JPH06351143A - Ground fault prevention method for cable offset portion - Google Patents

Abstract

PURPOSE:To effectively prevent the accident of ground fault by making the field work easier by providing cut holes on the surface of a rubber hose at certain intervals for pressure relief and placing an offset portion of electric power cable in the incombustible rubber hose having a reinforcing layer to give flexibility, incombustibility and fire retardancy. CONSTITUTION:Power cable 1, 1' to be laid in a tunnel B and C at the left and right sides are housed in disaster prevention troughs 7, 7'. An offset portion 3 is formed to the cable 1' within a manhole A and is connected to a cable 1 at the connecting portion 2. At the offset portion 3, a rubber hose 20 with a cable 1' inserted is fixed to vertical fittings 8 with a monolithic holding cleat 42. The rubber hose 20 is formed by making cut holes 23 for pressure relief at certain intervals in longitudinal direction, nonmetallic cord such as nylon cord or Vinylon cord is provided internally as a reinforcing layer to give flexibility, incombustibility and pressure resistance, and the rubber hose is connected to flanges 22, 23' at the ends and connected to troughs 31 and 7'. By doing this, the work in the field can be made easier and the accident of ground fault can be easily prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground fault disaster prevention method for power cables, and more particularly to a ground fault disaster prevention method for installing and laying in an offset portion of a power cable for ground fault disaster prevention.

[0002]

2. Description of the Related Art An example of a conventional power cable installed in a cave will be described with reference to the drawings. FIG. 6 shows the installed state of the offset portion of the power cable in the human hole A.
That is, the electric power cable 1 laid in the left cave B is
In the human hole A, the power cable 1 ′ laid in the right side cave C is formed with the offset portion 3 and is connected by the connection portion 2. The connecting portion 2 is fixed by a connecting portion cleat 4 in the human hole portion B. On the other hand, the power cables 1 and 1 ′ in the caveways B and C are housed in the disaster prevention troughs 7 and 7 ′, respectively, and the ends are fixed by the trough cleat 6.
Then, the power cable of the offset portion 3 is fixed to the upright 8 by the cable cleat 5. In this way, the power cable 1 installed in the cave is installed in the general cave B and C, for example, ground fault prevention measures such as being stored in the disaster trough 7, but in the manhole A, the bare cable is installed. Therefore, there is a problem in disaster prevention. In addition, the connection portion 2 in the human hole A
Although the current state is naked, the connection part 2 does not move, so it has been proposed to store it in a trough or cover it with a disaster prevention plate.

[0003]

By the way, the offset portion 3 of the power cable has a complicated shape (three-dimensional bending).
In addition, since the heat generated by energization causes shape deformation due to thermal expansion and contraction, the container becomes too large to be stored in a non-flexible container such as the current disaster prevention trough 7, 7 ',
This is not practical.

The present invention has been made in view of the above circumstances, and is a novel cable offset portion ground fault that can be easily installed, is compact, and has an offset portion that can follow the movement of the power cable well. The purpose is to provide disaster prevention methods.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided a flexible rubber hose which is provided on its side surface with pressure-relief cut openings at intervals.
This is a ground fault prevention method for a cable offset part, which is characterized by including a reinforcing layer so as to have flame resistance and pressure resistance and forming it with a flame-retardant material, and storing the offset part of the power cable in this rubber hose. Further, the present invention is a ground fault prevention method for a cable offset portion, characterized in that the rubber hose is doubled inside and outside, and the cutouts for releasing pressure of the rubber hose inside and outside are provided at different positions.

[0006]

The cable offset portion is housed in a flexible, flame-retardant and pressure-resistant rubber hose, and can follow the heat expansion and contraction of the power cable well. In addition, it has a mechanism that can respond by releasing the pressure at the time of a ground fault and can restore it. And
It can be easily constructed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a ground fault prevention method for a cable offset portion according to the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a rubber hose for ground fault disaster prevention used in this ground fault disaster prevention method. That is, the rubber hose 20 is formed of a flame-retardant material having a reinforcing layer 21 made of a non-metallic cord such as a nylon cord or vinylon cord therein, and a space for inserting the power cable is provided therein. As this rubber material, for example, chlorosulfonated polyethylene, chloroprene rubber and the like are suitable from the viewpoint of flame retardancy and flexibility. This is because when a ground fault occurs in the power cable inserted inside, the local pressure increases and can withstand this.

FIG. 2 shows a side view of the end portion of the rubber hose 20 shown in FIG. That is, the pressure release notches 23 are formed on the side surface of the rubber hose 20 at intervals. This is because when a ground fault occurs in the power cable and the pressure increases, the pressure is released, and after the ground fault, the air flow into the rubber hose is cut off to prevent combustion. This pressure release cutout 23
Are provided on the rubber hose 20 at intervals of 1 to 2 m. A rubber hose end flange 22 is attached to the end portion.

FIG. 3 is a side view showing a laid state of a disaster prevention trough using the rubber hose 20. That is, the power cables 1, 1 ′ laid in the left-side cave B and the right-side cave C are housed and laid in the disaster prevention troughs 7, 7 ′, respectively. In the human hole portion A, a power cable 1 ′ on the right side having an offset portion 3 is connected to the power cable 1 by a connecting portion 2. The connecting portion 2 is housed in the connecting portion trough 31 together with the connecting portion cleat 4 and reinforced for disaster prevention. At this time, the offset portion 3 is covered with the rubber hose 20, and the rubber hose end flange 22 at the left end is covered.
Is connected to the connecting portion trough 31, and the right rubber hose terminal flange 22 'is connected to the trough 7'in the cave C for sealing.

4 (a) and 4 (b) are sectional views of a cleat portion for pressing the power cable 1'and the rubber hose 20 together. That is, the integrated pressing cleat 42 has the rubber hose 20 into which the power cable 1'is inserted from above and below with the bolts 44 and the nuts 45 at both ends of the upper and lower pressing plates 42a and 42b in which a groove 43 larger than the outer circumference of the cable is formed in the cable sandwiching portion. It is screwed in and fixed. At this time, as shown in FIG. 4B, the rubber hose 20 is pressed from above and below, is crushed, and is held in the form of extending left and right. The cleat 42 for integrally pressing the human body is formed in the human hole A.
It is fixed to the inner metal fitting 8 by a well-known fixing means.
Therefore, the power cables 1 and 1'in the sinuses B and C and the manhole A are completely stored in the trough including the offset portion, and the stored power cables 1 and 1'are not deformed due to thermal expansion and contraction. It follows well, and the offset portion is not bulky and can be easily installed.

In the above example, the case where the flange portion is provided at the end portion of the rubber hose for connection has been described, but as a modification, for example, the rubber hose is provided deeper in the trough than the cleat terminal portion of the power cable in the trough. The power cable and the rubber hose may be inserted and restrained together. By doing this, it is not necessary to process the end of the rubber hose,
Even if the length of the offset portion is different, it is possible to easily cope with it.

Further, another embodiment will be described. Figure 3 above
In the example shown in (1), the rubber hose provided in the offset portion of the power cable is single, but as a result of the experiment, the pressure release cutout 2 provided in the rubber hose 20 due to the pressure release in the ground fault accident.
There was a case where 3 did not return to its original shape after the pressure was released due to deformation or local tearing. Therefore, as shown in FIG. 5, a rubber hose 5 that covers the offset portion of the power cable
The inner and outer double covers of 1,52 are provided to further reinforce. The energy at the time of ground fault is the product of current and time. If this energy is large, the rubber hose 51 inside and outside,
By arranging the pressure release cutouts 53 and 54 of 52 so as to be displaced, even if the pressure release cutout 53 of the inner rubber hose 51 does not return to the original state, the pressure release cutout 54 of the outer rubber hose 52 remains the same. It becomes possible to stop the inflow of air and stop the continuation of the combustion of the power cable 1.

[0013]

As described above, according to the ground fault prevention method for the cable offset portion of the present invention, it is possible to follow the movement of the power cable. Be the way.
Further, when it is necessary to fix the power cable, it is possible to easily fix the rubber hose and the power cable integrally. Also, it is possible to set the direction of pressure release at the time of the ground fault to the safest direction as much as possible.

Moreover, when the power cable is an OF cable, oil can be prevented from leaking to the outside. Also, different offset shapes can be connected by combining standard length rubber hoses, and it is possible to cope with this by processing one end at the site or pressing the end with a cleat instead of a flange connection.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a rubber hose used in a ground fault prevention method for a cable offset portion of the present invention,

2 is a side view of the end of FIG. 2,

FIG. 3 is an explanatory view for explaining a state of laying in a manhole showing an embodiment of a ground fault prevention method for a cable offset portion of the present invention;

4 (a) and 4 (b) are cross-sectional views of an integrated pressing cleat for fixing a rubber hose,

FIG. 5 is a partially cutaway side view of a rubber hose showing another embodiment of the ground fault prevention method for a cable offset portion of the present invention,

FIG. 6 is an explanatory diagram for explaining an example of a conventional ground fault prevention method for a cable offset portion, for explaining a laying state in a manhole.

[Explanation of symbols]

 1,1 'Power cable 2 Connection part 3 Offset part 4 Connection part cleat 5 Cable cleat 6 Cleat in trough 7,7' Trough 8 Standing metal fittings 20,51,52 Rubber hose 21 Reinforcing layer 22,22 'Flange part 23,53 , 54 Pressure release notch 31 Connection part trough 42 Integrated pressing cleat 42a, 42b Pressing plate 43 Groove 44 Bolt 45 Nut

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[Procedure amendment]

[Submission date] September 9, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

[0005]

SUMMARY OF THE INVENTION This invention is a flexible rubber hose which is provided at intervals the cutting port of the pressure release on the front surface,
This is a ground fault prevention method for a cable offset part, which is characterized by including a reinforcing layer so as to have flame resistance and pressure resistance and forming it with a flame-retardant material, and storing the offset part of the power cable in this rubber hose. Further, the present invention is a ground fault prevention method for a cable offset portion, characterized in that the rubber hose is doubled inside and outside, and the cutouts for releasing pressure of the rubber hose inside and outside are provided at different positions.

Claims (2)

[Claims] 1. A rubber hose provided with pressure release cutouts on its side surface with a space provided between the rubber hose and a reinforcement layer so as to have flexibility, flame retardancy and pressure resistance, and is formed of a flame retardant material. A ground fault prevention method for a cable offset part, characterized in that the offset part of the power cable is stored in a rubber hose. 2. The ground fault prevention method for a cable offset part according to claim 1, wherein the rubber hose is doubled inside and outside and the cut-out openings for releasing pressure of the rubber hose inside and outside are provided at different positions.