JPH0226180Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a disaster prevention cover for a power cable trough.

Generally, power cables installed in tunnels and the like are housed and installed in a sealed FRP trough to protect the cables and prevent the spread of fire in the event of a ground fault.

By the way, since the above trough has a closed structure,
Rapid internal air expansion caused by an explosion caused by a power cable ground fault can destroy the trough, creating a risk of secondary fires and other major accidents.

In order to avoid such a danger, as shown in Fig. 1, cuts S...S are formed in the wall of the trough T that mainly spread radially, so that the air inside the trough expands and the pressure increases in the event of a ground fault. In this case, the notch is broken with low internal pressure, air and combustion gas are released from the broken part, and then the trough T is self-restored by elasticity, almost sealing the inside of the trough and blocking the inflow of air from the outside. This is to prevent destruction and the spread of fire to cable C.

However, although the notch of such a conventional structure is effective for a ground fault current of about 20 KA, as the line capacity increases and the ground fault current increases to 40 to 60 KA, a large amount of energy is released.
Since damage to the trough becomes a problem, the thickness of the trough itself needs to be increased from the usual 3 to 4 mm to 5 to 6 mm, which has the disadvantage that the pressure relief effect of the notch becomes poor.

In addition, a cover plate made of an elastic material with a cross-shaped cut formed in the window hole formed in the trough is fixed (see Japanese Patent Application Laid-open No. 1983-66211), and a cover plate made of an elastic material that closes the opening as a fluid on-off valve. A system in which the middle part of the valve body is supported by a rigid girder member has been proposed (see Japanese Patent Publication No. 59-6733), but like the system in which radial notches are formed, as the line capacity increases, the released energy decreases. If the amount is too large, the cut portion will not open wide and will not close rapidly after the pressure is released, resulting in poor pressure relief effect of the cut and problems such as destruction of the trough and cable fire spread.

The purpose of this invention is to provide a disaster prevention lid for power cable troughs that can prevent trough destruction and cable fire spread even in the event of ground fault currents of 40 to 60 KA. A cover plate made of an elastic material and having an area larger than the opening area of the window hole is placed over the hole so as to cover the window hole, and the cover plate is inserted across the middle part of the cover plate so that the cover plate can be used in the event of a cable ground fault. A girder member made of an elastic material is stretched in a substantially V-shape and is curved outward in an arc along the trough of the V-shape, and the girder member is fixed to the trough to attach the cover plate to the trough. It is characterized by the fact that it has been installed.

Next, an embodiment of the present invention will be described in detail with reference to the drawings. In FIGS. 2 and 3, A indicates a disaster prevention lid of a power cable trough (hereinafter simply referred to as a trough) 1; For example, a window hole 2 of an arbitrary shape such as a circular, oval, or rectangular shape formed in the upper lid is provided with a lid plate 3 having an area sufficiently larger than the opening area of the window hole 2 and made of an elastic material such as rubber or plastic. The hole 2 is covered so as to be closed, and a band-shaped girder member 4 made of an elastic material such as FRP, rubber, or plastic is inserted from the outside across the middle part, preferably approximately the center part, in the width direction of the trough. The cover plate 3 is fixed to the trough 1 with bolts etc.
is configured to be attached to the trough 1. Girder member 4
There is no need to mechanically connect the cover plate 3 with the cover plate 3,
If necessary, they may be joined using screws, adhesive, etc. In the event of a cable ground fault, the cover plate 3 is moved around the girder member 4 as a fulcrum.
When viewed from the trough width direction, it has a substantially V-shape, and is curved outward in an arc along the trough of the V-shape.

As shown in FIG. 4, the girder member 4 may be fixed to the trough 1 and support the cover plate 3 by wrapping around the outer periphery of the trough 1 and fastening both ends to each other.

Next, the operating method of the disaster prevention lid according to the present invention will be explained. During normal use, the trough 1 is sealed without the cover plate 3 of the disaster prevention lid A being opened, but the power cable 1
When the pressure inside the trough 1 suddenly increases during a ground fault at 0, the free end sides of both sides of the cover plate 3 will move around the girder member 4 located approximately in the center as a fulcrum, as shown by the dotted lines in FIGS. 3 and 4. Pushed outward by internal pressure (above the drawing)
The trough 1 is curved into a substantially V-shape, the window hole 2 quickly opens, and the expanded air in the trough 1 is released to the outside. After the pressure is released, the cover plate 3 quickly restores itself due to its elastic action and the trough is sealed.

Furthermore, since the girder member is also made of an elastic material, even if the internal pressure rises rapidly in the event of a ground fault, in addition to the opening caused by the bending of the cover plate 3,
As shown in FIG. 5, the girder member 4 itself is also deformed in its longitudinal direction, that is, in an arcuate manner outward along the V-shaped trough of the cover plate 3, which has been deformed into a substantially V-shape. Therefore, it quickly absorbs the sudden pressure rise,
In addition, the elastic force of the girder member 4 promotes the elastic self-restoring action of the cover plate 3, and the cover plate 3 closes the window hole 2 of the trough more quickly after the gas pressure is released, thereby preventing air (oxygen) from entering the trough. ) can be blocked, thereby more reliably preventing damage to the trough.

As described above, the present invention covers a window hole formed in a power cable trough with a cover plate made of an elastic material and having an area larger than the opening area of the window hole so as to cover the window hole. A girder member made of an elastic material is stretched across the middle part of the cover plate and deforms the cover plate into a substantially V-shape in the event of a cable ground fault and curves outward in an arc along the troughs of the V-shape. , since this girder member is fixed to the trough and the cover plate is attached to the trough, the cover plate will close to approximately V when a cable ground fault occurs.
The lid plate not only deforms in a curved shape, but also curves outward in an arc along the V-shaped trough, opening the lid plate quickly, and the elastic force of the girder member causes the lid plate to open. Promoting its own elastic self-restoring action, the lid plate closes quickly. Therefore, the pressure relief effect is improved, and an abnormal pressure increase in the trough can be rapidly absorbed, and trough destruction and cable fire spread can be reliably prevented. Moreover, the structure of the disaster prevention lid according to the present invention is simple and can be easily installed at a site where it can be obtained at low cost.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional trough, Fig. 2 is a plan view showing an embodiment of the present invention, and Fig. 3 is a -
4 is a side view showing another embodiment of the present invention, and FIG. 5 is an explanatory view showing an example of the operating state of the present invention. A... Disaster prevention cover for power cable trough, 1...
Power cable trough, 2...window hole, 3...cover plate, 4...girder member.

Claims (1)

[Scope of utility model registration request] A cover plate made of an elastic material and having an area larger than the opening area of the window hole is placed over the window hole formed in the power cable trough so as to cover the window hole, and a cover plate is placed across the middle part of the cover plate to cover the window hole. , a girder member made of an elastic material that deforms the cover plate into a substantially V-shape and arcuately outward along the valley of the V-shape in the event of a cable ground fault is stretched, and this girder member is attached to the trough. A disaster prevention cover for a power cable trough, characterized in that a cover plate is fixedly attached to the trough.