JPH1032920A - Connection box for power cable - Google Patents

Abstract

(57) [Problem] To provide a connection box for a power cable improved so that a bell mouth does not move toward the inside of the connection box; SOLUTION: A bell-mouth has a large-diameter part whose inner diameter of a conductor-exposed side end is increased by several mm over several centimeters, and a step is provided between the large-diameter part and a relatively small inner diameter part, thereby forming a lower winding insulation. Oil-impregnated paper is wound around the inside diameter of the large diameter part of the bell mouth and the smaller inside diameter part, respectively,
The step portion of the bell mouth was configured to be prevented from being caught by the lower wound insulating oil-immersed paper and moving the bell mouth to the side where the cable conductor is exposed. It is preferable to improve the adhesion between the insulating oil-impregnated paper and the bell-mouthed step by making the ridge angle between the stepped part, the large-diameter part, and the relatively small inner diameter part an obtuse angle and tapering.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power cable connection box in which the inside of the connection box is filled with insulating oil.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional connection box for a power cable such as an oil-proof connection box for an OF cable has a stop unit 2 and a conductor connection pipe in a copper pipe (connection box body) 1 as shown in FIG. 3, a bell mouth 4, an insulating oil-immersed paper 5, a tin-plated soft copper wire 6, and the like. Figure 4 shows Bellmouth 4
FIG. 5 specifically shows a bellmouth in the construction of the insulating oil-immersed paper 5.

A method of installing the above-mentioned oil-tight junction box for an OF cable will be described. First, the cable 10 is subjected to a terminal treatment for exposing a predetermined length of the cable insulator by stripping the cable, and then the copper tube 1 Pass the stop unit 2 and the bell mouth 4 on the cable 10,
The conductor of the cable is connected by the conductor connection tube 3. afterwards,
The stop unit 2 is set at a predetermined position so as to contact the conductor connection pipe 3.

Thereafter, as shown in FIG. 4, an insulating oil-immersed paper 5 is wound around the exposed surface of the cable insulator until the inner diameter of the bell mouth 4 is reached. Thereafter, the bell mouth 4 is set at a predetermined position on the insulating oil-immersed paper 5. At this time, the outer diameter of the insulating oil-immersed paper 5 and the inner diameter of the bell mouth 4 are made substantially the same, and the bell mouth 4 is pushed in from the outside of the connection box so as not to move to a predetermined position.

Thereafter, the tin-plated annealed copper wire 6 is wound in the circumferential direction from the rising portion of the insulating oil-immersed paper 5 to the bell mouth 4 so that the insulating oil-immersed paper 5 and the bell mouth 4 do not move. Hold it down. Then, copper tube 1
Is attached to a predetermined size, lead work 9 is performed on both ends, and an anticorrosion tape 8 is wound around the outside to seal.

The bell mouth 4 serves to reduce the electric field in the junction box, and its set position is particularly important in determining the performance of the junction box.

[0007]

According to the prior art described above; according to the junction box shown in FIGS. 3 to 5, the bell mouth 4 is tightly fixed by the diameter difference from the insulating oil-immersed paper 5, and the tin-plated soft copper wire is used. The connection box is fixed by winding it tightly from the end side of the connection box. However, even if the connection box is installed on a bridge, for example, and vibration is constantly applied, There is a possibility that the bell mouse 4 moves (moves as indicated by the arrow in FIG. 4) due to the vibration. With respect to the bell mouth 4, the tin-plated annealed copper wire 5 is tightly wound up toward the outside of the connection box, so that the bell mouth 4 is mechanically fixed and does not move, but the inside, that is, toward the conductor exposed side. The possibility arises because there is nothing mechanically fixed.

Therefore, the problems to be solved by the present invention (objects)
An object of the present invention is to provide a power cable connection box improved so that the bell mouth does not move toward the inside of the connection box;

[0009]

According to the present invention, there is provided a connection box for a power cable, in which a lower wound insulating oil-impregnated paper is wound on a stripped cable insulator and an internal electric field is alleviated on the lower wound insulating oil-impregnated paper. In the power cable connection box in which a bell mouth is set, the bell mouth has a large-diameter portion in which the inside diameter of the conductor-exposed side end is increased by several mm over several cm, and the inside diameter is relatively small. A step is provided between the bell-mouth and the lower-winding insulating oil-impregnated paper is wound around the large-diameter portion of the bell mouth and the inner diameter of the smaller-diameter portion, respectively. The bell mouth is configured so as not to be caught by the insulating oil-immersed paper and to move to the side where the cable conductor is exposed.

It is preferable that the stepped portion and the large-diameter portion and the relatively small inner diameter portion are tapered with an obtuse angle.

[0011]

FIG. 1 shows an embodiment of the present invention.
The main part of the connection box for electric power cables, which shows a combination structure of a bell mouth and insulating oil-impregnated paper on a cable insulator. FIG. 2 shows a cross-sectional structure of the bell mouth in the above embodiment. In this embodiment, the conductor is exposed on the inner diameter portion of the bell mouth 4 '(left side in FIG. 1).
As shown in FIG. 2, the length of about 30 mm from the end of the large-diameter portion is processed into a large-diameter portion 41 by making the diameter approximately 1 mm larger. And a step 43 is provided. The step portion 43 is tapered with an obtuse angle between the ridge angle with the large diameter portion 41 and the ridge angle with the smaller inner diameter portion.

In the case of the insulating oil-impregnated paper 5 'wound on the cable 10 (insulator), two steps, large and small, corresponding to the large diameter portion 41 of the bell mouth 4' and the smaller diameter portion 42 of the bell mouth 4 '. The outer diameter is adjusted so that the outer diameter of is obtained.

The bell mouth 4 'shaped as described above is inserted into the insulating oil-immersed paper 5',
The step 43 of the bell mouth is caught by the insulating oil-immersed paper,
The mouse 4 'to be stretched does not move to the side where the cable conductor is exposed.

A preferred construction procedure of the power cable connection box having the above-described configuration will be described. First, the procedure is the same as that of FIG. 3 until the cable conductor is connected and the stop unit is set at a predetermined position. . Thereafter, the insulating oil-immersed paper 5 ′ is wound on the insulator surface of the cable 10 until the inside diameter of the large-diameter portion 41 of the bell mouth processed as described above is reached. At this time, it is confirmed that the large diameter portion 41 of the bell mouth is tightly fixed to the outer diameter of the insulating oil-immersed paper. Thereafter, the insulating oil-immersed paper 5 ′ is peeled off from a predetermined position near the cable main body side in such a manner that about four insulating papers are aligned with the relative small diameter portion 42 of the bell mouth. Thereafter, the bell mouth 4 'is pushed in from the outside of the connection portion toward the exposed conductor. When the bell mouth 4 'is pushed to the position where the insulating oil-immersed paper 5' is peeled off in a stepped manner, the bell mouth 4 'comes into contact with the step 43 of the bell mouth and is fixed. Subsequent attachment of the tin-plated annealed copper wire 6 is conventional;

4 and 5, the pull-out force of the bell mouth in the direction in which the conductor was exposed was measured.
It was confirmed that it had twice the pulling force.

The reason why the large-diameter portion of the bell mouth 4 'is made larger by 1 mm than the relatively small inner diameter portion 42 is to suppress a decrease in electrical performance such as entrapment of a void as much as possible. This is because it has been confirmed that even at the step, the strength of the pull-out force is sufficiently increased as described above.

The above-mentioned embodiment aims at improving the anti-vibration performance with respect to the oil-tight junction box; FIG. 3, but not only that, but also the upward movement due to the buoyancy of the bell mouth in the terminal junction box. It is also effective for the purpose of preventing movement.

[0018]

According to the present invention as described above, the bell mouth is improved so as not to move toward the inside of the connection box;
The intended task (purpose) of providing a connection box for power cables can be achieved, and stable electric performance can be maintained even when installed on a bridge, which is of great practical value. .

[Brief description of the drawings]

FIG. 1 is a partially cutaway longitudinal sectional view showing a combined structure of a bell mouth and an insulating oil-impregnated paper on a cable insulator according to an embodiment of the present invention.

FIG. 2 is a partially cutaway longitudinal sectional view of a bell mouth according to the embodiment of the present invention.

FIG. 3 is a front view showing a semi-longitudinal section of a power cable;

FIG. 4 is a half cut-away longitudinal sectional view showing a combination structure of a bell mouth and insulating oil-impregnated paper on a cable insulator and a problem in a conventional example.

FIG. 5 is a half cutaway longitudinal sectional view of a bell mouth according to a conventional example.

[Explanation of symbols]

 4 'Bell mouth 41 Large diameter part 42 Relatively small inner diameter part 43 Step part 5' Insulated oil-immersion paper 6 Tin-plated soft copper wire

Claims (2)

[Claims] A power cable connection box comprising: a lower wound insulating oil-impregnated paper wound around a bare cable insulator; and a bell mouth for reducing an internal electric field is set on the lower wound insulating oil-impregnated paper. The bell mouth has a large-diameter portion in which the inner diameter of the conductor-exposed side end is increased by several mm over several cm, and a step is formed between the large-diameter portion and a relatively small inner diameter portion. The paper is wound around the large-diameter portion of the bell mouth and the inner diameter portion of the smaller-diameter portion, respectively, and the step portion of the bell mouth is caught by the lower winding insulating oil-immersed paper, and the bell mouth moves to the side where the cable conductor is exposed. A junction box for power cables that is configured not to be used. 2. The junction box for a power cable according to claim 1, wherein a ridge angle between the step portion and the large diameter portion and the relatively small inner diameter portion is tapered with an obtuse angle.