JPS5924613B2 - disaster prevention trough - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a disaster prevention trough for accommodating and laying ultra-high voltage OF cables.

Conventionally, as a disaster prevention measure for ultra-high-voltage OF cables housed in troughs, closed disaster prevention troughs made of reinforced plastic containing flame-retardant additives such as aluminum hydroxide, or concrete, etc., have been widely adopted. Due to its heat resistance and suffocation extinguishing effect due to its airtight sealing structure,
This prevents the spread of cable fires that occur during cable ground fault accidents.

However, with the recent appearance of 500KV class ultra-high voltage and large capacity OF cables, the power transmission capacity of the line has increased, and the arc energy at the ground fault point of the installed cable has become significantly more intense.
When a ground fault occurs on a cable line, most of the cable's constituent materials, including the insulating oil inside the cable near the ground fault point, instantly explode and turn into gas due to the arc energy, and the pressure inside the sealed trough increases significantly. There is a risk that a closed trough may not be able to withstand the internal pressure and break, causing damage to the cable and the spread of fire over a wider area.

In order to prevent potential accidents, attempts have been made to install pressure relief valves in airtight troughs that house cables, but cable ground faults can occur not only at a fixed point but at any point.
Because the increase in internal pressure due to a ground fault is most noticeable in the 1 m area near the ground fault point and is rapidly attenuated in the line extension direction, pressure relief valves must be installed at small intervals in the longitudinal direction, and at 27SKV
If a ground fault occurs even in a cable with a high-grade cable, the gas pressure in the trough will rise to more than 10 νd, and the pressure relief valve near the ground fault will be completely destroyed, causing a large amount of outside air to enter the trough and causing damage to the fire. is likely to expand.

In view of the above points, the present invention promptly releases abnormal gas pressure in the trough that occurs when a ground fault occurs in a laid cable to the outside,
An object of the present invention is to provide a disaster prevention trough having a function of preventing the trough from being destroyed due to abnormal gas pressure, and self-returning to the original sealed state immediately after pressure is released, thereby preventing the spread of fire in the laid gouple due to outside air intrusion into the trough. It is.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings, in which 1 is a U-shaped trough body configured so that the terminal portion can be fitted and connected;
Reference numeral 2 denotes a U-shaped differential member whose side plate ends are airtightly fitted into fitting grooves 3 formed at the upper ends of both side plates of the trough body 1, and the lid body 2 is made of highly elastic flame-retardant reinforced plastic. As shown in FIGS. 1 and 3, this lid body 2 has two slits 4 parallel to each other along the axis from the end at one end thereof, and a small circle at the end of the slit 4. A hole 5 is drilled,
A fitting stepped portion 6 is formed at the other end of the lid body 2.

Thus, two parallel slits 4 formed in the lid body 2,
4, based on the results of the ground fault experiment, the width of the slits 4, 4 is optimally 5 degrees or less, and the length of the slit is 550 mm or more, and by specifying this, the movable piece 4a between the two parallel slits 4, 4 The trough is rapidly pushed outward by the gas pressure generated at the time of a ground fault, and after releasing the gas, it immediately returns to its own position on the fitting part of the adjacent lid, blocking outside air from entering the trough.

Reference numeral 7 denotes a stainless steel band having a tensile strength of about 800 kg, which binds and fixes the trough body 1 to which the lid 2 is airtightly attached and the lid 2 at intervals of 600 to 800 strokes.

Next, to explain a specific example of the present invention, as shown in FIG.
A lid body 2 with a width W, in which two parallel slits 4, 4 of 0 to 650 mm are provided at one end, is airtightly mounted on the trough body 1 housing the cable at a line voltage of 500 KV.
The results of a ground fault experiment conducted under the conditions of a ground fault current of 50 KA are shown in the following table.

According to the present invention, as is clear from the above experimental results, the ratio W of the slit interval W' to the width W of the trough lid body
If '/W is 0.5 or more, the strength of the lid body may decrease and it may be damaged. If the slit length is less than 550 mm, sufficient pressure relief effect cannot be obtained, and the end portion of the lid body 2 may be damaged. The ratio of the mutual distance W' of the slits 4 to the width W of the lid body 2 is 0.4.
~0.5, the length l of slit 4 is 550mm ~650
The trough lid body 2 is made of highly elastic flame-retardant reinforced plastic, and has two parallel slits 4 of the required length extending from the end along the axis line. 4 is provided, and by opening and closing the movable piece 4a between the slits 4 and 4, the abnormal gas pressure generated in the event of a cable ground fault in the trough is immediately released to the outside to prevent the trough from being destroyed. Since the movable piece 4a immediately returns to its original sealed state by self-returning, it has an excellent effect of reliably preventing the spread of fire to the cable due to the intrusion of a large amount of outside air.Moreover, the shape and processing of the slit provided in the lid body is easy. It has the advantage of being suitable for mass production and being available at low cost.

It should be noted that the present invention is not limited to the embodiments described above, and it goes without saying that materials, shapes, configurations, etc. can be changed as appropriate within the scope of the present invention.

[Brief explanation of drawings]

The figures show one embodiment of the present invention, and FIG. 1 is a plan view;
Fig. 2 is a sectional view taken along the line X-X of Fig. 1, Fig. 3 is an explanatory view of the lid, Fig. 4 is an explanatory view showing the pressure relief operating state, and Fig. 5 is an explanatory view showing a specific example of the present invention. It is. 1 Nidrough body, 2: Lid body, 3: Fitting groove, 4 Nislit, 5: Small hole, 6: Fitting step, 7: Stainless steel band.

Claims (1)

[Claims] 1 Two parallel slits with a mutual spacing of 1/2 or less of the width of the lid and a length of 550 mm or more are placed at one end of the lid made of highly elastic flame-retardant reinforced plastic along the axis from the end. 1. A disaster prevention trough, characterized in that the end portion of the lid body is sequentially wrapped over the end of an adjacent lid body and is airtightly fitted and fixed onto the main body of the laying trough.