JPH0693327B2 - Low wind noise and low AN electric wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention can reduce noise generated when an electric wire is subjected to wind pressure, and at the same time, audible noise generated by a corona generated from the electric wire during rainfall. The present invention relates to a novel overhead power transmission line capable of reducing (hereinafter referred to as AN) and an efficient overhead wire method.

[Prior Art] In order to reduce wind noise generated when an electric wire is subjected to wind pressure, the applicant proposed a technology for winding a spiral rod around the outer circumference of the electric wire earlier and has been widely put to practical use nationwide. , Its excellent effect has been demonstrated.

However, in recent years, it has been planned that the transmission voltage of the overhead power transmission line will be extremely high voltage such as so-called UHV transmission of 500,000 V to 1 million V. Problems have started to be raised.

That is, when the spiral rod is separately wound around the outer circumference of the electric wire, the spiral rod projects to the surface of the electric wire, so that the wind pressure load greatly increases, while the surface of the spiral rod in ultra-high voltage or ultra-high voltage transmission This is because it is considered that the concentration of the potential gradient occurs in the area, and the above-mentioned AN is likely to occur particularly during rainfall.

As a result, it was found that by smoothing the outer surface of the wire, even if the protrusion on the outer circumference of the wire is made small, a sufficient wind noise reduction effect can be exhibited, and the low cross-sectional structure as shown in FIG. I proposed a wind sound cable. (Patent Fair 1-3388
4) This is a large-diameter wire with a smooth surface by twisting a wire with a large fan-shaped cross-section (hereinafter referred to as a fan-shaped wire) 1 and a thin fan-shaped wire 2 in the radial direction of the wire to the outermost layer of the wire. A step surface 10a and a small-diameter step surface 10b having a smooth surface are formed to reduce wind noise at this step.

Smoothing the outer surface of the electric wire is to form the electric wire into a shape close to a cylinder.

Now, consider a cylinder model and consider its relation to wind noise generated when wind blows on it.

When wind blows on a cylinder, there is a viscous boundary layer near the surface of the cylinder, which has a slow velocity, and there is a slow velocity boundary layer.In the region of pressure increase in this boundary layer, the flow separates from the cylinder surface and swirls backward. To form. Due to this separation, lift F _L and drag F _{D in the} flow direction are generated in the cylinder.

Wind noise generated from the electric wire is pressure noise related to F _L,
The whirlpool is not the sound source.

In order to reduce wind noise, the fluctuation component Δ
It is necessary to reduce the F _L, for this purpose, it is necessary to control the boundary layer around the wire. Smooth surface or 16th
The boundary layer is roughly classified into laminar flow and turbulent flow depending on whether it is rough like the conventional twisted wire shown in the figure, and its qualitative properties are symmetrical.

The scale of separation is strong and large on a smooth surface, that is, on a laminar boundary layer, which causes large wind noise.However, since the thickness of the boundary layer is small, the low wind noise promoting effect due to the addition of protrusions is turbulent. Can be said to be greater than.

The low wind noise wire shown in Fig. 13 was proposed against the background of the theory of the mechanism described above.With the mechanism described above, a height difference of 1 mm is sufficient for the stepped portion. It has the same effect of preventing wind noise as an electric wire wound with a spiral rod of several mm. Therefore, the protruding portion on the surface of the electric wire can be made significantly smaller, and the AN caused by the protruding portion on the surface of the electric wire can be greatly reduced.

[Problems to be Solved by the Invention] With the configuration as shown in FIG. 13 described above, it is possible to reduce wind noise of an electric wire and at the same time reduce AN, but there is a problem at all.

That is, in the case of an electric wire having a configuration as shown in Fig. 13, when the electric wire is used and is in the so-called aging state, raindrops widely spread on the high step surface side, and even if it grows large, it drops due to surface tension. It is also possible that corona is likely to be generated from the large-sized raindrops.

FIG. 17 is an explanatory view showing a state in which the raindrops 20 are thus widely attached, and the height of the raindrops 20 increases as the raindrops 20 become larger.
It is possible that H _O will also be high.

FIG. 12 is an improved example of the electric wire shown in FIG. 13 in which such a fear is eliminated. A groove 11 is formed in the middle portion of the large diameter step surface 10a.
Is formed. By forming the groove portion 11, raindrops 20 are captured in the groove portion 11 as shown in FIG. 18, and the raindrops thus captured are squeezed, and the raindrops are cut and fall before they grow into large raindrops. At the same time, the remaining raindrops 20 in the remaining groove 11 are recessed inward due to the surface tension and do not form a protruding portion that causes corona generation.

As described above, as a result of the subsequent experiments, it became clear that the electric wire having the structure shown in FIG. 12 still has a problem to be solved.

First, in order to satisfy the output characteristics, it is important to consider the height difference h for preventing wind noise to be as small as possible and to increase the opening angle θ. Is required to be as small as possible and to be close to the surface of a smooth cylinder.

Secondly, it is necessary to improve the AN characteristics in consideration of the groove portion formed on the protruding surface so as not to affect the wind noise reduction effect. The influence of the groove shape on the improvement of AN characteristics is large.
Since the characteristics may deteriorate, it is necessary to make the shape based on sufficient consideration.

In view of the above circumstances, the object of the present invention is to
The electric wire shown in the figure has been further improved to have a low wind noise and a configuration that is the optimum condition for both low wind noise and low AN characteristics.
It aims to provide low AN wires.

[Means for Solving the Problems] In the first aspect of the present invention, the outermost stranded wire layer of the stranded wire is composed of a thick-walled wire and a thin-walled wire that are substantially fan-shaped in cross section, and In an electric wire in which a smooth step surface is formed on the outer circumferential surface of a stranded wire in a spiral shape, a groove is formed at approximately the center of the large-diameter step surface, and the central angle made by the actual surface of the large-diameter step surface is θe. When the step is h, the equivalent outer diameter of a normal wire with a smooth surface is de, and the outer diameter of the normal wire is d, de ≧ 28.5mm 20 ° ≦ θe ≦ 60 ° 2mm ≦ h ≦ 3mm de / d ≧ 1.0 Secondly, in order to further reduce the wind noise, the second outermost layer of the twisted wire has a thick-walled wire and a thin-walled wire that are almost fan-shaped in cross section. An electric wire that has a smooth stepped surface that is spirally formed on the outer circumferential surface of the stranded wire due to the difference in wall thickness. , A groove is formed at approximately the center of the large-diameter step surface, the central angle formed by the actual surface of the large-diameter step surface is θe, the height difference is h, and the equivalent outer diameter of a surface-smooth wire to a normal wire is de, usually De ≧ 28.5mm 20 ° ≦ θe ≦ 60 °, where d is the outer diameter of the wire, δ is the depth of the indentation formed by the wires forming the small stepped surface between adjacent wires, and t is the opening width. 2 mm ≤ h ≤ 3 mm de / d ≥ 1.0 δ ≤ 1.5 mm t ≤ 3 mm, in which case the intervening wire forming the groove is the wire forming the large diameter step surface. It is composed of one separate wire, and further, the interposing wire forming the groove is formed in an arc shape facing outward, and the depth from the virtual outer diameter end of the large diameter step surface to the arc upper surface is h _o , 1 mm ≤ h _o ≤ 2 mm 3 mm ≤ W ≤ 9 mm, where W is the width of the groove bottom.

[Operation] By imparting a critical condition to each of the configurations as described above, the AN characteristics can be further improved while appropriately exhibiting the low wind noise effect.

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

FIG. 1 is a sectional view showing the structure of an embodiment according to the present invention, and FIG. 2 is an explanatory view showing an example of its actual dimensions.

The electric wire according to the present invention is premised to be used for transmission of ultra-ultra-ultra-high voltage such as 500,000 V to 1 million V, which has a high surface potential gradient and causes AN to be generated due to deposition of raindrops during rainfall. This is because it is easy to do.

Fig. 3 shows the relationship between the corona hum noise (AN) during light rain (1 mm / hr) in 500,000 V power transmission and the outer diameter of the wire for each standard ACSR wire size using a corona gauge. It is the diagram shown.

As is clear from FIG. 3, the AN increases dramatically as the wire diameter decreases. It is desirable for the AN to be null, but it is difficult to achieve silence. Since AN is what perceptual, but not criterion that is acceptable as long as how much level, AN properties compared to ACSR410mm ² equivalent which are widely used in current 500,000 V transmission line deteriorate It is desirable not to.

Therefore, the object of the present invention is that the outer diameter d of the electric wire is 28.5 mm or more.

Further, the object of the present invention is to make the AN of the conventional electric wire and the AN of the wind noise countermeasure electric wire have substantially the same characteristics. For this purpose, it is necessary to make the equivalent outer diameter de (average outer diameter when the projected area is aligned in the longitudinal direction) of the wind noise countermeasure electric wire equal to or more than that of the conventional electric wire. It is the diagram which plotted the relationship of AN and ratio de / d of equivalent outside diameter de and outside diameter d of the conventional electric wire corresponding to it.

It is clear from Fig. 4 that AN increases as de / d becomes smaller than 1.0.

Fig. 6 shows a normal 810m with the outer diameter d = 38.4mm shown in Fig. 16.
m ² ACSR and its equivalent outer diameter de is slightly larger 2nd
The electric wire according to the present invention whose dimensions are shown in the figure and the above 81
This is a plot of the relationship between each Gmax and AN for each low wind noise electric wire in which a conventional spiral rod is wound around 0 mm ² ACSR.

It can be seen that by making the equivalent outer diameter of the electric wire according to the present invention slightly larger than the outer diameter of the conventional electric wire, an AN characteristic almost equivalent to that of the conventional electric wire is exhibited.

That is, it is understood from the above results that the present invention requires a critical condition of de ≧ 28.5 mm de / d ≧ 1.

The central angle θe made by the real surface of the large-diameter step surface and the critical condition for the height h of the step in the present invention are the critical conditions for the wind noise characteristics, and are derived from the data in FIG. is there.

From FIG. 19, it is possible to see the optimum condition for 20 ° ≦ θe ≦ 60 ° 2 mm ≦ h ≦ 3 mm.

In the structure shown in FIG. 13, h is required to be 1 mm or more. However, the present invention is intended for multiconductors particularly in response to ultrahigh pressure, and as a result, a lower limit of 2 mm occurs.

On the other hand, considering the upper limit of h, as can be seen from FIG. 19, the larger h is, the greater the wind noise reduction effect is. But,
When h is large, the electrical characteristics are inevitably deteriorated, it is difficult to twist the wire, and it is also difficult to wire, and the wind pressure load after the wire is significantly increased.

Considering the conductors for multiple conductors, the upper limit of h is 3.0 mm. That is, when the electric wire for multiconductor is used, 2.0 ≦ h ≦ 3.0 (mm).

It has been described above that in order to make the step h as small as possible and to enhance the low wind noise effect, it is necessary to make the surface of the twisted wire as smooth as possible and bring it closer to a cylinder.

This means that the small-diameter step surface also needs to be smoothed.

In order to process the fan-shaped cross-section wires economically and without any problems in terms of strength, it is preferable to make the corners as shown in (a) in FIG. 5, but as shown in (b). It doesn't matter. In the experiment shown in FIG. 5, the one having the radius of curvature r as shown in (a) was used, but this result is applicable to (b) as well.

In each case, an experiment was carried out for electric wires of the same size with r = δ = t / 2. However, the sample with r = 0 is a model using a cylinder, and the others are actual strands.

The increase in wind noise energy should be doubled, that is, 3 dB, but the variation was taken into account ± 3 dB.

From FIG. 5, it can be seen that the condition satisfying the condition within 3 dB is δ ≦ 1.5 mm t ≦ 3 mm.

Therefore, in the present invention, the δ and t are also defined and the wind noise is further reduced by satisfying the above conditions.

If the number of large-diameter stepped surfaces of the electric wire is increased, the number of protrusions on the electric wire surface is increased accordingly, resulting in deterioration of electrical characteristics and an increase in wind pressure load. The fatal problem is that as the number of protrusions increases, the number of water droplets, that is, the sound source of AN increases, and it is desirable that the number of low wind noise effects be the minimum.

Therefore, it is desirable that the large-diameter step surface and the small-diameter step surface are respectively provided at one place or a pair.

The relationship between the logarithm of the large diameter step surface and the wind noise level and AN level is as shown in FIG.

On the other hand, although there have been many studies and proposals concerning AN reduction of conventional electric wires, the mechanism is complicated and there is no dogma. The main cause of this is the behavior of water drops adhering to the surface of the wire and the superposition of capillary action between the wires.

Therefore, the inventors conducted some experiments using the groove portion 11 in FIG. 1 as a parameter.

Radius of curvature ρ determined by twist pitch (when 810 mm ² ρ
Approximately 240 mm) A disc shown in Fig. 8 is sandwiched by coaxial discs with the same wire width, and the number n of the discs, the total width W of the groove bottom and the groove depth h _o are changed to cause precipitation from the top. Then, an experiment of drainability was conducted. This is because AN is considered to be determined by two contradictory factors of water leakage and water drainage. That is, it is necessary to roughen the surface in order to increase the water leakage property, but since the leakage angle is large, the water droplets are stable and the water droplets do not drop on the contrary, and the AN level does not decrease beyond a certain limit. In order to lower the level, it is necessary to make the projection of the water droplet small (the leakage angle is large), improve the water drainage property, and drop the water droplet quickly. Therefore, complicated capillary force, surface tension of water droplets, mass of water droplets, and the like pose problems, but none of them has been scientifically elucidated at this time.

The experimental results are shown in FIG. The symbols in the figure represent average values, and the vertical axis represents the time required to drop 10 water droplets. As a result, there is a range in which the fall time is small for h _o and W,
Further, it has been clarified that the number n of the wires 3 constituting the groove portion 11 is preferably one as shown in FIG. When W becomes large, it becomes an independent water drop that does not leak to the side surface of the groove, and this water drop does not fall because of good water leakability.
It is presumed that in the configurations of 3 ₁ and 3 _{2 in} Fig. 10, water drops are blocked by the capillary force between the strands that make up the groove, making it difficult to drop.

From this result, it is clear that satisfying the condition of 1 mm ≦ h _o ≦ 2 mm 3 mm ≦ W ≦ 9 mm n = 1 should be considered from the viewpoint of water drainage.

This result is not the result of AN measurement. Fig. 6 shows the result of using a prototype electric wire based on this result.
This proves that the concept of water drainage described above is valid.

Experiments were also conducted on the shapes shown in FIGS. 14 and 15 in the same manner as above, but the water-drainability was extremely poor.
This has the effect of stabilizing the water droplets in the shape of FIG. 14, and in the shape of FIG. 15, when W ′ = 0, h _o = 2m in FIG.
The effect was about the same as m, n = 2, but in other cases the drainage was poor. This is considered to be because water droplets wrap around the projections on the strands, which impairs water drainage.

Accordingly, the surface 3a of the interposing elemental wire 3 forming the groove portion 11 is composed of one of the elemental wires different from the elemental wire 1 forming the large-diameter step surface, and the surface 3a of the interposing elemental wire 3 forming the groove portion faces outward. It can be seen that it needs to be formed in an arc shape.

Incidentally, as for the Atsunikumotosen 1 side, shown in Figure 11 1 ₁
And 1 not at all permissible even ₂ plural as.

As mentioned above, the phenomenon is extremely complicated and AN is a troublesome problem.
It can be said that the prospect stood measures.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide an electric wire having excellent wind noise characteristics and AN characteristics. In particular, conventional spiral rods have limited countermeasures. The fact that the countermeasures could be achieved should be highly evaluated, and the wind load was large in the spiral rod countermeasure, whereas in the present invention, it is possible to increase the load in the same or a slight amount as the conventional electric wire. It can exhibit a number of excellent advantages such as being extremely economical when constructing railway tracks.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of an electric wire according to the present invention, FIG. 2 is a sectional view of another embodiment in which actual dimensions of the outer circumference are included, and FIG. 3 is a diagram showing a relationship between an outer diameter of an electric wire and AN. FIG. 4 is a diagram showing the relationship between de / d and AN, FIG. 5 is a diagram showing the relationship between the size of the indentation of the strands forming the small diameter step surface and the wind sound level, and FIG. 6 is the present invention. FIG. 7 is a diagram showing the results of measuring the relationship between the AN characteristic of each of the example, the conventional electric wire and the spiral rod wound electric wire, and FIG. 7 is a line for measuring the water drop drop characteristics depending on the depth of the groove and the number of interposing wires. FIGS. 8 to 10 are explanatory views showing the constitution of each sample when the experiment of FIG. 7 is performed, and FIG. 11 is an explanatory view showing an example in which the number of thick strands is plural,
Figures 12 and 13 are cross-sectional views of the proposed wire, Figures 14 and 15 are two explanatory views of another sample for water drop experiments, and Figure 16 is a cross-sectional view of a conventional 810mm ² ACSR, and Figures 17 and 18 FIG. 19 is an explanatory diagram showing how water drops adhere to the surface of the electric wire, and FIG. 19 is a diagram showing the results of measuring the effect of the surface step h and the central angle θe of the smooth actual surface of the high step surface on the sound pressure level, FIG. 20 is a diagram showing the relationship between the logarithm of the large-diameter step surface and the relative levels of wind noise and AN. 1: Thick wire, 2: Thin wire, 3: Interposed wire, 3a: Interposed wire surface, 10a: Large diameter step surface, 10b: Small diameter step surface, 11: Groove part.

Front Page Continuation (72) Inventor Toshio Yamada 1-3-3 Uchisaiwaicho, Chiyoda-ku, Tokyo Within Tokyo Electric Power Co., Inc. (72) Inventor Takao Fujishima 1-3-1 Uchiyuki-cho, Chiyoda-ku, Tokyo Tokyo Electric Power Co., Inc. In-house (72) Inventor Katsuyuki Urasawa 1-3-3 Uchisaiwai-cho, Chiyoda-ku, Tokyo Within Tokyo Electric Power Co., Inc. (72) In-house Masahiro Ogawa 1-3-1 Uchisai-cho, Chiyoda-ku, Tokyo Within Tokyo Electric Power Co., Inc. (72) Inventor Kiyoshi Shimoshima, 3550 Kidayo-cho, Tsuchiura-shi, Ibaraki Hitachi Metals Co., Ltd. (72) Inventor Yuji Karashi 3550, Kida-yomachi, Tsuchiura-shi, Ibaraki Hitachi Metals Co., Ltd. (72) Inventor Takashi Kawakami 3550 Kidayo-cho, Tsuchiura-shi, Ibaraki Hitachi Wire & Cable Co., Ltd. (72) Kenji Yamamoto Kenji Yamamoto 1500, Kawajiri-cho, Hitachi-shi, Ibaraki Hitachi Cable Co., Ltd.Toyoura factory (72) Inventor Hitoshi Kikuchi 1500 Kawajiri-cho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Ura Plant (72) Inventor Hiroaki Ito 1500 Kawajiri-cho, Hitachi City, Ibaraki Prefecture Torayura Plant, Hitachi Cable Co., Ltd. (56) References JP-A-59-96603 (JP, A) JP-A-59-221906 (JP) , A) JP 60-1705 (JP, A) JP 60-7008 (JP, A) JP 60-189809 (JP, A) JP 60-189810 (JP, A) JP 63-116310 (JP, A) JP-A-4-39817 (JP, A)

Claims (4)

[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 smooth step surface is spirally formed on the outer peripheral surface of the stranded wire due to the difference in the thickness. In the formed electric wire, a groove is formed at approximately the center of the large-diameter step surface, the central angle formed by the actual surface of the large-diameter step surface is θe, the height difference is h, and the surface smooth wire is equivalent to a normal electric wire. When the outer diameter is de and the outer diameter of the normal wire is d, de ≥ 28.5mm 20 ° ≤ θe ≤ 60 ° 2mm ≤ h ≤ 3mm de / d ≥ 1.0 AN electric wire. 2. The outermost stranded wire layer of the stranded wire is composed of a thick-walled wire and a thin-walled wire having a substantially fan-shaped cross section, and a smooth step surface is spirally formed on the outer peripheral surface of the stranded wire due to the difference in the thickness. In the formed electric wire, a groove is formed at approximately the center of the large-diameter step surface, the central angle formed by the actual surface of the large-diameter step surface is θe, the height difference is h, and the surface smooth wire is equivalent to a normal electric wire. When the outer diameter is de, the outer diameter of a normal electric wire is d, the depth of the recess formed between adjacent wires by the wires forming the small diameter step surface is δ, and the opening width is t, de ≧ 28.5 mm 20 Low wind noise and low AN electric wire which is configured so that ° ≦ θe ≦ 60 ° 2mm ≦ h ≦ 3mm de / d ≧ 1.0 δ ≦ 1.5mm t ≦ 3mm. 3. The low wind noise / low AN electric wire according to claim 1 or 2, wherein the interposing element wire forming the groove is composed of one element wire different from the element wire forming the large diameter step surface. . 4. The depth of the large diameter step surface from the virtual outer diameter end to the upper surface of the arc is defined as h ₀ , and the width of the groove bottom is defined as W, with the interposing element wire forming the groove being formed in an arc shape facing outward. 4. The low wind noise and low AN according to claim 3, wherein 1 mm ≦ h ₀ ≦ 2 mm 3 mm ≦ W ≦ 9 mm
Electrical wire.