JPS5820209B2 - 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 plastics containing flame-retardant additives such as aluminum hydroxide or concrete IJ-containers have been widely adopted. Its heat resistance and suffocating fire extinguishing effect due to its airtight sealing structure prevented the spread of fire in the cable due to the arc that would occur in the event of a cable ground fault.

However, with the recent appearance of 500 KV class ultra-high voltage, large capacity OF cables, the power transmission capacity of lines has increased, and the arc energy at the ground fault point of the installed cable tends to become significantly more intense, increasing the risk of ground fault accidents on cable lines. When a ground fault occurs, most of the cable's constituent materials, including the insulating oil inside the cable near the ground fault point, instantly explode into gas due to this arc energy, and the pressure inside the trough increases significantly, so conventional closed-type troughs are unable to withstand the internal pressure. There is a risk that the cables in the trough may fail and the cables inside the trough may spread, causing widespread damage.

In addition, pressure relief valves are installed in airtight troughs that house cables, but cable ground faults occur with a certain probability at any point along the line, and internal pressure increases due to ground faults are Since the attenuation is most noticeable and rapid in the line extension direction within 1 m of the ground fault point, pressure relief valves must be installed at small intervals in the longitudinal direction, and ground fault accidents can occur even with 275KV class cables. and the gas pressure in the trough is 10k
Since the pressure rises above g/CTL, there is a risk that the pressure relief valve near the ground fault will be destroyed and outside air will enter the trough.

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 from the notch, and prevents destruction of the trough due to abnormal gas pressure.
We would like to provide a disaster prevention trough that has the function of immediately restoring itself to an almost original sealed state after pressure is released, and preventing the spread of fire to laid cables due to outside air intrusion beyond the extremely slight air circulation in the notch. That is.

An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a trough body, and 2 a lid body airtightly attached to the trough body 1. The lid body 2 is made of highly elastic flame-retardant reinforced plastic. As shown in Figures 2 and 3, on both sides of the inner surface, there are radial notches in the shape of * or a cross, with a depth of at least 90 times the thickness of the lid and a width approximately equal to the thickness of the lid. Pressure release parts 3 are provided at predetermined intervals over the entire length.

Note that this cut pressure release part 3 may be provided with a cut that penetrates the surface of the lid body 2, if necessary, and a thin glass fiber mat of about 0.5 to 1.0 mm may be pasted from the trough surface for sealing.

The present invention is as described above, and the abnormal gas pressure in the trough that occurs when a cable ground fault occurs is quickly absorbed and released by the plurality of notched pressure relief sections 3 located at the occurrence point expanding outward greatly instantaneously. After the pressure is released, the trough shape is immediately restored to its original shape due to the elasticity of the lid itself. Due to the elasticity of the pressure release part 3, it immediately returns to the sealed state, and the intrusion of outside air is blocked by leaving only a thin fracture line on the surface of the pressure release part.

Therefore, even if a fire breaks out in the cable break hole in the trough, if the oxygen concentration reaches 15% or less, the fire will be extinguished by suffocation due to lack of oxygen, even if a small amount of outside air may enter through the cut break line. The fire self-extinguishes because the oxygen consumption rate in the fracture hole is faster.

According to the present invention, as described above, the radial cut pressure relief part 3 having a depth of 90 times or more of the thickness of the lid is formed on the inner surface of the trough lid 2 made of highly elastic flame-retardant reinforced plastic. Since they are arranged in parallel, the pressure relief part 3 can instantly bulge outward due to the gas pressure generated within the trough, and can quickly absorb abnormal gas pressure to prevent damage to the trough. Since it immediately returns to its original state after compression, it has an excellent effect of reliably preventing the spread of fire to the cable due to large amounts of outside air entering.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the trough of the present invention, FIG. 2 is a plan view, and FIG. 3 is an enlarged sectional view showing the main parts. 1: Nidraf main body, 2: lid body, 3: pressure release part.

Claims (1)

[Claims] 1. On the inner surface of the lid made of highly elastic flame-retardant reinforced plastic that is airtightly attached to the trough body,
A disaster prevention trough having a depth of 0% or more and having radial cut pressure relief parts arranged at predetermined intervals that self-restore after instantaneously expanding due to abnormal gas pressure generated within the trough. .