JP3418282B2 - Direct cooling power cable - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct cooling power cable for directly cooling the cable in order to increase the power transmission capacity of the power cable.

[0002]

2. Description of the Related Art Conventional methods for cooling a cable are roughly classified into a direct cooling type in which a cable and a cooling medium are brought into direct contact with each other for cooling, and an underground tunnel (cave) in which a cable is laid. There is an indirect cooling type in which a cooling pipe is provided and cooling is performed via ambient air.

Among them, the direct cooling type has an advantage that it can be cooled efficiently. As one method of the direct cooling type, there is one in which a cable is drawn inside a cooling pipe through which a coolant such as water passes. However, in that system, the cooling pipe and the cable are not integrated, so that there are various inconveniences. For example, when winding a manufactured long cable on a drum, it is necessary to wind the drum while pulling the internal cable, but it cannot be grasped because the cable is inside the cooling pipe, and the Due to expansion
The cable behaves differently from the cooling pipe, and excessive mechanical force or deformation occurs between the two, which is not preferable. Therefore,
In order to avoid such a problem, a large number of small-diameter cooling pipes are spirally wound around the outer circumference of the cable to integrally form the cable and the cooling pipe (for example, an actual product has been developed. (See Japanese Laid-Open Patent Publication No. 56-101825).

FIG. 6 is a view showing a conventional direct cooling power cable formed by spirally winding a large number of cooling pipes around the outer circumference of the cable. In FIG. 6, 1 is a conductor, 2 is an inner conductive layer, 3 is a plastic insulator, 4 is an outer conductive layer, 1
Reference numeral 0 is a shielding layer, 11 is a metal tube, and 12 is an anticorrosion layer. A large number of metal pipes 11 having a small diameter are spirally wound at an appropriate pitch on the outer circumference of a cable core composed of the conductor 1, the plastic insulator 3, the shielding layer 10 and the like, and the anticorrosion layer 12 is formed thereon.
Then, cooling water is caused to flow inside each metal tube 11 to cool the cable main body.

[0005]

However, the above-mentioned conventional technique has a problem that the bending rigidity of the metal tube 11 is large and the bending diameter of the cable is limited. Further, since the contact area between the metal tube 11 and the cable body is small, there is a problem that the cooling effect is small.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide a direct cooling power cable having a small limitation on the bending diameter of the cable and a large cooling effect.

[0007]

In order to solve the above-mentioned problems, in the direct-cooling power cable of the present invention, a water-impervious sheath is formed on the outer periphery of the cable core, and the pipe wall is water-permeable on the outside thereof.
A flexible metal pipe through which a cooling medium flows is provided inside, and the outside is covered with an external watertight pipe. Further, as the flexible metal pipe, a metal tape having a substantially S-shaped cross section,
It was decided to use an interlock tube that was formed in a spiral shape so that both edges were intermeshed with each other. As the flexible metal tube, a spiral tube formed by spirally forming metal tapes having a substantially C-shaped cross section, which are opposed to each other in upper and lower two layers, and whose both end edges are intermeshed with each other, is used. The flexible metal tube has a rectangular cross section.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention. Reference numerals 1 to 4 correspond to those in FIG. 6, 5 is a water shield sheath, 6 is an anticorrosion layer, 7 is a flexible metal tube,
Reference numeral 8 is a space portion, and 9 is an external watertight pipe.

On the outer periphery of the conductor 1, the inner conductive layer 2, the plastic insulator 3 and the outer conductive layer 4, a water shield sheath 5 made of a metal such as aluminum, stainless steel or lead is formed, and polyethylene, polyvinyl chloride or the like is formed thereon. It is covered with an anticorrosion layer 6 made of plastic. A plurality of flexible metal pipes 7 having a small bending rigidity and a water-permeable pipe wall are wound around the outer periphery of the anticorrosion layer 6 in a spiral shape. An outer watertight pipe 9 is covered therewith to form a sealed space 8 between the anticorrosion layer 6 and the outer watertight pipe 9.

When a cooling medium such as water flows through the flexible metal pipe 7, the cooling medium flows out into the space 8 because the wall of the flexible metal pipe 7 has water permeability. It flows in it. In this way, the cooling medium spreads inside and outside the flexible metal tube 7 and cools the entire outer circumference of the cable body, so that a large cooling effect is obtained. Further, since the flexible metal tube 7 has small bending rigidity and flexibility, the bending diameter of the cable is not so limited.

Next, the flexible metal tube 7 will be described.
FIG. 2 shows an interlock type flexible metal tube. In this way, the interlock-type flexible metal tube in which the metal tape having a substantially S-shaped cross section is formed into a spiral shape, and the both end edges are engaged with each other, the interlock portion can slide, and the cable body is Even when subjected to bending, bending strain can be sufficiently absorbed. Also, the interlock part
Since there is no water tightness, the cooling medium flows out from the inside of the pipe,
It can be sufficiently spread in the space 8 on the surface of the cable body.

Further, the flexible metal tube 7 may be a flexible metal tube 7 having a rectangular cross section as shown in FIG. As shown in FIG. 4, the rectangular cross-section flexible metal tube 7 has
A metal tape having a square S-shaped cross section is formed by winding it into a square spiral while engaging both end edges with each other. As described above, when the flexible metal pipe 7 has a rectangular cross section, the displacement of the flexible metal pipe 7 is less likely to occur when the direct-cooling power cable receives lateral pressure, and the unevenness of the surface is reduced. can do. Moreover, since the passage of the cooling medium can be made large, an even greater cooling effect can be obtained.

Further, as the flexible metal tube 7, as shown in FIG. 5, metal tapes having a substantially C-shaped cross section are made to face each other in upper and lower layers, and both end edges are meshed with each other to form a round or square spiral. It is also possible to use a product that is rolled into a shape. In addition, a flexible and water-permeable pipe wall structure, such as one in which a flat metal tape is simply wound, or one in which a large number of holes are formed in the wall of a corrugated metal pipe to ensure water permeability, Any of the above can be used.

The material of the flexible metal tube 7 is preferably one which is free from problems such as corrosion by a cooling medium and has good workability. For example, stainless steel, copper or copper alloy can be used.

Although the flexible metal tube 7 is spirally wound around the cable body in the above example, it may be simply attached vertically to the cable body.

[0016]

As described above, according to the direct cooling power cable of the present invention, the cooling pipe can be integrated with the cable body. As a result, the cooling pipe can be made to behave in the same manner as the thermal expansion of the cable main body due to heat generation when the cable is energized, and no excessive mechanical force or deformation is generated between the two. Further, since the bending rigidity of the flexible metal tube is small, there is less restriction on the bending diameter of the cable. Furthermore, since the cooling medium penetrates around the flexible metal tube,
A great cooling effect can be obtained.

Further, according to the direct-cooling power cable of the second and third aspects, it is possible to slide at the engaging portions of the both end edges of the metal tape, through which the cooling medium is well passed, and the cable body is bent. Then, the bending strain can be sufficiently absorbed.

Further, according to the direct cooling power cable of the present invention, since the flexible metal tube has a rectangular cross section, the position variation of the direct cooling power cable when the lateral pressure is applied is reduced, and Surface irregularities can be reduced. Moreover, since the passage of the cooling medium can be made large,
A greater cooling effect can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an interlock-type flexible metal tube.

FIG. 3 is a diagram showing a case where a flexible metal tube having a rectangular cross section is used.

FIG. 4 is a diagram showing an example of a rectangular cross-section flexible metal tube.

FIG. 5 is a diagram showing another example of a flexible metal tube.

FIG. 6 is a diagram showing a conventional direct cooling power cable.

[Explanation of symbols]

1 conductor 2 Internal conductive layer 3 plastic insulators 4 External conductor 5 Impermeable sheath 6 Anticorrosion layer 7 Flexible metal tube 8 space 9 External watertight pipe 10 metal tubes 11 Anticorrosion layer

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukishi Fuku 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (56) Reference JP-A-6-159561 (JP, A) JP-A 6-286014 (JP, A) JP-A-6-325625 (JP, A) JP-A-7-55071 (JP, A) Actually opened 56-101825 (JP, U) Actually opened 5-17849 (JP, A) U) Actual Kaihei 5-20210 (JP, U) Actual public Sho 38-23645 (JP, Y1) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01B 7/42 H01B 9/06 H01B 7 / 28

Claims (4)

(57) [Claims] 1. A water shield sheath (5) is formed on the outer periphery of a cable core, and a flexible metal pipe (7) having a water-permeable pipe wall and flowing a cooling medium therein is provided on the outer side thereof, and A direct cooling power cable whose outer side is covered with an external watertight pipe (9). 2. The flexible metal pipe (7) is an interlock pipe formed by spirally molding a metal tape having a substantially S-shaped cross section so that both end edges are engaged with each other. Item 3. A direct cooling power cable according to item 1. 3. The flexible metal pipe (7) is a spiral pipe formed by spirally forming metal tapes having a substantially C-shaped cross section, which are opposed to each other in upper and lower two layers, so that both end edges are engaged with each other. The direct cooling power cable according to claim 1, wherein 4. The direct cooling power cable according to claim 1, wherein the flexible metal tube (7) has a rectangular cross section.