JPH05284630A - Cable connector and its connection method - Google Patents

Abstract

PURPOSE:To shorten the term of cable connection work by using a connection box which has an expansible/contractible part expanding and contracting in the longitudinal direction of a cable. CONSTITUTION:For a cable connection, a connection box 13, which has a bellowshaped expansible/contractible part 13A expanding and contracting in the longitudinal direction of a cable 1, is used. The cable 1 is connected to the bushings 14 for connection arranged at both ends of the connection box 13. Since the fellow bushings 14 for connection are electrically connected with each other by a flexible conductor 17, the connection box 13 expands or contracts freely in the longitudinal direction of the cable, at the section of the expansible and contractible part 13A. And, this is supported movably by a supporting member 20 such as a wheel 18, a rail 19, etc., whereby the free expansion and contraction of the connection box 13 is allowed. Hereby, the expansion and contraction in the longitudinal direction of the cable 1 are absorbed by the expansive and contractive motion of the connection box 13 itself, so the term of the cable connection work can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable connecting portion having a structure for absorbing thermal expansion and contraction of a cable due to a transmission current and a connecting method.

[0002]

2. Description of the Related Art A power cable generates heat due to a transmission current and expands and contracts due to temperature changes. Therefore, when installing a cable, it is necessary to take measures to absorb this thermal expansion and contraction. FIG. 2 shows a diagram for explaining such a conventional thermal expansion and contraction countermeasure for a cable, (a) is a diagram for explaining the snake laying operation principle, (b) is a plan view showing a connection box and an offset state,
(C) is a front view of a cable bender.

As shown in FIG. 1A, the cable 1 is
So-called snakes are laid so that the heat expansion and contraction can be absorbed. In this example, when the cable 1 is fixed by the cleat 2 at regular intervals and installed in the state shown by the solid line, as shown by the broken line due to thermal expansion and contraction, it is perpendicular to the arrow M in the figure, that is, the installation direction. Exercise in any direction. As a result, the extension of the cable 1 in the longitudinal direction is absorbed as a movement in the width direction, and the concentration of force on the connecting portion is prevented.

When the connection box 3 is arranged in a manhole or the like as shown in (b), offset portions 1A are provided on the cable 1 at both ends thereof. That is, the offset portion 1A is
Just as in the case of snake laying, the cable 1 is bent, and when thermal expansion and contraction of the cable 1 is about to be applied to this connection box 3, slide the connection box 3 in the direction of arrow M, that is, in the direction perpendicular to the cable laying direction. Thermal expansion and contraction are absorbed. As a result, no excessive force is applied to the junction box 3.

When the snake is installed as described above or when the cable 1 is offset, the cable 1 must be bent to have a constant curvature. Power cables are usually very stiff and require very great force to bend them. Therefore, the cable bender 4 as shown in FIG. 2B is used. The cable bender 4 includes a hydraulic cylinder 5, a push rod 6 and two arms 8, and a holding plate 7 attached to the tip of the push rod 6 and a holding plate 9 provided at the tips of the pair of arms 8. The cable 1 is sandwiched by and the push rod 6 is advanced in the arrow P direction to bend the cable 1 to an appropriate curvature. Conventionally, by the above method,
Measures were taken to absorb the heat expansion and contraction of the cable.

[0006]

By the way, the work for laying the snake and offsetting the cable as described above is called snake picking work. This work is performed manually after the cable has been drawn into a cavern or the like. Will be done by Therefore, the cable laying work takes a long time, which hinders shortening of the construction period and cost reduction. The present invention has been made in view of the above points, and an object of the present invention is to provide a cable connecting portion and a connecting method capable of reducing the load of laying work by omitting the snake collecting work as much as possible. ..

[0007]

A cable connecting portion of the present invention comprises a pair of connecting bushings for mounting cable ends, and a connecting box for accommodating the connecting bushings on both sides of an expandable portion. A flexible conductor that electrically connects the connection terminals of the connection bushing to each other near the expandable portion of the connection box; and a support member that movably supports the connection box that expands and contracts due to thermal expansion and contraction of the cable. It is a feature. Further, the connection method of the present invention is characterized in that the expansion / contraction motion in the cable longitudinal direction caused by the temperature change is absorbed by imparting elasticity to the cable connection portion itself.

[0008]

In this cable connection part, a connection box having an expandable part that expands and contracts in the longitudinal direction of the cable is used.
The cables are connected to connecting bushings located on both sides of the connection box. Since the connecting bushings are electrically connected to each other by the flexible conductor, the connection box freely expands and contracts in the cable longitudinal direction at the expandable part. This is movably supported by wheels and rails, allowing free expansion and contraction of the connection box. Alternatively, a method of absorbing thermal expansion and contraction by bending the cable connection portion or the like may be used. As a result, the expansion and contraction of the cable in the longitudinal direction is absorbed by the expansion and contraction movement of the connection box itself, so that there is no need to offset the cable, and cable connection work is shortened.

[0009]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a vertical sectional view showing an embodiment of a cable connecting portion of the present invention. In the figure, the cable 1 is linearly connected inside the connection box 13. Connection bushings 14 are attached to both sides of the connection box 13. The end 12 of the cable 1 is attached to this connecting bushing 14. The connection box 13 is formed of a metal box or the like, and the connection bushing 14 is formed of epoxy resin or the like. The terminal 12 of the cable 1 has a well-known prefabricated plug-in connection structure. Here, a so-called bellows-shaped expandable portion 13A is provided at the center of the connection box 13. That is, the connection box 13 has a structure capable of expanding and contracting in the longitudinal direction at the part of the expandable part 13A. The connection bushing 14 is housed in the connection box 13 so as to be attached to both sides of the expandable portion 13A with the expandable portion 13A interposed therebetween.

A connecting terminal 16 connected to the conductor of the cable 1 and the inside of the connecting bushing 14 is drawn out from the connecting bushing 14, and a pair of connecting terminals 16 facing each other are electrically connected to each other by a flexible conductor 17. There is. A shield ring 15 is attached in order to reduce the electrical stress in the peripheral portion of the connection terminal 16 and surrounds the connection terminal 16. As the flexible conductor 17, for example, a flexible copper stranded wire which has been conventionally used for connection between bus bars is suitable. In addition,
The inside of the connection box 13 is filled with an insulating gas or insulating oil in order to improve the electrical insulation. on the other hand,
An appropriate number of wheels 18 are attached to the lower surface of the connection box 13, and the wheels 18 movably support the connection box 13 on a rail 19 so as to be slidable along the longitudinal direction of the cable 1. .. The wheels 18 and the rails 19 are called support members 20 in the present invention.

The cable connecting portion of the present invention having the above construction operates as follows. That is, the cable 1 does not need to have a particularly large offset as in the conventional cable connecting portion. The cable 1 can be connected linearly to the connection box 13. When the cable 1 expands and contracts due to heat, a force in the cable longitudinal direction is applied to the connection box 13. In this case, the expandable part 13A of the connection box 13 expands and contracts, and the flexible conductor 17 is also bent and extended in accordance with the expansion and contraction. At this time, the connection box 13 is supported by the wheels 18 and freely extends and contracts on the rails 19. As a result, the thermal expansion and contraction of the cable 1 is absorbed by the portion of the connection box 13, and no undue force is applied to other portions. Here, if the expansion and contraction absorption amount of the connection box 13 is set to be sufficiently large, not only the offset of the cable 1 but also a part of the snake laying portion can be omitted. That is, the snake collecting work can be largely omitted, and the construction period can be shortened.

The present invention is not limited to the above embodiments. In the above embodiment, the connection bushing 1 of the connection box 13 is connected.
Although the connection between the cable 4 and the cable 1 has been described as a prefabricated plug-in connection method, this connection can use various structures conventionally used for electrical connection between the cable and the device. In addition, the connection box 13 is provided with an expandable portion 13A capable of expanding and contracting while maintaining airtightness with respect to a case that is conventionally used in a gas insulation device or the like. The structure of the expandable portion 13A in this case is not necessarily a bellows-shaped structure, but may be, for example, a cylinder-shaped structure. The support member 20 may have any structure as long as it has a support structure that allows the expansion and contraction of the connection box 13 freely, for example, the connection box 1
A structure in which 3 is suspended may be used. Further, the method of the present invention may be any method as long as the expansion / contraction motion in the cable longitudinal direction caused by the temperature change can be absorbed by imparting elasticity to the cable connection portion itself. For example, a method of expanding and contracting by bending the cable connecting portion may be adopted.

[0013]

According to the cable connecting portion of the present invention described above, a pair of connecting bushings for mounting cable ends are arranged in the connecting box with the expandable portion interposed therebetween, and the terminals of the connecting bushing are mutually flexible. Since the conductor is electrically connected to movably support the connection box, the thermal expansion and contraction of the cable is absorbed in the connection box. As a result, the snake picking work for offsetting, laying the snake, or the like on the cable can be partially or largely omitted. Therefore, the construction period and the laying cost can be reduced by the connecting portion and the connecting method as in the present invention.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a cable connecting portion of the present invention.

FIG. 2 is a diagram for explaining a heat expansion and contraction absorption countermeasure of a conventional general cable, (a) is an explanatory diagram of a snake laying operation principle, and (b)
Is a plan view showing a state of a connection box and an offset, and (c) is a front view of a cable bender.

[Explanation of symbols]

 1 cable 13 connection box 13A expandable part 14 connection bushing 16 connection terminal 17 flexible conductor 18 wheel 19 rail 20 support member

Claims (2)

[Claims] 1. A pair of connection bushings for mounting cable ends, a connection box for accommodating the connection bushings on both sides of an expandable portion, and the connection box near the expandable portion of the connection box. A cable connecting part comprising: a flexible conductor electrically connecting the connection terminals of the bushing to each other; and a support member that movably supports the connection box that expands and contracts due to thermal expansion and contraction of the cable. 2. A method of connecting a cable, wherein expansion and contraction movement in the cable longitudinal direction caused by temperature change is absorbed by imparting elasticity to the cable connection portion itself.