JPS6353764B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a low-wind-noise armor, and particularly to an armor-rod that is attached to a jumper wire of an overhead power transmission line to reduce wind noise. BACKGROUND OF THE INVENTION Conventionally, jumper wires of overhead power transmission lines have been fitted with armor rods to reduce stress caused by wire vibration and to prevent wire damage and disconnection due to arcing. However, conventional Armarod wires are simply twisted and wound metal wires having a circular cross section around the outer periphery of jumper wires, and no consideration has been given to exhibiting low wind noise characteristics.
If the overhead power transmission line itself has low wind noise characteristics, the jumper wire will also have similar characteristics.
It is not necessary to specially provide the above characteristics with Armarod, but jumper wires in existing overhead power transmission lines that do not have such characteristics may be exposed to winds of about 10 m/s or more, A Kahlmann vortex is formed, producing a wind sound called Eolus sound, which resembles a hum. Such wind noise causes discomfort to residents near the steel tower, so it is desired to reduce it. Figure 1 shows the sound pressure level (dB) of wind noise generated by conventional jumper wires by frequency (Hz) band.
FIG. In this measurement example, the sound pressure level is measured for each 1/3 octave width, which is obtained by dividing one octave width A into three equal parts from the frequency band having the maximum sound pressure level, by evaluating the sound pressure level for 10 seconds. The higher the sound pressure level is, the harsher the wind noise becomes, and the sound pressure level of conventional jumper wires was extremely high. In particular, wind noise in the frequency band of the maximum sound pressure level becomes a very harsh sound. Therefore, an object of the present invention is to provide a jumper wire with a low sound pressure level and low wind noise. Hereinafter, specific embodiments of the present invention will be described based on the drawings. FIG. 2 is a cross-sectional view of the Armarod 10 of the embodiment attached to the jumper wire 11, FIG. 3 is a cross-sectional view of the Armarod element wire 12, and FIG. 4 is a partially omitted plan view of the jumper wire 11 with the Armarod 10 attached. It is a diagram. The armarod 10 described above is constructed by tightly winding a plurality of wires 12 around the outer periphery of a jumper wire 11 in a spiral shape. The cross-sectional shape of the wire 12 is as shown in FIG.
It is on a concentric circle with , and both sides are jumper wire 11
has a constant angle θ with respect to the center of Further, both corners of the outer surface are formed into circular arc surfaces with a radius of curvature r.
By selecting the above angle θ such that θ=360/n (where n is a positive integer), n strands 12 can be densely arranged around the outer periphery of the jumper wire 11. Further, as shown in FIG. 4, the above-mentioned wire 12 is previously formed into a spiral shape, and its inner diameter is the same as that of the jumper wire 11 before being attached to the jumper wire 11.
The jumper wire 1 is formed slightly smaller than the outer diameter of the jumper wire 1.
1, it is made to wrap around tightly due to its elasticity. When the strands 12 as described above are tightly wound around the outer periphery of the jumper wire 11, a plurality of spiral grooves 13 are formed by butting the arcuate surfaces of the outer corners of each strand 12, and the gaps between the adjacent grooves 13 are The opening angle θ with respect to the center of the jumper wire 11 matches the angle θ of both side surfaces of the wire 12 described above. The idea for the Armarod of this embodiment was based on the analysis of the conventional Armarod in which a wire with a circular cross section is wound, and the formation of a Karlmann vortex that occurs in a cylinder or pipe with a smooth outermost layer. By the way, in order to find a suitable elongated shape for the Armarod 10, the radius of curvature r (m), the wire diameter (outer diameter) D (m), and the angle (hereinafter referred to as opening angle) θ (degrees) with respect to the center of the adjacent groove 13 are determined. ) and the maximum sound pressure level difference ΔL (dB) was determined through experiments. Here, the maximum sound pressure level difference ΔL (dB) is
This refers to the difference between the maximum sound pressure level of a conventional jumper wire wound with a circular wire and the maximum sound pressure level of a jumper wire equipped with Armarod of this embodiment having the same diameter. In this experiment, an 80cm x 80cm low-noise wind tunnel was used, and the Armarod 10 was placed 50cm from the air outlet. In addition, in the experiment, the wind speed was 15m/
The test was conducted at two speeds: 25 m/s and 25 m/s. in this way,
The reason why two representative values of wind speed were selected is as follows. That is, when the wind speed is 15 m/sec or less, the sound pressure level of the wind noise caused by the jumper wire is small, so there is no need to consider wind noise countermeasures. On the other hand, the wind speed is 35m/
This is because if the noise is longer than 1 second, the surrounding noise due to the wind speed becomes louder than the wind noise due to the jumper wire, which is called background noise, so the wind noise due to the jumper wire is not a problem. Under such conditions, the radius of curvature r (m) of the strand 12 of the Armarod 10 of this embodiment, the outer diameter D (m) including the Armarod 10,
Maximum sound pressure level difference ΔL (dB) by wind speed when comparing the actual measurement results with the groove opening angle θ (degrees) suitably different and the actual measurement results of a conventional jumper wire with the same diameter D (m) are shown in Table 1.

【table】

[Table] FIG. 6 is a characteristic diagram in which the sound pressure level of wind noise is measured in each frequency band for a jumper wire equipped with a conventional Armarod and a jumper wire equipped with the Armarod 10 shown in FIG. 2. In particular, the solid line indicates the case of the conventional Armarod, and the dotted line indicates the sound pressure level of the Armaroud 10 having the structure shown in FIG. Here, the difference between the sound pressure level of the conventional Armarod and the sound pressure level of the Armarod 10 of this embodiment in the frequency band where the maximum sound pressure level occurs, that is, the maximum sound pressure level difference is indicated by ΔL. In Table 1, the maximum sound pressure level difference ΔL (dB)
If is negative (-), the Armarod 1 of this embodiment will
0 means a lower maximum sound pressure level.
As a result of examining this Table 1, the diameter D (m) of the electric wire
It is thought that there is a correlation between the radius of curvature r (m) and the radius of curvature r (m) in reducing wind noise. That is, the radius of curvature r
(m) and diameter D of jumper wire including armarod
(m), the so-called curvature radius ratio r/D, has a correlation with the maximum sound pressure level difference ΔL. On the other hand, the change in the maximum sound pressure level difference ΔL with respect to the change in the opening angle θ (degrees) is slight compared to the radius of curvature ratio r/D, but it cannot be said to be completely unrelated. Therefore, it is appropriate to express the relationship between the opening angle θ and the maximum sound pressure level difference ΔL by the logarithm (ie, logθ) of the opening angle θ (degrees).
Therefore, it has been found that if the maximum sound pressure level difference ΔL is expressed in relation to the shape of the Armarod 10, the shape factor K of the Armarod 10 can be expressed by the following equation. K=10·r/D+logθ Therefore, when the data shown in Table 1 was organized in relation to the shape factor, Table 2 and FIG. 6, which will be described later, were obtained. FIG. 6 is a diagram showing the relationship between the shape factor K and the maximum sound pressure level difference ΔL of the Armarod 10 in the embodiment shown in FIG. 2, according to wind speed. In the figure, the solid line a shows the relationship between the shape factor K and the maximum sound pressure level difference ΔL at a wind speed of 15 m/s, and the x and solid line b show the relationship between the shape factor K and the maximum sound pressure level difference ΔL at a wind speed of 25 m/s. Show relationships. From Figure 6, the diameter D (m) of the electric wire and the radius of curvature r
It was confirmed that (m) always influences the maximum sound pressure level difference ΔL only by the curvature radius ratio r/D. It was also confirmed that the opening angle θ (degrees) affects the maximum sound pressure level difference ΔL in the form of logθ. In this case, the influence of the radius of curvature ratio r/D on the maximum sound pressure level difference ΔL is greater than the influence of θ (or logθ), and if the shape factor K is constant, the higher the wind speed, the higher the maximum sound pressure level. It was confirmed that the difference ΔL became lower. Here, unless the maximum sound pressure level difference ΔL takes a negative value, there is no effect of reducing wind noise. Considering Figure 6 based on the above analysis, we get
The shape factor for each wind speed at which the maximum sound pressure level difference is smaller than 0 (that is, negative) is in the range of shape factor K > 3.05 at a wind speed of 15 m/s, and in the range of shape factor K > 3.05 at a wind speed of 25 m/s.
It can be seen that the wind noise reduction effect can be achieved in the range of >2.55. By the way, in general, in an area where the wind speed is low, the value of the maximum sound pressure level itself is lower than the value in an area where the wind speed is high. Taking the above into consideration, the wind speed at which wind noise problems occur significantly is
The diameter D (m) and radius of curvature r ( m) and opening angle θ (degrees), it was found that the maximum sound pressure level could be lowered in relatively high wind speed regions where wind noise problems occur, and the wind noise reduction effect could be achieved. . In addition, by increasing the values of the radius of curvature ratio r/D and the opening angle θ (degrees), the value of the shape coefficient K can be increased, and the low wind noise effect can therefore be further exhibited. can. However, due to the structural design of the jumper wire, the height of the wire 12 and the opening angle θ
Since there are restrictions on the twisting of wires when the angle (degree) is increased, when actually manufacturing Armarod, the radius of curvature ratio r/D≦1/6 and the opening angle θ≦180° are required. This is expected to be a general limit. However, the technical idea of the present invention is not limited to this value. In this case, when the radius of curvature ratio r/D = 1/6 and the opening angle θ = 180°, the shape factor K = 3.92, and the shape factor K>
It satisfies the condition 2.55. That is, the Armarod 10 of the embodiment shown in FIG. 2 can be fully applied to the structural design of an actual Armarod, and the data described above also covers this range. FIG. 7 is an illustrative view of an armarod 20 according to another embodiment of the invention. In the embodiment shown in FIG. 2, the outer corner portion of each of the wires 12 of the Armarod 10 is shaped like an arc with a radius of curvature r, but in this embodiment, one wire 12 is The opening angle (θ ₁ ) of It was formed in In this case, if the opening angle θ = 30°, the angle of the butted part of the two strands will not form an arc, or even if it does, it will be a minute arc that is necessary for manufacturing. The corners of both strands on the adjacent group side are formed into circular arcs with a radius of curvature r. Further, as shown in the figure, when the opening angle θ is 45°, one group of strands 21 is composed of three strands 21a to 21c, and both sides of the central strand 21b in the same group are No arc is formed in the portion adjacent to the central wire 21b, and the corner of one outer circumferential portion of the left and right wires 21a, 21c sandwiching the central wire 21b is formed into an arc shape with a radius of curvature r. 2
form 3. As in this example, the opening angle θ of adjacent grooves
By composing the wire group surrounded by (degrees) with multiple wires, even if the opening angle θ and the length of the wires in the circumferential direction are large, it is easy to twist and manufacture. There are advantages that can be achieved. As described above, the present invention provides an armor rod consisting of a set of wires attached to a jumper wire.
Arc surfaces with a radius of curvature r (m) are formed at the outer corners of adjacent strands of each constant number of strands, and a plurality of grooves are formed by bringing each arc surface into contact with each other, and the radius of curvature r ( m), the diameter D (m) of the jumper wire including Armarod, and the opening angle θ (degrees) of the groove, by selecting the relationship of 10・r/D+logθ>2.55 to significantly reduce the wind noise of the jumper wire. This has the effect of realizing a jumper wire with a lower pitch.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram in which the sound pressure level of wind noise from power transmission lines was measured for each frequency band. FIG. 2 shows a sectional view of the Armarod 10 according to an embodiment of the present invention, and FIG. 3 shows an enlarged sectional view of the divided conductor of the Armarod 10. FIG. 4 is a partially omitted plan view of the jumper wire with the Armarod of the present invention attached. FIG. 5 is a diagram showing the difference in the maximum sound pressure level of wind noise for each frequency band between the conventional power transmission line and the Armarod 10 of this embodiment. FIG. 6 is a diagram showing the relationship between the shape factor K and the maximum sound pressure level difference ΔL of the Armarod 10 of the embodiment shown in FIG. 2A, depending on the wind speed. FIG. 7 is a sectional view of another embodiment of the invention. 10...Armarod, 11...Jampa line, 12
...Bare wire, 13...groove.

Claims (1)

[Scope of Claims] 1. In an armored wire consisting of a set of wires attached to jumper wires of an overhead power transmission line, the outer surface of the wires is concentric with the outer circumferential arc surface of the jumper wire in a direction perpendicular to its length direction. The wire is formed into an arcuate surface, giving a spiral twist to each strand, and the inner diameter as seen from the end face is formed to be slightly smaller than the outer diameter of the jumper wire. A circular arc surface with a radius of curvature smaller than the above circular arc surface is formed at the outer corner of each strand, and the arc surfaces are brought into contact with each other to gather each strand to form a groove in the length direction. Let θ be the angle with respect to the center of the jumper wires, r be the radius of curvature of the outer corner of the wire forming the groove, and D be the diameter of the jumper wire including armarod, then these are selected to have a relationship of 10・r/D+logθ>2.55. Low wind sound armored.