JPH0797886B2 - Overhead method for long-span transmission lines - Google Patents

Description

TECHNICAL FIELD The present invention relates to an overhead power transmission line overhead wire method, and in particular, it is difficult to construct a steel tower in the middle such as across a strait or across a river, and a long span has been achieved. The present invention relates to a novel overhead wire method that exhibits excellent effects when an aluminum covered wire is installed between steel towers.

[Conventional Technology and Problems] When overhead lines are to be installed, first construct a steel tower, extend the wires between the steel towers, and maintain the overhead wire tension so that the required degree of slackness is maintained and hold the steel tower arm. Or hang it up.

The length of the steel tower in a normal transmission line is at most several hundred meters even if it becomes long, and if it is possible to make it longer than that, build another steel tower in the middle so that it will not be too long. It is usually designed.

However, it is difficult to construct a steel tower as desired in a special area for forming a track, such as a strait, a river crossing area, or a mountainous area, which often leads to a long span. If it is a mountainous area, there is usually a considerable distance to the valley and it is unlikely that the sag of the wire will decrease.

However, at the crossing of the straits and the crossing of rivers, ships with high masts may sail directly under the transmission line, and if the sag of the ultra-high voltage transmission line decreases, the insulation distance between them may become narrower. , Very dangerous. For this reason, conventionally, in the above-mentioned overhead line section, after extending the power transmission line, a work of temporarily tensioning the electric wire by applying a tension exceeding the overhead line tension between the steel towers has been performed. Steel core aluminum stranded wire is generally used for electric wires used as ultra-high-voltage power transmission lines, but in order to form the above sufficient overhead wire sag in the above-mentioned longest span, a considerably larger overhead wire than the normal span. You must give it tension. At this time, the aluminum stranded wire and the steel core of the steel core aluminum stranded wire used as an ultra-high voltage power transmission line share the overhead wire tension together, but the aluminum stranded wire forming the conductive member serves as a tension member. Since it is much inferior in strength to the steel core as a constituent material, it cannot withstand a large overhead wire tension for securing the slack in the long axis and creep elongation occurs. The creep elongation of the aluminum stranded wire portion is the largest factor for reducing the sag of the overhead wire.

Therefore, a so-called pre-stretch that causes plastic deformation extension in advance in the aluminum stranded wire portion is performed by applying excessive tension exceeding the overhead wire tension (equal to the tension when the electric wire is laid) to the electric wire immediately after the wire drawing. It has been given that the tension of the aluminum stranded wire is no longer shared under the tension of the overhead wire to prevent the sagging from decreasing due to the creep elongation. It is the purpose of the work.

For example, assuming that the tension in the installed condition is 25t, this tension will apply a prestress of about 50t, which is twice that, but when performing such work, 0t → 25t → Pre-stretch like 50t → 0t and then lay it (0t →
25t).

Figure 4 shows the S / S curve of aluminum during pre-stretching. Here, the point A shows the strain amount corresponding to 50t, and the point B shows the residual strain amount when it is released to 0t thereafter.

In the case of steel core aluminum stranded wire, since the steel wire and aluminum wire are disjointed, when released to 0t, the aluminum wire laughs and becomes a loose stranded wire.

However, in the case of an aluminum covered wire in which steel and aluminum are integrated, as shown in Fig. 5, when released to 0t, a negative tension, that is, a compressive force acts on the aluminum covered part. become.

This is a very serious problem, and when prestretching is applied in this way, high tension between the long diameters may cause too much aluminum stress, and the aluminum coating may be cut off. .

[Object of the Invention] In view of such a situation, the present invention has reviewed a conventional method of prestretching, and provides a method of extending a long-span transmission line including prestretching work without any obstacle to an aluminum steel wire. The purpose is to provide.

[Summary of the Invention] That is, according to the present invention,
The basic structure is to carry out on the ground before the wire extension, and in particular, by using the gold wheel as a tool for that purpose for the subsequent wire extension as it is and performing the closed loop wire extension, the wire tension above The work of laying the electric wire after pre-stretching is performed with the tension applied.

[Examples] Hereinafter, the present invention will be sequentially described based on Examples.

1 to 3 are explanatory views showing a state in which a long-distance crossover of the power transmission line 10 is performed by the overhead wire method according to the present invention, and FIG. 2 is a plan view of FIG.

Long span towers on both banks of distance L across the strait or river
T ₁ and T ₂ were built, and heavy-duty cars 1,1 ′ were set behind them.
Are arranged, and the heavy-duty wheel 1,1 'is supported by the stop shafts 2,2'. Here, the heavy-duty wheel & pinion 1 is used to extend the electric wire 10, and is also used to give the electric wire 10 the pre-stretch. That is, the yard A provided at the rear of the steel tower T ₁ is the pre-stretching yard, and the heavy metal wheel 1 has a fixed shaft 7 provided in the vicinity of the steel tower _{1 for connecting} the electric wire 10 to be extended to the long distance L. Arranged behind the position of about half the overhead line as shown in the figure, the electric wire 10 is engaged in the metal groove of the heavy-duty wheel,
The electric wire 10 is formed in a substantially U shape as seen in the plan view of FIG.

The temporary fixing clamp 5 is crimped to both ends of the U-shaped electric wire 10, and the connecting wire 7a and the wire extension wire 11 to be connected to the fixed shaft 7 can be connected to the connecting hole of the temporary fixing clamp 5. To be done. FIG. 2 shows a situation in which the connecting wire 7a and the wire drawing wire 11 are both connected to the connecting hole of the temporary clamp 5, but during the pre-stretching work, Linking is not always necessary.

Under the electric wire 10, rollers 6 are installed to prevent the electric wire 10 from being scratched or scratched on the ground.
A pulley 3 for applying a tension is installed between and, and the winding wire 3a of the pulley 3 is wound by the winch 4, so that the heavy-duty wheel 1 is crimped to the temporary clamp 5 of the electric wire 10. It is constructed so that it can be moved in the direction opposite to the terminal portion side connected to the fixed shaft 7, whereby the U-shaped arrangement is provided between the fixed shaft 7 and the heavy wheel & pinion 1. It is configured to apply a tension to the electric wire 10 having an overhead wire length.

By the above, the winding wire 3a is wound by the winch 4,
The heavy wheel & pinion 1 is retracted, and a sufficiently large tension exceeding the overhead wire tension is applied to the electric wire 10 to cause sufficient plastic deformation elongation of the electric wire and pre-stretching.

Since the pre-stretching is performed without using a steel tower as in the conventional example and all is performed on the ground before the wire drawing, the work is extremely flexible, and the heavy metal wheel 1, the stop shaft 2, the pulley 3, and the fixed wheel 3 are fixed. Since tools such as the shaft 7 can be easily selected to have sufficient strength as needed, there is no restriction on the tension to be applied for pre-stretching, and the necessary and sufficient tension can be applied. It is safe because it is loaded with tension, and the number of workers required is the minimum required.

Loaded with sufficient tension to the wire 10 as described above, once sufficient pre-stretch is performed, is engaged supported on one of the fortune wheel 1 ', installed on the arm as well as terrestrial towers T ₁ and T ₂ Both ends of the extended wire 11 stretched toward the electric wire 10 side and the temporary clamp 5 crimped to both ends of the electric wire 10 are connected to each other via the gold wheels 8 and 8'provided. Form an extended loop as shown in Fig. 2. Here, the connection between the fixed shaft 7 and the electric wire 10 is released, the tension of the entire loop is adjusted by the pulley 3, and the wire drawing winch 9 is used to move the wire drawing loop as shown in FIG. If it is rotated like this, the electric wire 10 and the extended wire 11 will be connected to the towers T ₁ and T ₂
The wires 10 are replaced with each other and the electric wire 10 is extended. The electric wire 10 thus extended is tightly tensioned to a required overhead wire tension, and is connected and fixed to the insulator string of the steel towers T ₁ and T ₂ to complete the overhead wire.
After the pre-stretching is applied, the wire 10
Is not given a lower tension history than the overhead wire tension. That is, in the above example, 0 → 25t → 50t → 25t
And will never be 0t after 50t. Even if a large overhead wire tension is applied to maintain the slack in the long diameter such as across the strait or across the river, the electric wire 10 hardly causes creep elongation, and the problem of unexpected decrease in the slack is completely solved.

Here, the electric wire 10 is generally a steel-core aluminum stranded wire, but it may be an aluminum-covered wire because the present invention is an invention made for the aluminum-covered wire as described above. Can be said.

In the above, the heavy-duty wheel is a very useful tool for drawing a wire between such long diameters, and it is one of the necessary tools for drawing a wire, and the fact that it was adopted for pre-stretching It should be one of the effects brought about by the invention. All the other tools, such as pulleys and winches, can be fully used for ordinary ones, and it can be said that the effect of the present invention in view of economical efficiency is also noteworthy.

However, the above does not mean to limit the technical idea of the present invention. That is, the present invention can be applied to wire extensions other than the loop wire extension, and if prestretching is performed by hypothesizing the tension load yard separately, the present invention can be applied to wire extensions by wire drawing vehicles without relying on heavy-duty trains. It can be applied to the other. Further, of course, the tension load for pre-stretching does not depend only on the pulley, but it is needless to say that hydraulic pressure or mechanical force such as gears can be applied as necessary.

[Effects of the Invention] As described above in detail, in the present invention, after the pre-stretching necessary for the long-span overhead wire until the installation of the overhead wire is completed, the wire is given a tension equal to or higher than the overhead wire tension.
The reliability of the long span span wire is high, as the woven wire does not break even when using the steel cored aluminum stranded wire as well as the aluminum covered wire.

[Brief description of drawings]

1 to 3 are explanatory views showing a situation in which the overhead wire construction method according to the present invention is being carried out, and FIGS. 4 and 5 are S / A of aluminum.
It is a diagram showing an S curve. 1,1 ': Heavy metal wheel, 2: Stop shaft, 3: Pulley, 5: Temporary fixing clamp, 7: Fixed shaft, 9: Winch for wire drawing, 10: Electric wire, 11: Wire for wire drawing.

Claims (1)

[Claims] 1. Large heavy rail cars are arranged on both sides of the ground of a long span steel tower to be installed, and an electric wire is provided in one of the heavy rail cars of the heavy rail car.
A wire for wire extension is engaged in the groove of the other heavy-duty wheel, and a wire-drawing loop is formed between the heavy-duty wheel by connecting the wire between the heavy-duty wheel and the wire for extension. Before or after forming the wire-drawing loop, the end of the electric wire is temporarily fixed and the electric wire forming the U-shape is engaged in a direction opposite to the temporary fixing end of the electric wire. By moving the wire to a tension exceeding the overhead wire tension to give a pre-stretch, and then by rotating the loop in one direction, the wire is transferred and extended between the tower diameters, and the overhead wire tension is applied to the wire. An overhead wire method for a long-span transmission line, characterized in that the wire is stretched to a predetermined overhead wire sag while applying the above tension.