JPH061932B2 - 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 line method that exhibits excellent effects when overhead lines are installed between steel towers.

[Conventional technology and problems]

When an overhead power transmission line is to be installed, first, a steel tower is constructed, an electric wire is extended between the steel towers, and the overhead wire tension is maintained so as to have a required degree of slackness, and the steel tower is held or suspended from the steel tower arm.

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 an increase in the 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 rivers, ships with high masts may sail directly under the power lines, and if the sag of the ultra-high voltage power lines decreases, the insulation distance between them may be narrowed. , Very dangerous. For this reason, conventionally, in the above-mentioned overhead line section, after extending the transmission line, a work of temporarily tensioning the electric wires by applying a tension exceeding the overhead line tension between the steel towers has been performed.
Currently, steel core aluminum stranded wire is mainly used for electric wires used as high-voltage power transmission lines, but in order to form the sufficient overhead wire sag in the long span, the overhead wire is considerably larger than the normal span. You must give it tension. On this occasion,
Although 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,
Since the aluminum stranded wire that constitutes the conductive member is significantly inferior in strength to the steel core, which is the constituent material of the tension member, it can withstand a large overhead wire tension to secure the slack between the long diameters. It is not obtained 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.

For this reason, excess tension exceeding the overhead wire tension is applied to the wire immediately after the wire is stretched, and the so-called pre-stretch that causes plastic deformation elongation is generated in advance in the aluminum stranded wire portion. The purpose of the excessive tension load work immediately after the wire drawing is to prevent the relaxation of the slack due to the creep elongation while preventing the tension from being shared by the twisted wire portion.

Conventionally, this over-tensioning work involves fixing the strongly pulled wire to the insulator support bracket at the end of the tower arm using a cam along or turnbuckle, and leaving it for the required time to allow the aluminum stranded wire to undergo sufficient plastic deformation. It was done by waiting for the growth to occur. However, this work is performed using a practical steel tower, and the strength of the steel tower is limited in terms of design economy, and it is not possible to apply excessive tension that exceeds the design strength. In addition, all work is done in high places on steel towers, and high tension load work in such high places with poor scaffolding is extremely dangerous, which requires excessive allowances for personnel and tools, In addition to many problems in terms of workability, workability, and economical efficiency, there is a problem in efficiency because of the limitation of the load tension.

[Object of the Invention] The present invention solves the problems of the prior art as described above, and easily and safely prestretches an electric wire to prevent a decrease in sag in a long-span transmission line, and is extremely efficient. The present invention aims to provide a method of connecting a long-span transmission line that can be applied well.

[Summary of the Invention] That is, according to the present invention,
The basic structure is to perform it on the ground before the line is drawn, rather than immediately after the line is drawn between the steel towers as in the past. By utilizing this to enable closed loop wire extension, it is possible to ensure high efficiency and sufficient pre-stretching of electric wires and to ensure economic efficiency and safety.

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

1 to 3 show the transmission line 10 by the overhead line method according to the present invention.
FIG. 2 is an explanatory view for restraining the situation of performing a long-distance crossover wire, and FIG. 2 is a plan view of FIG.

Long span towers T ₁ and T ₂ are constructed on both banks of a distance L that crosses the strait or the river, and large trolleys 1 and 1 ′ are arranged behind them, and the large trolleys 1 and 1 ′ are the stop shafts. Two
It is supported by 2 '. Here, the heavy-duty wagon 1 is an electric wire 10
In addition to being used for extending the wire, it is also used for giving the pre-stretch to the electric wire 10. That is, the yard A provided at the rear of the steel tower T ₁ is the pre-stretching yard, and the large vault 1 has the fixed shaft 7 provided in the vicinity of the steel tower T _{1 for} the electric wire 10 to be extended to the long distance L. It is installed as shown in the figure behind the position of about half the length of the overhead wire, and the electric wire 10 is engaged with the metal groove of the heavy-duty railcar, and the electric wire 10 is almost U-shaped as shown in the plan view of FIG. It is formed.

A temporary clamp 5 is crimped to both ends of the U-shaped electric wire 10, and a connecting wire 7a and a wire 11 to be connected to the fixed shaft 7 can be connected to the connecting hole of the temporary 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 the pulley and the stop shaft 2, and a winding wire 3a of the pulley 3 is wound by a winch 4 so that the heavy wheel & pinion 1 is fixed to the temporary clamp of the electric wire 10. 5 is configured to be crimped and movable in the direction opposite to the terminal portion side connected to the fixed shaft 7, whereby a 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 the overhead wire length.

As described 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 aluminum stranded wire. , Give a pre-stretch.

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 compressed cmdlet 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 clamps 5 crimped to the 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 you rotate like, the wire 10 and the wire 11
And are switched between the towers T ₁ and T ₂ , and the electric wire 1
0 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. Since the electric wire 10 is pre-stretched as described above and the aluminum stranded wire is plastically stretched, the steel core having a high strength shares all the tension of the overhead wire after the overhead wire. Therefore, even if a large overhead line 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. .

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 also be applied to the wire extension other than the loop wire extension, and by pre-stretching by temporarily installing a tension load yard, the present invention can be applied to the wire extension by the wire extension wheel without depending on the heavy-duty wheel. It can be applied to the other. Also, 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, the pre-stretching required for the long-span overhead wire is performed on the ground, so that the following various advantages can be produced.

(1) It is possible to apply necessary and sufficient tension to the electric wire without being restricted by the strength of the steel tower.

(2) By pre-stretching with high tension,
The work time required for pre-stretching can be greatly reduced.

(3) Since the work on the steel tower is changed to the work on the ground, safety, workability, and economic efficiency can be significantly improved.

(4) Since pre-stretching is performed in the temporary yard in front of the main line, it is easy to coordinate the process with the management authorities of rivers, ports, etc. for the work of the overhead line, and the occupancy period of the sky works can be shortened, so the navigation Interference can be minimized.

[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 FIG. 2 is a plan view of FIG. 1, 1: Large wheel, 2: Stop shaft, 3: Pulley, 5: Temporary clamp, 7: Fixed shaft, 9: Winch for wire drawing, 10: Electric wire, 11: Wire for wire drawing.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-57-106313 (JP, A) JP-B 57-14081 (JP, B2) JP-B 53-23018 (JP, B2)

Claims (2)

[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 extension loop, temporarily fix both ends of the electric wire and form a U-shaped electric wire in a direction opposite to the temporarily fixed end of the electric wire. By moving the wire, overhead wire tension is applied to the wire to cause permanent elongation in the aluminum wire part of the wire consisting of the steel core and the aluminum wire, and then the loop is rotated in one direction to transfer the wire between the tower diameters. An extension method for long-span transmission lines in which the wires are stretched and then extended to the sag. 2. The overhead line method according to claim 1, wherein the overhead line location is a strait crossing or a river crossing.