (mm).

It should be noted that the above is the case of a single conductor, and in the case of a multi-conductor, the requirement described above with reference to FIGS.
In the figure.

20 ° ≤ θe ≤ 60 ° 2 ≤ h ≤ 3 (mm) 1.5 ≤ R ≤ 3 (mm) It is desirable to add a weighting requirement.

In the embodiment shown in FIG. 1, a round wire is used as the interposing wire 3 to form the recess 11. However, as shown in Fig. 3, thick wires
Of course, it does not matter if a thin wire having a height lower than 1,1 is used as the interposing wire, and the large-diameter stepped portion is not necessarily configured as a pair, but one large-diameter stepped portion as shown in FIG. There is no problem even if it is formed, and this has the advantage that the number of water drops attached is naturally small.

[Comparative Example] In the present invention, the outermost twisted layer of the twisted wire is composed of thick-walled wires and thin-walled wires each having a substantially fan-shaped cross section, and a step surface is formed on the outer circumferential surface of the twisted wires due to the difference in the thickness. is doing.

On the other hand, as shown in FIG. 4, it is conceivable to form the recess at the substantially central position of the large-diameter step portion by processing the thick-walled strand itself into an L-shape.

The inventors of the present application initially expected that even an electric wire with a recess having such a structure would have the same outer shape of the stranded wire, and therefore would have the same effect as the present invention.

It is confirmed by experiments that the wind noise characteristics are quite different in the AN characteristics, although there is almost no difference in the effect even with such a structure.

That is, the experimental results comparing the AN characteristics are as shown in FIG.

In FIG. 16, A is the type of FIG. 3 of the examples of the present invention, and B is the type of FIG. 4 which is a comparative example (thick-walled wire itself is processed into an L-shape). All of them are equivalent to a stranded wire size of 810 mm ² , and θe = 45 °, h = 2.5 mm, h
It is an experiment with o = 1.0 mm and δ = 4.0 mm.

C is the type shown in Fig. 10 (A), and the size of the stranded wire is 81
It is a product equivalent to 0 mm ^{2 and} was tested with θe = 45 ° and h = 2.5 mm.

As is clear from FIG. 16, in the structure of FIG. 4 in which the thick-walled wire itself is processed into an L-shape, even if a recess is provided in the large-diameter step portion of the stranded wire, there is a significant difference in AN characteristics. Is observed, and it can be seen that it is worse than the conventional type shown in FIG. 10 (A).

It is believed that the cause of this difference will be clarified in the future, but it is probable that there is a joint between the thick wires that form the large-diameter stepped portion due to the fact that there is a joint between the wires and the capillary tube It is presumed that the water drop suction force due to the phenomenon is involved.

Therefore, it is desirable that the thick-walled wire of the present invention does not have an L-shaped shape, but has a substantially fan-shaped cross section.

[Effects of the Invention] As described above, according to the present invention, it is possible to widely supply to the field an electric wire having excellent wind noise characteristics and AN characteristics without the need for winding a spiral rod or the like. The significance of being able to properly cope with the ultra-high voltage of electric wires is extremely significant.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing the structure of an electric wire according to the present invention, FIG. 2 is a sectional view showing another embodiment, and FIG. 3 is an explanatory sectional view in the case of an element conductor for multiple conductors. FIG. 5 is an explanatory cross-sectional view showing a comparative example of a recessed electric wire, FIG. 5 is a conventional example, and FIG. 6 is an explanatory view showing an adhesion state of water droplets on the electric wire of the present invention, and FIG. 7 is a recessed bottom with respect to a recessed depth. A diagram showing the results of experiments on the effect of width on the height of water droplet formation,
FIG. 8 is a diagram showing the results of measuring the effect of θo / θe on AN, and FIG. 9 is the result of measuring the effect of it on wind sound level, and FIGS. 10 (A) to (C) are three types of graphs. Sectional view showing a test example of an electric wire with a special configuration, Fig. 11 is a plot diagram showing the AN measurement experiment results of each test electric wire shown in Fig. 10, Fig. 12
The figure is an explanatory cross-sectional view of an already proposed element conductor for multiple conductors.
FIG. 13 is an explanatory view showing the behavior of the air when wind is blown on the parallel two conductors, FIG. 14 is a sectional view showing an example of the structure of the already proposed low noise electric wire, and FIG. 15 is explaining each of its constituent parts. FIG. 16 is a diagram showing the AN characteristics of an example of the present invention and a comparative example. 1: Thick wire, 2: Thin wire, 3: Interposed wire, 10a: Large diameter step surface, 10b: Small diameter step surface, 11: Recess.

(72) Kenji Yamamoto, Inventor, Kenji Yamamoto, 1500 Kawajiri-cho, Hitachi City, Ibaraki, Toraura Plant, Hitachi Cable Co., Ltd. (56) References JP 59-96603 (JP, A) JP 1-265409 ( JP, A)

Claims (2)

[Claims] 1. An outermost stranded wire layer of a stranded wire is composed of a thick-walled wire and a thin-walled wire having a substantially fan-shaped cross section, and a step surface is formed in a spiral shape on the outer peripheral surface of the stranded wire due to the difference in the thickness. In this electric wire, an interposing wire having a height lower than that of the thick-walled wires is arranged between the thick-walled wires forming the large-diameter stepped surface, and there is a width at the bottom at a substantially central position of the large-diameter stepped part. Forming a recess,
The central angle formed by the side surface of the recess with respect to the center of the wire is θo,
The central angle formed by the real surface of the large-diameter step surface is θe, the distance between the intersections of the virtual concentric circles with the electric wire inscribed in the bottom of the recess and the thick-walled wires on both sides is δ, and the bottom virtual circle and the large-diameter step Low AN type that is configured so that 0.2 ≦ θo / θe ≦ 0.7 ho ≧ 1 (mm) δ ≧ 2 (mm), where ho is the depth of the concave portion represented by the difference in the radial direction from the circle Low noise electric wire. 2. The electric wire according to claim 1, wherein, in addition to the dimension θe, the height difference between the large diameter step surface and the small diameter step surface is h, and the virtual edge connecting the edge of the real surface of the large diameter step portion and the center of the electric wire. When the radius of curvature of the end arc surface that has a center of the arc on the line and is formed on both side edges of the large-diameter step portion is larger than the end edge of the actual surface, 20 ° ≤ θe ≤ 60 ° 2 ≤ h ≤ 3 (AN) Low AN type low noise electric wire constructed so that 1.5 ≤ R ≤ 3 (mm).