JPS6217446B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for laying directly cooled power cables.

Generally, it is widely known that in order to increase the power transmission capacity of a power cable, it is necessary to cool the cable. Conventionally, in order to cool power cables, a so-called indirect cooling method was used, in which a small-diameter pipe was installed around the cable, and water was passed through the pipe to cool the cable. However, as cable insulation technology has improved in recent years, a direct cooling method has been proposed in which the cable is inserted into a watertight tube and the water pumped into the tube cools the cable directly. It's getting old.

By the way, the tunnel in which the cable is laid is constructed underground, and there are only manholes opened every few hundred meters between it and the ground. It is impossible to insert a long rigid pipe into this tunnel from a manhole, and it is necessary to insert a short pipe of several meters through the manhole and connect it within the tunnel, which requires a lot of effort. It required a lot of effort. Moreover, the cable must be inserted into the long tube constructed in this way. Conventionally, the method used was to forcibly pull the cable into the pipe using wires, etc., but this required a large amount of force and could damage the pipe or cable.
This was causing electrical and water leaks.

The present invention has been developed in view of the above circumstances, and is a method that allows a long pipe to be laid in a tunnel in one step, and at the same time, a cable is drawn into the pipe, thereby making it possible to very easily lay a direct cooling type cable. The purpose is to provide the following.

The present invention will be explained below based on the drawings. FIG. 1 is a cross-sectional view of a tunnel in which a directly cooled cable was installed using the method of the present invention. There are many shelves 2 in the cave 1.
are provided, and a direct cooling type cable 3 is placed on each of the receiving shelves 2. In the direct cooling type cable 3, a cable 5 having a diameter sufficiently smaller than that of the tube 4 is inserted into a tube 4, and cooling water 6 flows through the gap between the tube 4 and the cable 5, cooling the cable 5 directly from the outside. I'm starting to do that. A return pipe 7 is provided at the bottom of the tunnel 1 to allow water that has cooled the cable 5 to return for reuse. FIG. 2 is an enlarged cross-sectional view showing an example of the tube 4, in which a watertight tube 8' is attached to the inner surface of a cylindrical woven fabric 8.

FIG. 3 shows the implementation of the method of the invention. 9 is a manhole that leads to tunnel 1. 10 is a pressure vessel installed in the manhole 9, and a discharge port 11 is opened in the side wall of the pressure vessel. A compressed air pressure inlet 1 is provided at the top of the pressure vessel 10.
2 and a water inlet 13 are provided, and a compressed air pressure inlet 1
2 is connected to a compressor 14, and the water inlet 13 is connected to a water storage tank 16 via a pump 15. Further, a flexible cylindrical body inlet 17 is formed in the upper part of the pressure vessel 10.

18 is a flexible cylindrical body, and a watertight rubber or synthetic resin tube 8' is stuck to the outer surface of the cylindrical woven fabric 8. A string-like elongated object 19 is inserted over the entire length. The flexible cylindrical body 18 is wound around a reel 20 and placed outside the manhole 9. The flexible cylindrical body 18 is then reeled out from the reel 20.
enters the pressure vessel 10 from the flexible cylindrical body introduction port 17, and its tip is fixed to the discharge port 11 in an annular shape. Further, the string-like elongated object 19 protruding from the annular fixed portion passes over the receiving shelf 2 along the route on which the direct cooling cable 3 is to be laid, and passes through the next manhole 9.
At this point, it comes out of the manhole 9 and is connected to the take-up device 21.

In this state, a liquid such as water 22 is injected into the pressure vessel 10 from the water storage tank 16 by the pump 15,
Compressed air is supplied to the pressure vessel 1 by the compressor 14.
Press fit into 0. As a result, the water in the pressure vessel 10 is pressurized, and the water pressure causes the flexible cylindrical body 18 to
The annular fixed portion is pushed forward to form a folded portion 18a as shown in FIG. 4a.

In this state, when the string-like elongated object 19 is pulled by the pulling device 21, the flexible cylindrical body 18 is pulled forward and turned over at the folded portion 18a so that the inside becomes the outside. The flexible cylindrical body portion 18b is expanded into a circular cross section by water pressure.
Then, the flexible cylindrical body portion 18c which has not yet been turned over advances inside the turned flexible cylindrical body portion 18b, and is successively turned over at the folded portion 18a, and the folded portion 18a moves over the receiving shelf 2. Advance.
At this time, the amount of water that fills the interior of the inverted flexible cylindrical body portion 18b is supplied from the water storage tank 16 to the pressure vessel 10.

Next, the flexible cylindrical body 18 wound around the reel 20
Once all of the flexible cylindrical body 18 is pulled out from the reel 20, the take-up device 21 is stopped and the flexible cylindrical body 18
Connect one end of cable 5 to the free end of. This situation is shown in Figure 4b. In addition, cable 5
may be connected to the flexible cylindrical body 18 from the beginning. Then, when the pulling device 21 is further driven to continue turning over the flexible cylindrical body 18, the cable 5 passes through the inside of the pressure vessel 10 and is drawn into the turned over flexible cylindrical body portion 18b. Then, when the flexible cylindrical body 18 is turned over over its entire length, the turned over flexible cylindrical body portion 18b is placed on the receiving shelf 2, as shown in FIG. The cable 5 is now inserted inside.

Next, as shown in FIG. 4d, both ends of the flexible cylindrical body 18 are closed with lids 23 and 24, and one lid is provided with a water supply port 25 and the other is provided with a drain port 26. , 24, both ends of the cable 5 are connected to cables in adjacent tunnels,
Thus, a direct cooling type cable 3 is formed.

By the way, in this method, since the turned-over flexible cylindrical portion 18b is used as the pipe 4 of the laid direct cooling cable 3, the cylindrical cloth 8 is used as shown in FIG. It has a structure in which a watertight tube 8' made of rubber or synthetic resin is adhered to the inner surface, and is flexible. Therefore, if cooling water is passed between the pipe 4 and the cable 5, the pressure will cause the pipe 4 to swell into a circular cross-section, but if the pressure decreases or the water flow is temporarily stopped, the pipe 4 will maintain its circular cross-section. Unable to do so, it becomes flattened. Furthermore, the diameter and length tend to fluctuate due to fluctuations in the pressure of the cooling water, making them susceptible to damage by external forces.

In the present invention, the following method can be used to make the tube 4 rigid. That is, a reaction-curing synthetic resin liquid is applied to the inner surface of the flexible cylindrical body 18 in advance. Examples of the reaction-curing synthetic resin liquid include synthetic resins such as epoxy, unsaturated polyester, and acrylic resins. However, you can select an appropriate one among these. Then, this flexible cylindrical body 18 is turned over using the method described above, and the cable 5 is inserted into the turned-over flexible cylindrical body 18b. At this time, the reaction-curing synthetic resin liquid applied to the inner surface of the flexible cylindrical body 18 is removed by turning the flexible cylindrical body 18 over.
will adhere to the surface of the

Thereafter, the inverted flexible cylindrical body 18b is inflated to have a circular cross section, and the reaction-curing synthetic resin liquid is reacted and cured. In order to cure the reaction-curable synthetic resin liquid, it may be cured at room temperature over a long period of time, but the reaction-curing method can be achieved by passing hot water between the turned-over flexible cylindrical body 18b and the cable 5. Curing can be accelerated by heating the mold synthetic resin liquid.

According to this method, the tube 4 is given rigidity by the hardened synthetic resin, and will not be flattened or have its diameter or length changed. Further, when the flexible cylindrical body 18 is made of a cylindrical cloth and a tube as described above, the synthetic resin 27 hardens while permeating into the cylindrical cloth 8, as shown in FIG. This structure results in an extremely strong tube that is not easily damaged.

FIG. 7 shows a further improved method of this method. In the method shown in FIG. 7, a flexible tube 28 is laid in advance on the receiving shelf 2 in the tunnel 1 along the route where the direct cooling cable is to be laid.
Then, the tip of the flexible cylindrical body 18 whose inner surface is coated with a reaction-curing synthetic resin liquid and one end of the tube 28 are fixed to the discharge port 11 of the pressure vessel 10 in an annular manner, and are inserted into the flexible cylindrical body 18. The string-like elongated object 19 is inserted into the tube 28. When the flexible cylindrical body 18 is turned over by pulling the string-like elongated object 19 in this state, the folded part 18a moves forward within the tube 28, and the turned-over flexible cylindrical body part 18b reacts with the reaction. It is brought into pressure contact with the inner surface of the tube 28 via a curable synthetic resin liquid. When the flexible cylindrical body 18 is turned over over its entire length, the reaction-curing synthetic resin liquid is caused to react and harden.

In the method described above, since the reaction-curing synthetic resin liquid is exposed and adhered to the surface of the turned-over flexible cylindrical body 18b, the reaction-curing synthetic resin liquid flows down and prevents thickness unevenness. The pipes 4 that have formed or formed are adhered to the receiving shelf 2 by the reaction-curing synthetic resin, and cannot be replaced even if the pipes become obsolete.However, according to this improved method, as shown in Figure 6. As shown in the figure, since the tube 28 is located on the outermost surface of the tube 4, the reaction-curing synthetic resin liquid does not flow down or the tube and the shelf adhere to each other. If there is any local unevenness, the inverted flexible cylindrical body 18b presses against the tube 28 to even out the unevenness.
The thickness becomes uniform.

In the present invention, the flexible cylindrical body 18 is turned over and the sinus 1 is
Since the cable 5 is laid inside the tube 4 and the cable 5 is drawn into the tube 4 at the same time, a long direct cooling type cable 3 can be laid in one step. Therefore, the construction work can be completed in a short period of time, and is inexpensive and labor-saving. Furthermore, in the inventions set forth in claims 2 and 3, since the inverted flexible cylindrical body 18b is given rigidity using a reaction-curing synthetic resin, the pressure of the cooling water is reduced. It will not be deformed by fluctuations and will not be damaged by external forces. Furthermore, in the present invention, since a liquid is used as the pressure fluid when turning the flexible cylindrical body 18 over, the frictional resistance when the cable 5 moves inside the turned over flexible cylindrical body 18b is reduced. is small, and the buoyant force of the liquid acts on the cable 5, and the cable 5 moves in the direction of the liquid flow, so a large force is not required to pull the cable 5, and the cable 5 and its flexible There is no damage to the cylindrical body 18. In the present invention, the liquid is not limited to water, and other liquids may be used. In particular, in order to increase the liquid force acting on the cable 5, it is preferable to use a liquid with a higher specific gravity, such as salt water. .

Furthermore, the method of the present invention can be applied not only to the case where the cooling type cable 3 is laid directly on the receiving shelf 2 in the tunnel 1, but also to the case where the cable is laid inside an existing pipe such as an asbestos pipe.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a tunnel in which a direct cooling cable is installed. FIG. 2 is a partially enlarged cross-sectional view showing an example of a tube in a direct cooling cable laid by the method of the present invention. FIG. 3 is a longitudinal cross-sectional view showing the construction state of one method of the present invention;
The figure is a schematic diagram showing the construction process. 5 and 6 are partially enlarged cross-sectional views showing other examples of tubes in a direct cooling cable laid by the method of the present invention, respectively. FIG. 7 is a longitudinal sectional view showing the construction state of another method of the present invention. 3... Direct cooling type cable, 4... Tube, 5...
Cable, 18... Flexible cylindrical body, 19... String-like long object, 28... Tube.

Claims (1)

[Claims] 1. A string-like elongated object is inserted into a flexible cylindrical body over its entire length, one end of the flexible cylindrical body is fixed in an annular shape, and the end of the flexible cylindrical body is fixed to the rear part of the annular fixed part. While applying hydraulic pressure, the string-like elongated object protruding from the annular fixed part is pulled forward, and at the folded part formed in the annular fixed part, the flexible cylindrical body is turned over so that the inside becomes the outside. The folded portion is advanced forward, one end of the cable is coupled to the other end of the flexible cylindrical body, and the flexible cylindrical body is turned over over its entire length, thereby turning the cable into an inverted flexible structure. A method of laying a direct cooling type cable, which is characterized by being inserted into a cylindrical body. 2 Apply a reaction-curing synthetic resin liquid to the inner surface of the flexible cylindrical body, and insert a string-like elongated object into the flexible cylindrical body over its entire length. One end is fixed in an annular shape, and while applying hydraulic pressure to the rear part of the annular fixed part, the string-like elongated object protruding from the annular fixed part is pulled forward, and the folded part formed on the annular fixed part is Flip the flexible cylindrical body over so that the inside is facing outward, advance the folded part forward, connect one end of the cable to the other end of the flexible cylindrical body, and then turn the flexible cylindrical body over. By turning over the entire length, the cable is inserted into the turned-over flexible cylindrical body, and while the flexible cylindrical body is inflated to a substantially circular cross section, the reaction curing synthetic resin liquid is cured. A method for laying a direct cooling cable, characterized by imparting rigidity to a flexible cylindrical body. 3. A flexible tube is laid along the route where the direct cooling type cable is to be laid, and at the same time, a reaction-curing synthetic resin liquid is applied to the inner surface of the flexible cylindrical body. A string-like elongated object is inserted over the entire length, one end of the flexible cylindrical body and one end of the tube are fixedly supported in an annular shape, and hydraulic pressure is applied to the rear part of the annular fixed part. The string-like elongated object protruding from the annular fixed part is pulled forward through the tube, and at the folded part formed in the annular fixed part, the flexible body is turned over so that the inside becomes the outside, and the folded part is turned over. The flexible cylindrical body is moved forward inside the tube and pressed against the tube, one end of the cable is connected to the other end of the flexible cylindrical body, and the flexible cylindrical body is moved along its entire length. By turning the flexible cylindrical body over, the flexible cylindrical body is inserted into the tube and brought into pressure contact with the inner surface of the tube. A direct cooling type cable, characterized in that the flexible cylindrical body and the tube are made into a pipe having integral rigidity by curing the reaction-curing synthetic resin liquid in a state in which the tube is inflated to a substantially circular cross section. Laying method.