JPS6118403B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for installing a new cut-in tower between existing towers on which power transmission lines have been installed, and installing a prefabricated overhead line between the existing tower and the cut-in tower using the existing power transmission line. The present invention relates to a prefabricated overhead line method using existing power transmission lines that makes it possible to install overhead lines without lowering the overhead lines.

In the span of an existing tower, it may be necessary to install a new tower near the center of the span and use the existing power transmission line to connect overhead lines.

In such cases, it would be complicated to remove the existing transmission line and extend and tie it using conventional methods, and even if prefabricated overhead lines were to be installed, they would have to be lowered to the ground and then measured using precision gauges. Doing so would not only be time-consuming, but could also cause damage to the wires.

The present invention has been made in order to solve these conventional difficulties.In the span of an existing tower, a new cut-in tower is installed near the center of the span, and when carrying out overhead lines using the existing power transmission lines, it is possible to The present invention aims to provide a prefabricated overhead line construction method that makes it possible to install prefabricated overhead lines without lowering power transmission lines to the ground.

That is, the present invention installs a new cut-in tower between existing towers on which power transmission lines have been installed, and when installing prefabricated overhead lines between the existing tower and the cut-in tower using the power transmission line, a temporary mark is placed near the planned cutting position of the power transmission line. At the same time, high-precision surveying equipment will be installed on the ground, or a high-precision tension meter will be installed between the existing power transmission lines and the existing towers, and measurements will be taken between the support points of the existing towers and between the support points of the existing towers. The specifications necessary to determine the actual length of the transmission line between the existing tower support point and the temporary mark, such as the distance between marks, height difference, and wire tension, are measured with high precision, and based on these measurement results. While determining the actual length of the wire between the temporary marks on the existing towers, we also constructed a new cutting-in tower between the existing towers and measured the distance between the existing tower and the supports of the cutting-in tower using high-precision surveying equipment installed on the ground. Based on the results and the specifications measured with high precision between the support points of the existing tower and between the support points of the existing tower and temporary marks, the actual length of the transmission line to be constructed between the support points of the existing tower and the cut-in tower is determined. The present invention relates to a prefabricated overhead wire using an existing power transmission line, characterized in that the power transmission line is cut by determining the actual length of the wire and measuring the cutting position of the power transmission line from the temporary mark position based on the actual length of the wire.

The details of the present invention will be explained below with reference to the drawings.

FIG. 1 is an explanatory diagram of the method of the present invention, and FIG. 2 is a diagram of the principle of the method of the present invention.

In Fig. 1, 1 and 1' indicate the existing steel towers, and the insulators 2 and 2 of these existing steel towers 1 and 1'
A power transmission line 3 is installed between 2'. Install a new cut-in tower 4 between the existing towers 1 and 1', and connect the existing tower 1.
When using the power transmission line 3 to connect the cable between the cable tower 4 and the cut-in tower 4, and between the cut-in tower 4 and the existing tower 1',
In the present invention, first, the planned cutting position of the power transmission line 3 is determined by a desk calculation, and a spacecraft or the like is used to move onto the power transmission line 3, and a temporary marking 5 is applied to the corresponding position. The temporary marking 5 is made by wrapping two colored vinyl tapes against each other or by overlapping them and using the point of discoloration as the measurement point.

Next, the light wave rangefinder body 6 is installed near the center of the span of the existing steel towers 1, 1', and the mirror is installed near the center of the span of the existing steel towers 1, 1'.
Install it at the center of the bolt hole where the insulator chain is attached at the tip of the arm 1', and connect it between the light wave rangefinder main body 6 and the mirror (high support point A, low support point B) as shown in Figure 2. The distances l ₁ , l ₂ , elevation angles θ ₁ , θ ₂ and horizontal angle β are measured, and from these measurement results, the horizontal span length S and height difference h can be calculated using equations () and ().
Calculate.

h = h ₁ - h ₂ = l ₁ sin θ ₁ - _{l 2} Sin θ ₂ ... (2) Here, h ₁ and h ₂ are the distance between support points A and B and projection points A' and B' of these support points. It shows the distance.

Next, attach a high-precision tension meter to the tip of the insulator on the center side of the span or use precision surveying equipment to measure the wire sag, and calculate the actual length L of the power transmission line 3 for the entire span as follows. calculate.

Since overhead power transmission lines generally take a catenary curve, the shape of the curve formed by the transmission line is expressed as y=Ccoshx/c+K ₂ (3). Here, C is the ratio of the horizontal tension (T) to the wire unit quantity (W), and K ₂ is the integral constant. Equation (3) is x = at the lowest point of the wire
At O, y=C+K ₂ .

Therefore, the coordinates of the lowest point C of the wire are exactly y=
If selected so that C, then K ₂ = O, so
Equation (3) becomes y=Ccoshx/c (4).

In addition, the general formula for the actual length l of the wire from the lowest point C to any point, and the general formula for the actual length Lo of the wire between supporting points when there is no height difference, are equations (5) and (6), respectively. It is expressed as

l=Csinhx/c...(5) Lo=2CsinhS/2c...(6) Therefore, when there is a difference in height, the actual length L of the wire for the entire span is between the high support point A and the lowest point C. The horizontal distance between the lowest support point B and the lowest point C is n.
Then, it is expressed as L=Csinhm/c+Csinhn/c...(7).

On the other hand, the height difference h between the support points AB is expressed by equation (8).

h=Ccoshm/c-Ccoshn/c...(8) Therefore, by substituting this equation (8) and the above-mentioned equation (6) into equation (7), the actual wire length L of the entire span can be calculated.
is expressed as L=√ ² + ² ...(9).

Here, it is also possible to obtain an approximate value for the actual wire L by setting L≒√ ² + ² , but there is a drawback that such an approximate value of the actual wire length cannot be applied to prefabricated overhead wires that are constructed with a precision of 1/100,000. be.

The details of the above-mentioned catenary type induction type are also described in, for example, ``Sagness of Overhead Power Transmission Lines,'' written by Hideyo Takeshita and published by the Electric Power Company on November 25, 1950.

By the way, the horizontal distances from the high support point A to the measurement point M of the temporary marking 5 and from the low support point B to the measurement point M of the temporary marking 5 can be determined using equations (10) to (13).

α ₁ = cos ^-1 (l ₁ ′ ² + S ² −l ₂ ′ ² /2・l ₁ ′
・S)...(10) α ₂ = cos ^-1 (l ₂ ′ ² +S ² −l ₁ ′ ² /2・l ₂ ′
・S)…(11) A′M′=′・sinβ′/sinα ₁ ………(12) B′M′=′・sin(β−β′)/sinα ₂ ……
(13) However, ′=l ₁ ′・sinα ₁ /sin(α ₁ +
β′).

On the other hand, high support point A and measurement point M of temporary marking 5
The height difference (△H _A ) between the low support point B and the measurement point M of the temporary marking 5 (△H _B ) is the Y coordinate of the high support point A, the measurement point M, and the low support point B. Letting Y _A , Y _M and Y _B be respectively expressed by equations (14) and (15).

△H _A = Y _A − Y _M ……(14) △H _B = Y _B − Y _M ……(15) In addition, Y _A and Y _B in the above formula are replaced by h ₁ and h ₂ in formula (2). Y _M can be obtained by substituting the x-coordinate of the measurement point M, that is, the equation (12), into the equation (4).

Therefore, the actual wire length L between _AM and BM
The actual length of the wire between L _BM is the horizontal distance between AM and L _OA
If the horizontal distance between _M and BM is L _OBM , it can be expressed by equations (16) and (17), respectively, similar to the induction equation of equation (8).

L _AM √ _OAM ² +△ _A ² ...(16) L _BM √ _OBM ² +△ _B ² ...(17) In this way, the actual wire lengths L _AM and L _BM between AM and BM can be determined with high precision. At the same time, an intervening steel tower 4 is constructed between the existing steel towers 1 and 1', and the existing steel towers 1,
1' and the distance between the support points, and the actual wire lengths L _AM and L _B
The actual length L _AM ′ or L _BM ′ of the power transmission line 3 from the high support point A or the low support point B to the position where the temporary marking 5 is applied is determined under the same conditions as those used for calculating _M.
Then, the difference in the actual length of the wire △l=L _AM '-L _A
M or △l=L _BM '-L _BM is the distance from the measurement point M of the temporary marking 5 to the cutting point, so cut the wire at a position △l away from the measurement point M of the temporary marking 5, and If it is clamped and compressed using the method, it can be directly installed on the interruption tower 4.

As is clear from the above explanation, according to the present invention, high-precision (1/10 ⁴ ) measurement of electric wires is carried out in the overhead line state, which eliminates the need to lower the transmission lines to the ground and measure them. This makes it possible to save labor and shorten the construction period, and also avoids damage when lowering the wires to the ground.

Note that the method of the present invention is applicable to all cases where existing power transmission lines are reused as they are to construct prefabricated overhead lines, regardless of wire size or span length.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the prefabricated overhead wire of the present invention;
The figure shows the principle. 1, 1'...Existing steel tower, 2, 2'...Insulator chain, 3
...Power lines, 4...Interrupting steel towers.

Claims (1)

[Claims] 1. When constructing a new cut-in tower between existing towers on which transmission lines have been erected, and installing prefabricated overhead lines between the existing tower and the cut-in tower using the above-mentioned transmission line, a temporary mark is placed near the planned cutting position of the above-mentioned power transmission line. At the same time, high-precision surveying equipment will be installed on the ground, or a high-precision tension meter will be installed between the existing power transmission lines and the existing towers to measure the distance between the support points of the existing towers and between the support points of the existing towers and temporary marks. The specifications necessary to determine the actual length of the transmission line between the support point of the existing tower and the temporary mark, such as distance, height difference, and wire tension, are measured with high accuracy, and based on these measurement results, the specifications of the existing tower and wire tension are measured. While finding the actual length of the wire between the temporary marks, we installed a new cut-in steel tower between the existing steel towers, measured the distance between the existing tower and the support point of the cut-in tower using high-precision surveying equipment installed on the ground, and compared this measurement result with Based on the specifications measured with high precision between the support points of the existing tower and between the support points of the existing tower and temporary marks, calculate the actual length of the transmission line to be constructed between the support points of the existing tower and the cut-in tower. A prefabricated overhead line method using an existing power transmission line, characterized in that the power transmission line is cut by measuring the cutting position of the power transmission line from the temporary mark position based on the actual length of the power transmission line.