JPH0245412B2 - TEISOONDENSEN - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved low-noise electric wire, and particularly to a low-noise electric wire that has various effects of improving corona noise characteristics, reducing wind pressure (wind noise), and preventing icing and snow accumulation.

As shown in Fig. 1, a low-noise electric wire is constructed in which a spiral rod 11 is wound around the outer circumference of the electric wire 10 to prevent regular periodization of air fluid around the outer circumference of the electric wire, thereby suppressing wind noise generated by the electric wire due to the wind. Are known.

However, as shown in the explanatory cross-sectional view in FIG. 2, such a spiral rod 11 has a circular cross section and is wound around an electric wire 10 that has the same circular cross section. Such problems are expected.

First, since the spiral rod 11 acts as a protrusion on the surface of the electric wire 10, the potential gradient (Gmax) on the surface increases, which may worsen the corona noise characteristics. As shown in Figure 2, a concave portion 11a is formed by the electric wire 10 having a circular cross section and the spiral rod 11 having a circular cross section as well, and there is a risk that supercooled water droplets may be trapped in this portion and become susceptible to icing 12. That's true.

Therefore, in order to eliminate the above-mentioned problems, it has been proposed to tightly wind two rods or to wind a spiral rod with a non-circular cross section. Although these previously proposed shapes have certain effects on corona noise (AN) and icing, in the case of two closely wound layers, there is no major difference in icing from the conventional structure shown in Figure 1, and the AN The effect is insufficient and further improvement is desired, and those with a non-circular cross section are extremely difficult to manufacture and have many problems from an economic standpoint. Furthermore, detailed experimental results regarding AN indicate that a molded body with a non-circular cross-section made up of multiple pieces is better than a molded body with a non-circular cross-section made entirely of one piece.
It was also found to be effective in reducing AN. This is thought to be because when the structure is made up of multiple parts, capillary action occurs between the parts, allowing water droplets to be absorbed and flowed more easily, resulting in better water drainage and greatly improving the AN characteristics caused by the adhesion of water droplets. .

The present invention was made in view of the above-mentioned circumstances, and the cross-sectional shape of the spiral rod is circular, which is easy to form. When we looked at the cross-sectional shape of the spiral rod as a whole, we found that the entire spiral rod had a non-circular cross-section, and we found the optimum conditions for the diameter of each of the wires to be wound. be.

A specific example will be explained below.

3 and 4 are schematic cross-sectional views of the low-noise electric wire according to the present invention.
The electric wires 1 and 2 are the respective wound rods constituting the spiral rod 20 according to the present invention.

The spiral rod 20 is essentially composed of three rods, with a large-diameter rod 1 placed in the center, and small-diameter rods 2 placed on both sides of the rod so as to sandwich the large-diameter rod. and is wound around the outer periphery of the electric wire 10. In this way, since there are small diameter rods 2 on both sides of the large diameter rod 1 in the center, there is a recessed part 11a as seen in Fig. 2.
is no longer present, and the effect of trapping supercooled water droplets is significantly reduced. Moreover, Spiral Rod 20
Since the rod is substantially composed of divided pieces made up of three rods, capillarity occurs significantly between the rods, greatly preventing the formation of water droplets, and thereby greatly improving the AN characteristics. Furthermore, when looking at the overall outer shape of the spiral rod 20, it has a gentle curvature as shown by the dotted line in FIG. 3, so it effectively reduces corona characteristics, wind pressure, and wind noise.

Fig. 5 is a diagram comparing the wind pressure characteristics of the conventional example and the present invention ^.
As shown in the ACSR diagram, A has two spiral rods with the same diameter (6.0mm) facing each other, and B has two spiral rods in close contact with each other.
The case is shown in which each book is wound, and in the case of the present invention, the case is shown in which three rods are wound as shown in the figure, with a large rod having a diameter of 6.0 mm and a small rod having a diameter of 3.0 mm.

As is clear from Fig. 5, it is clearly seen that the present invention has a remarkable wind pressure reduction effect.
This wind pressure reduction effect is directly reflected in the wind noise reduction effect described below.

FIG. 6 is a diagram showing the wind noise reduction effect, and the configuration of each electric wire is the same as in FIG. 5. In the 410 mm ² ACSR without countermeasures, a noise peak is formed around 150 Hz, but in Conventional Example B and the present invention, this peak is significantly reduced. However, as is clear from a comparison between Conventional Example B and the present invention, the wind noise reduction effect of the present invention is even more remarkable than that of Conventional Example B. This is thought to be due to the effect of disturbing the air fluid.

As described above, it has been found that the electric wire according to the present invention exhibits excellent effects, but regarding the configuration of the spiral rod according to the present invention, the large diameter rod 1 and the small diameter rod 2 may have any diameter. It won't be. That is, if the small diameter rod is too small, there will be no significant difference from the case of one large diameter rod, and if the small diameter rod is too large, there will be no significant difference from the case of the conventional row B.

The inventors investigated the relationship between d ₁ and d ₂ when the diameter of the large diameter rod is d ₁ and the diameter of the small diameter rod is d ₂ by using various combinations of spiral rods as test materials. Conducted wind tunnel and corona experiments.

Figure 7 shows an example, 410mm ²
It is a dynamic diagram showing the relative level change of wind noise and corona noise by variously changing the diameter of the small rod placed on both sides of the large rod of 6.0 mm diameter wound around the ACSR. Regardless of whether _d2 becomes thinner or thicker than _d1 , both the wind noise reduction effect and the audible noise (AN) reduction effect due to corona deteriorate. It has been found that such a tendency is similarly observed in electric wires of various sizes other than the case shown in FIG.

Therefore, by comprehensively considering the characteristics of both the wind noise level and the corona noise level that were confirmed through experiments, and the anti-icing and snow formation effect of the small-diameter rod mentioned above, we decided to increase the ratio of _d2 to d1 in order to coordinate these _three factors. If we define the range, the lower limit of d ₂ is 0.3d ₁ and the upper limit is 0.8d ₁ .

In other words, in the range where d ₂ is smaller than 0.3d ₁ , the seventh
As seen in the figure, the effect of reducing the wind noise level disappears, so it should be excluded.Also, in the range where _d2 is larger than _0.8d1 , there is still a slight reduction effect on both wind noise and AN level, but small diameter The thickness of the rod is limited from the viewpoint of preventing ice and snow from accreting on the rod. By the way, as long as it is within the range of 0.3d ₁ ≦d ₂ ≦0.8d ₁ , it is almost the same as far as corona noise is concerned.
This provides a reduction effect of 2 dB or more.

Here, we will further consider the geometrical conditions within the above range of 0.3d ₁ ≦d ₂ ≦0.8d ₁ and examine whether the optimal condition within the range is Nabe.

First, the case where the AN value is the minimum is a geometric configuration in which the potential gradient on the surface of the spiral rod 20 is relaxed, and as shown in Fig. 3, the large diameter rod 1 and the small diameter rod 2 are large. This is a case where the rod 1 is inscribed in a virtual circle P (shown with a dotted line in FIG. 3) whose radius is the diameter d ₁ of the diameter rod 1.

Diameter d ₁ of large diameter rod 1, diameter d 2 of small diameter rod ₂
When the diameter of the electric wire 10 is D, the relationship of equation (1) holds true when the electric wire 10 is inscribed in the virtual circle.

d ₂ = [d ₁ (D + d ₁ )] / (2D + d ₁ )...(1) Next, the spiral rod 20 applies wind pressure (wind noise)
We will consider the most preferable configuration for this. When the wind pressure is at its minimum, as shown in Figure 4, the small diameter rod 2 is connected to the large diameter rod 1 and the electric wire 10.
This is a case where the configuration is such that it is inscribed in the tangent Q to .

In this case, each condition has the relationship shown in equation (2).

d ₂ = (D・d ₁ )/(D+d ₁ ) ² ...(2) Therefore, considering both the conditions where the AN value is the minimum and the wind pressure and wind noise are the minimum, finding the optimal range of d ₂ is ( 3) As shown in equation.

(D・d ₁ )/(D+d ₁ ) ² ≦d ₂ ≦ [d ₁ (D+d ₁ )]/(2D+d ₁ ) …(3) Now, 410 mm ² ACSR is used as the electric wire, and 6.0 mm bare wire is used as the large diameter rod. In this case, the range of d ₂ for a small diameter rod that satisfies equation (3) above is 2.8 mm ≦ d ₂ ≦ 3.3 mm. Therefore, the practical value of d ₁ and d ₂ aiming at improving the AN value, wind pressure, and wind noise is It can be seen that the most excellent condition is d ₂ =(d ₁ /2) within the range of 0.3d ₁ ≦d ₂ ≦0.8d ₁ .

Of course, these are the best conditions for the present invention, and the present invention is not limited to these conditions. As we have already seen, 0.3d ₁ ≦
Excellent effects are achieved when d ₂ ≦0.8 d ₁ , and of course the values of d ₁ and d ₂ should be selected based on various actual circumstances such as the size of the wire and spiral rod, economic conditions, working conditions, etc. Bye.

As detailed above, the low-noise electric wire according to the present invention is able to improve the AN value, wind pressure, and wind noise, which were difficult points in the conventional spiral rod winding method, and to coordinate the effect of preventing icing and snow formation. Therefore, its usefulness is highly evaluated.

[Brief explanation of the drawing]

Figure 1 is a sketch showing a conventional low-noise electric wire, Figure 2
The figure is a schematic cross-sectional view, Figures 3 and 4 are explanatory diagrams of the low-noise electric wire according to the present invention, and Figures 5 to 7 are wind pressure characteristics, wind noise characteristics, wind noise and rod diameter ratio according to wind tunnel experiments, respectively. FIG. 3 is a diagram showing the variation characteristics of corona noise level. 1: Large diameter rod, 2: Small diameter rod, 10: Electric wire, 11, 20: Spiral rod.

Claims (1)

[Claims] 1. A spiral rod wound around the outer periphery of an electric wire is composed of a large-diameter rod placed in the center and small-diameter rods placed on both sides of the large-diameter rod, and the diameter of the large-diameter rod is d. _1. A low-noise electric wire configured such that 0.3d ₁ ≦d ₂ ≦0.8d ₁ where d ₂ is the diameter of the small diameter rod.