JPS6353763B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low wind pressure armarod, and particularly to an armarod that is attached to jumper wires of overhead power transmission lines to reduce wind pressure.

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 simply twists and wraps metal wires with a circular cross section around the outer circumference of the jumper wire.
No consideration has been given to exhibiting low wind pressure characteristics. If the overhead power transmission line itself has low wind pressure characteristics, the jumper wire will also have similar characteristics, so there is no need to specially provide the above characteristics with Armarod, but it does not have such characteristics. Jumper wires in existing overhead power transmission lines tend to sway due to wind pressure and cause flashovers, so it is desirable to reduce wind pressure.

By the way, the maximum wind pressure P when the wind hits the jumper wire is expressed by the following equation (1).

P=1/2ρCx V ² (Kg/m ² ) …(1) However, ρ: Air density (Kg・sec ² /m ⁴ ) Cx: Resistance coefficient of wind receiving surface (dimensionless) V: Wind speed (m/m 4 ) sec) The above drag coefficient Cx depends on the Reynolds number R, and the relationship between the two is determined by wind tunnel experiments.

Figure 1 is a graph of the relationship between the Reynolds number R and the drag coefficient Cx for each type of conventional jumper wire, and the curves a and b are for the following samples a and b.
It is a characteristic of

Sample a: A stranded wire with an outer diameter of 116 mm in which the outermost layer is made up of 30 wires with an outer diameter of 10.6 mm. Sample B: A stranded wire with an outer diameter of 116 mm in which the outermost layer is made up of 36 wires with an outer diameter of 8.9 mm. Sample c: Cylindrical cylinder with an outer diameter of 116 mm As shown in curves a and b above, in the case of stranded wire, when the Reynolds number R is small (for example, 2 x 10 ⁴ ), the resistance coefficient Cx is large, and when R is 4 x 10 ⁴ ~ It becomes minimum at 6×10 ⁴ , and Cx becomes almost flat when R is 6×10 ⁴ or more. On the other hand, curve C is for a cylinder (this is the case where the outer periphery of the jumper wire is covered with a pipe,
(or it may be regarded as a pipe-shaped jumper wire), Cx is large in a region where R is small, and Cx decreases rapidly as R becomes large.

Therefore, ideally, in order to make the outer peripheral surface of the jumper wire cylindrical, cover it with a pipe to create a jumper wire with a small Cx.
If R is small, R will be large, and if R is large, the outer diameter D will become larger than necessary, which is not practical, as is clear from the following equation (2).

R=VD/ν...(2) However, D: Outer diameter of the jumper wire including Armarod (m) ν: Air dynamic viscosity coefficient (m ² /sec), standard condition (normally 15℃, 1 atm for track design) It is constant at 1.456×10 ^-5 m ² /sec.

Therefore, it is necessary to attach Armorrod of a specific shape to the jumper wire with an appropriate outer diameter so that the jumper wire exhibits intermediate characteristics between a jumper wire made by twisting ordinary circular cross-section wires and a cylinder or cylinder. It is believed that a jumper wire with a small drag coefficient, that is, a jumper wire with low wind pressure can be obtained.

An object of the present invention is to provide an armor rod that can be attached to a jumper wire to reduce the coefficient of resistance and reduce the load applied to the jumper wire due to wind pressure.

Hereinafter, specific embodiments of the present invention will be described with reference to 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 Figure 3, the outer and inner surfaces are made of jumper wire 1.
It is on a concentric circle with 1, and both sides are jumper wire 1
It has a constant angle θ with respect to the center of 1. 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 as θ=360/n (where n is a positive integer), n strands 1
2 can be densely arranged around the outer periphery of the jumper wire 11. Moreover, the above-mentioned wire 12 is previously formed into a spiral shape as shown in FIG. 4, and its inner diameter is as follows.
Before it is attached to the jumper wire 11, it is formed to be slightly smaller than the outer diameter of the jumper wire 11, and when it is attached to the jumper wire 11, it is tightly wound 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.

FIG. 5 shows the outer diameter D (m) of the jumper wire 11 including the Armarod 10 and the strand 12 when the Armarod 10 is attached to the outer periphery of the jumper wire 11 and the opening angle θ of the groove 13 is constant. This is a graph obtained experimentally of the relationship between the Reynolds number R and the drag coefficient Cx using samples with different ratios to the radius of curvature r (m) of the circular arc surface, that is, the radius of curvature ratio r/D. The angle θ=12°, the value of r/D is shown when the curve d is 17.4/1000, the curve e is 29.1/1000, and the curve f is 34.9/1000.

By the way, when calculating the wind pressure of a power transmission line, a region in which the rate of change in the resistance coefficient Cx is smaller than the change in the Reynolds number R is usually used in consideration of changes in wind speed. Therefore, when selecting the usage range of the curves d, e, and f according to the curvature radius ratio obtained in each experiment, it is determined as follows. That is, a dashed-dotted line x1 connecting the points of each of the curves d, e, and f where the drag coefficient Cx is the minimum value is selected as the region of the minimum value of the Reynolds number R. On the other hand, the minimum value of the Reynolds number is selected within the range of twice the Reynolds number from the minimum value of the Reynolds number, as is well known to line designers. This is because the range is selected to be twice the design wind speed, taking into account that the actual wind speed varies up and down compared to the design wind speed.
Therefore, the Reynolds number used in the design is
From the minimum value area indicated by the one-dot chain line x ¹ to the two-dot chain line
The range of the maximum value area indicated by y ¹ is selected. That is, when the opening angle θ=12°, the Reynolds number R is selected in the range of about 7.1 to about 28×10 ⁴ when the radius of curvature ratio r/D=17.5/1000 to 34.9/1000.

Next, as shown in FIG. 2, the resistance coefficient Cx of the jumper wire 11 equipped with the Armarod 10 of the present invention and the conventional jumper wire shown by curves a and b in FIG. 1 will be compared and studied. For example, in the range of Reynolds number R=7.5 to 20×10 ⁴ , jumper wire 11 equipped with Armarod 10 of the present invention
has a resistance coefficient Cx of 0.4 to 0.6, while that of conventional jumper wire has a resistance coefficient of Cx of 0.9 to 0.95. Therefore, the jumper wire equipped with Armarod 10 of this invention has R=7.5 to 20× compared to the conventional one.
It was found that Cx could be reduced by 0.3 to 0.55 in the range of ¹⁰⁴ . It can be seen that by reducing the drag coefficient Cx in this way, the wind pressure acting on the jumper wire can be reduced in correlation with the ratio by which the drag coefficient Cx can be reduced, and a low wind pressure effect can be obtained.

The jumper line with reduced wind pressure as described above can be expressed quantitatively by a certain shape factor by appropriately selecting the relationship between the radius of curvature ratio r/D and the opening angle θ from various experiments. I can see that. Therefore, below, we will attempt to quantitatively express the low wind pressure jammer line in relation to the shape factor.

Fig. 6A is a diagram in which the minimum value indicated by the dashed line x ¹ and the maximum value indicated by the dashed dotted line y ¹ in Fig. 5 are replaced with the relationship between the Reynolds number R and the radius of curvature ratio r/D. . In FIG. 6A, the Reynolds number R is shown on the horizontal axis on a logarithmic scale, and the drag coefficient Cx is shown on the vertical axis. The dashed-dotted line x ² shown in FIG. 6A plots the radius of curvature ratio r/D to the minimum value of the Reynolds number R for each sample shown by the dashed-dotted line x ¹ in FIG. It connects the dots. In addition, the two-dot chain line ^y2 is the radius of curvature ratio r/D for the maximum value of the Reynolds number R for each sample, which is indicated by the two-dot chain line ^y1 in Figure 5, is plotted on Figure 6A, and each point is connected. It is something.

Similarly, the inventor of the present invention fabricated prototype samples with different opening angles θ and varying the radius of curvature ratio r/D for the same opening angle θ, and based on the experimental values, the Reynolds number R and the radius of curvature ratio r/D. I investigated the relationship with D.

As a result, it was found that the slope was the same as the slope of the dashed-dotted line x ² representing the region of the minimum value of the Reynolds number shown in FIG. 6A, and only the value in the horizontal axis direction changed. As an example, the measured value when θ = 45° is the 6th
Shown in Figure B. From this, it was found that the relationship between the radius of curvature ratio r/D and the Reynolds number R is expressed by a constant function by determining the slope of the dashed-dotted line x ² shown in FIG. 6A.

So, when we calculated the function, we found that it can be expressed as r/D=K ₁ /R (K ₁ = constant), and that the constant K ₁ is expressed as the product of the radius of curvature ratio r/D and the Reynolds number R. . For example, when θ=12°, if we observe the curves d, e, and f of each material for each radius of curvature r/D in Figure 5, we can see that when r/D=17.4/1000, the Reynolds number R is 14
.4 × 10 ⁴ and when r/D = 29.1/1000 the Reynolds number R is 8.6 × 10 ⁴ and when r/D = 34.9/1000 the Reynolds number R is 7.2 × 10 ⁴ . We get K ₁ = 2500. Therefore, the general formula of the curve shown by the dashed line x ² in FIG. 5A is expressed as r/D=2500/R. Similarly, the maximum value of the constant K ₁ shown by the two-dot chain line y ¹ in FIG.
becomes K ₁ =5000. From this, the general formula of the curve indicated by the two-dot chain line y ² in FIG. 5A is r/D=5000/R. From this, when the opening angle θ=12°,
It has been found that the radius of curvature ratio should be selected such that the relationship between the radius of curvature ratio r/D and the Reynolds number R is in the range of r/D = 2500/R to 5000/R.

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 is 24°, the angle of the butted part of the two wires 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 36°, 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 4. In Figure 8, the radius of curvature ratio r/D is constant (r/D = 34.9/1000) in the jumper line of Figure 2.
Reynolds number R when changing the opening angle θ as
FIG. 3 is a diagram showing the relationship between Cx and resistance coefficient Cx. In the figure, curve g shows the case when θ=12°, curve h shows the case when θ=24°, curve i shows the case when θ=36°, and curve j shows the case when θ=45°. . In this case, a line connecting the minimum values of the resistance coefficients of each sample is indicated by a dashed-dotted line ^x3 . Further, a line connecting the maximum values for each sample when a value twice the minimum value of the Reynolds number R is selected as the maximum value is indicated by a two-dot chain line ^y3 .

FIG. 9A is a diagram in which the minimum value indicated by the one-dot chain line x ³ and the maximum value indicated by the two-dot chain line y ³ in FIG. 8 are replaced with the relationship between the Reynolds number R and the opening angle θ. The range that can be effectively used in FIG. 9A is between x ⁴ and y ⁴ . Although various experiments were conducted using samples with varying radius of curvature ratio r/D, these experiments showed that even when the radius of curvature ratio r/D was varied, the relationship between Reynolds number R and opening angle θ remained the same. It turns out that it can be expressed as a straight line and has the same slope.

As an example, the measured values for r/D=29.1/1000 are shown in FIG. 9B, and the measured values for r/D=45.5/1000 are shown in FIG. 9C.

For example, if we calculate the relationship between the opening angle θ and the Reynolds number R from the slope of the dashed-dotted line x ⁴ in Figure 9A, we find that
In the figure, the function of the opening angle θ when the Reynolds number R is selected as the minimum value is θ=113logR×10 ^-5
It is expressed as +28.5. Also, if we calculate the relationship between the opening angle θ and the Reynolds number R from the slope of the two-dot chain line ^y4 , the function of the opening angle θ when the Reynolds number R in Fig. 8 is selected as the maximum value is θ=
It is expressed as 113logR×10 ^-5 −5.2.

From the above explanations and graphs, the range to which Armarod of the present invention is applicable can be calculated using the following formula.

First, the range of the optimal Reynolds number R when the opening angle is constant at θ = 12° and the radius of curvature ratio (r/D) is changed is the range of (3) as explained with reference to Figure 6A. ) expression.

r/D=2500/R to 5000/R...(3) The radius of curvature r is calculated from equation (3) and is expressed by equation (4).

r=D/R (2500-5000) …(4) Substituting R=VD/ν into equation (4), the curvature of the wire is The radius r is expressed by equation (5).

r=(2500-5000)1.456×10 ^-5 /V =0.0364-0.0728/V (5) From the above equation (5), it can be seen that the radius of curvature r is determined only by the design wind speed value.

On the other hand, when the radius of curvature ratio r/D (=34.9/1000) is constant and the opening angle θ is changed, the optimal θ
The relationship between R and Reynolds number R is expressed by equation (6) as described with reference to FIG. 9A.

θ=113logR×10 ⁻⁵ +(28.5 to −5.2) (6) The relational expression of the Reynolds number R is obtained from the equation (6) and is expressed by the equation (7).

The optimal conditions for the curvature radius ratio and the opening angle θ are calculated as follows based on the above equations (5) and (7). That is, the curvature radius ratio r/D when the opening angle θ is constant is inversely proportional to the Reynolds number R, as is clear from equation (3). Therefore, if we take the proportionality constant and K ₁ , the curvature radius ratio r/D becomes as shown in equation (8).

r/D=K ₁ /R...(8) Next, the proportionality constant K ₁ is obtained by substituting R in equation (7) into equation (8) based on the actual measurement result when the radius of curvature ratio r/D is 34.9/1000. is required.

Therefore, when the opening angle θ is given, the optimum radius of curvature r at the design wind speed V falls within the following range.

Accordingly, in order to select the radius of curvature r expressed by equation (10), by determining the design wind speed value and the opening angle θ, it is possible to know the range of the optimum radius of curvature r.

FIG. 10 is a graph showing the relationship between the design wind speed value V and the radius of curvature r. It is clear that the radius of curvature of the Armarod of the present invention can be applied to the shaded area shown.

Therefore, the radius of curvature r that satisfies the above equation (10)
If a plurality of grooves in which two circular arcs of 2 butt against each other are formed with Armarod in the length direction of the outer periphery of the jumper wire, the wind pressure of the jumper wire can be reduced.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between Reynolds number and drag coefficient of a conventional power transmission line. FIG. 2 is a sectional view of a jumper wire equipped with the Armarod of the present invention. FIG. 3 is a cross-sectional view of the Armarod wire. FIG. 4 is a partially omitted plan view of the jumper wire equipped with Armarod. FIG. 5 is a graph showing the relationship between the Reynolds number and the drag coefficient when θ=12° in the power transmission line of FIG. FIG. 6A is a graph showing the relationship between the Reynolds number R and the radius of curvature ratio r/D for the minimum value shown by the dashed line and the maximum value shown by the chain double dot line in FIG. 5. FIG. 6B is a graph showing the optimum Reynolds number range when θ=45°. FIG. 7 is a sectional view of a power transmission line according to another embodiment of the present invention. FIG. 8 is a graph showing the relationship between Reynolds number R and resistance coefficient Cx when the opening angle is changed in the case of r/D=34.9/1000 in the power transmission line of FIG. 9th
Figure A shows the Reynolds number R for the minimum value shown by the dashed line and the maximum value shown by the dashed line in Figure 6.
It is a graph replaced with the relationship between the opening angle θ and the opening angle θ. Figure 9B is r/D=29.1/1000, Figure 9C is r/D=45.5
2 is a graph showing the optimum Reynolds number range in the case of /1000. FIG. 10 is a graph showing an example of the relationship between the radius of curvature and the design wind speed value to which the present invention is applied. 10...Armarod, 11...Jampa line, 12
...Elementary 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 butted against each other to gather each strand to form a groove in the length direction. When the opening angle with respect to the mutual jumper wire center is θ, the radius of curvature of the outer corner of the wire forming the groove is r, and the wind speed is V, these are Low wind pressure Armarod is characterized by the fact that it has been selected to have a certain relationship.