JPS58218814A - Method of cooling offset power cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cooling an offset portion in a manhole of an electric power cable installed in an underground conduit or tunnel and directly cooled by cooling water.

It is known that forced cooling is conventionally applied to high-voltage, ultra-high-voltage cables and cable cables installed underground in cities in order to increase the power transmission capacity per line. Types of forced cooling include the direct pipe water cooling method, in which cooling water is passed through the gap between the cable and the conduit in the power cable installed in the conduit, and the direct water cooling method in which cooling water is passed into the gap between the cable and the conduit in which the cable is housed. A pipe indirect water cooling system in which water is passed through is known. Recently, it has become difficult to construct conduits for laying underground cables close to the ground surface due to the congestion of buried objects. This method of laying cables has come to be adopted.

Such cables inside the tunnel are also cooled in the same way as described above.

If necessary, a direct water cooling system for the pipe in the tunnel has been experimentally attempted, in which a pipe is further installed in the tunnel, a cable is passed through the pipe, and then the cable is directly cooled with water.

The power transmission capacity of a power cable subjected to such forced cooling can be increased by about 30 to 50% with indirect cooling, and by about 100% with direct water cooling, compared to the case without cooling.

In order to secure space during connection work in the manhole where all the cables are connected, as shown in the conventional example shown in Figure 1, the cables Ki It is necessary to take a distance (this is called an offset), so the length of the offset part 2 is approximately 511 mm.
2 is very difficult to cover with a cooling pipe like the pipe section 23, and normally the cooling water is connected to the water stop device 24 at the pipe port 20.
The water is stopped and bypassed by the bypass pipe 25. 26 is the city, the joint of Kacaple 1.

Therefore, there is no cooling water on the surface of the hollow cable 21 of the offset section 22, and a problem arises in that the power transmission and capacity of the offset section 22 is smaller than that of the conduit section.

If the transmission voltage is up to Sunagawa 54 KV class #, the electrical insulation layer of the cable is relatively thin, so heat dissipation is good, and the dielectric loss that occurs in the insulation layer is small, so one offset section can be left uncooled. Even if left at 1, the offset section will not reduce the power transmission capacity of the cable system.

However, even if it is +54 KV class, there are cases where even larger power transmission capacity is required, or when the power transmission voltage is 275 to 500 KV.
As the voltage increases, the insulation layer becomes thicker and the dielectric loss also increases in proportion to the square of the voltage.If the offset section is left uncooled, the offset section becomes a bottleneck in power transmission and capacity. becomes. Therefore, cooling to the same extent as the pipe section is required.

The present invention aims to provide a method for cooling the power cables in the offset part in the above-mentioned case by making it possible to water-cool the power cables in the offset part and increasing the power transmission capacity of that part to the same extent as in the conduit part. be.

Performance requirements for a device that wraps the surface of the offset portion of a power cable in cooling water and cools it include the following.

■ It should adhere well to the cable surface.

If an air layer remains between the off-cent cable and the cooling device, heat transfer will deteriorate, so make sure they are in good contact.

(V. Must be Fungi/Puru.

Since the shape of offset slack is often not uniform and three-dimensional, it is difficult to process it in advance to match the shape of the cable at the factory, so it is possible to order it on-site to match the shape of the cable. something is needed.

In addition, since the slack shape of the cable in the offset section changes due to daily and annual temperature changes, it is necessary to follow this deformation.

(■ Pressure loss due to water flow is small.

In the pipe section, cooling water flows through the gap between the cable and the pipe, but if the pressure loss is too large compared to the pressure loss in this part, the discharge pressure of the water pump becomes a sieve, and the cooling water circulation is interrupted. The pressure in the system is increasing and things are not looking good.

■ Must be removable.

The offset section is frequently visited by workers, and there is a possibility of injury. In addition, as the cable changes by M degree, the shape of the cable sag repeatedly changes, and this causes a fatigue cracking noise in the metal base of the cable, and there is a high risk of oil leakage. In such cases, the cooling system must be removable and repairable.

■ The middle of the offset part can be fixed with a cleat.

In order to reduce the number of manholes, it is often necessary to reduce the length and width of the offset by suppressing the expansion and contraction of the cables in the conduit due to temperature changes. In such a case, it is necessary to fix the offset portion of the cable to the floor or wall at several points along the way with cleats.

The present inventor has studied various methods for cooling the offset portion that meet the above-mentioned requirements, and has come up with the present invention that satisfies all of them.

That is, the present invention provides a pair of half-shaped cooling devices in which a plurality of hoses are arranged in a semicircular shape and connected to the outer periphery of the power cable in the offset section, between the henders having a semicircular fan-shaped cross section at both ends. This is a method for cooling an offset metropolitan electric cable cable, which is characterized in that after the device is heated, the outer periphery of the hose 11f is bound at one or more locations, and all cooling water connecting pipes are connected to the hoses at both ends.

υ Below, the present invention will be explained by examples using the drawings.

FIG. 2 is a side view showing an example of an off-center portion of a power cable installed according to an embodiment of the present invention.

In the figure, the power cable 1 that has exited the conduit port 20 has a cooling pipe 2 on the outside, through which cooling water 11 is passed.

The cooling pipe 2 is cut before the offset portion 22, and water is cut off by a water cutoff device 3.

FIG. 3 is a diagram showing each part of FIG. 2, and FIG. 3A and FIG. Figure 2) shows the front and side views of the connection between the header and the hose group, and figure 5) shows the spacer shown in figure 3.

FIG. 4 is a perspective view showing the state before the electric cable is attached to the half-split type cooling device of the offset section in the embodiment of the method of the present invention.

A pair of half-split cooling devices (Oa, Job (not shown) shown in FIG. 4) are covered on both sides of the outer periphery of the power cable 1 in the nocent portion. Half-split type cooling device 10
a (or 10b, the same hereinafter) has a cooling water header 6a (6b) with a semicircular fan-shaped cross section at both ends, I6a (
16b), each having a connector 7.
A plurality of hoses 5 are arranged in a semicircular manner via 17; (
Fig. 3 c), they are connected. (16b is not shown.) The headers 6a, 6b, 16a, +6b are
The inside has a semicircular surface that fits the outer circumference of the cable 1, closed on one side, and on the other side a connector 7.17 for distributing cooling water to each hose 5 is arranged.

The connections between the headers 6a, 6b, 16a, 16b and the port group 5 are as shown in FIG. 6a) are connected by a connector ('7). A gap is created between the hose group 5 and the surface of the power cable 1 as shown in the figure (c), and the thermal resistance when the heat of the cable 1 is transmitted to the cooling water in the hose 5 becomes large. In order to prevent this, a spacer 13 with a mountain-shaped cross section as shown in Figures 0-9 is inserted into the gap between the I and I.

Cooling water connecting pipes 4a, 4b are connected between the headers 6a, 6b and the 1-capule cooling pipe 2 of the pipe port 20, respectively.
headers 16a and 16b at the other end.
Similar headers (not shown) at the offset section on the other side of the joint 26 are connected by cooling water connecting pipes 9a and 9b (joint section bypass pipes), and these are all connected by half-way pipes. [Split type cooling device] Cooling water 11 is circulated within Oa and Job.

Cooling water connection pipes 4a, 4b, 9a, 9b, hose 5
For this purpose, flexible rubber or plastic hoses, metal bellows, etc. are used. 'Since the constant water pressure is about 5 KI'a in gauge pressure, if it is made of rubber or plastic, fibers may be woven into the intermediate layer to reinforce the internal pressure if necessary. Further, for metal bellows pipes, it is necessary to coat the surface with an anticorrosion layer such as a plastic layer for corrosion resistance.

Also header 6a, 61), I 6a, I 6b,
Connector 7. The 17° hose fitting 12 is made of a metal with excellent corrosion resistance, such as copper, copper alloy, stainless steel, etc., and the spacer 13 is made of a material that is flexible and has very low thermal resistance. For example, a polyethylene extrusion molded product is used.

Next, in order to install the offset section cooling device having such a structure by the method of the present invention, the headers 6a, 16a (or 6b, +6b) are installed in advance at the factory as shown in FIG.

The hose group 5 and connectors 7 and 17 are connected and assembled into a semicircle to create a pair of half-split cooling devices 10a and IOb. At the site, as shown in Figure 2, after covering the outer periphery of the electric cable ■ in the offset section from both sides,
The cooling devices 10a and 10b are fixed to the cable 1 by binding the outer periphery of the cooling device 10a and 10b with a band 8 or the like at one or more locations at intervals. This binding portion is used for fixing to the floor or wall with a cleat if necessary, and may be provided at one or more locations depending on the installation conditions.

As the band 8 or the like, a metal or plastic band, or a bind made by impregnating epoxy resin and glass tape, winding the band, and hardening the band is used.

Then header 6a, 61), 16a of circle I11,
16b, cooling water connection pipes 4a, 4b, 9a,
9b'ji7 is connected, and the cooling water 11 is sent to the cooling bag [10a,
Allow it to circulate in IOb.

If necessary, the band 8 and the like are fixed to the floor or wall with cleats to complete the installation work.

The cooling method of the present invention configured as described above has the following effects.

(b) As mentioned above, connect multiple hoses around the outer circumference of the offset part's capeple between the headers at both ends. M
I-ka. 8. Ya, care, after 6□.

Since the hose group is bound at one or more points on the outer periphery of the hose group and the cooling water connection pipes are connected to the headers at both ends, the hose group directly contacts the surface of the cable and is cooled by the cooling water. It will be possible to increase the power transmission capacity in the same way as the conduit section. Note that the surface of the cable
Since a spacer with a cross-section of a mountain cross can be inserted into the gap between the hose groups, there is no air layer, so heat transfer from the cable to the cooling water in the hose is good.

(b) The split type cooling device is assembled in advance at the factory and is simply placed on both sides of the capeple on site, so it is easy to attach and detach, and it can be freely adapted to any curved shape of the offset part. It is.

(c) Since the hose can be made of rubber, plastic, or metal bellows with an anti-corrosion layer, there is no fear of corrosion over many years.

) The cable can be gripped at any point from above the binding part or the hose, so for example, if you fix the cable to the ground at several points in the middle of an offset Toden cable, the cable in the conduit can be held at the offset part. It is possible to easily suppress all expansion due to thermal expansion, and as a result, offset dimensions (width, length) can be reduced.

It is easy to use a so-called non-set method.

(e) Since the cooling water is divided by multiple hoses, the drop in water pressure at the offset section is small.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an example of an offset portion (Pi) of a conventional convertible cable. FIG. 2 is a side view showing an example of an off-cent portion of a cable cable installed according to an embodiment of the method of the present invention. Figures 3 (a) to 0i are diagrams showing each part of Figure 2, and (a)
Figures and (b) are A-A' and B-B shown in Figure 2, respectively.
Figure 1 shows the cross section, (c) Figure 2, ←) shows the front and side views of the connection between the header and the hose group, and (e)
The figure shows the spacer shown in (c) figure. FIG. 4 is a perspective view showing the state of the front wheel to which the electric cable is attached in the half-split type cooling device of the offset section in the embodiment of the method of the present invention. - 1, 21... chemical cable, 2... cooling pipe, 3, 24...
Water stop device 1 piece, 4a, 4b, 9a, 9b-cooling water connection pipe, 5, hose, 6.16...header, 7,
17... Connector, 8 band, IOa, job.
...Half-split cooling device, 11..Cooling water, 12..Hose metal JL, 13..Spacer, 20..Pipe line 1.
J, 22・offset section, 23...pipe section, 25...
Bypass 'II, 26...Joint.

Claims (3)

[Claims] (1) The outer periphery of the power cable in the offset section is covered with a pair of half-split cooling devices in which multiple ports are arranged in a semicircular pattern and connected between headers with a semicircular fan-shaped cross section at both ends. After that, bind the outer periphery of the hose group at least ■ points,
1. A method for cooling a 1-capule offset metropolitan den, characterized in that cooling water connecting pipes are connected to the headers at both ends. (2) The off-cent Toden cable according to claim 1, wherein a spacer having a mountain-like cross section is inserted into the gap between the surface of the cable and the port group when the half-split cooling device is placed over the outer cylinder of the cable. - Method of cooling the pull. (3) The hose is rubber or plastic,
or a metal bellows with an anti-corrosion layer.
2. A method for cooling an offset metropolitan electric capeple according to paragraph 2 or paragraph 2.