JP3144990B2 - Conductor structure of oxide superconducting 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 an oxide superconducting conductor and an oxide superconducting power cable which are being developed for use in power transport or superconducting magnets.

[0002]

2. Description of the Related Art Conventionally, attempts have been made to manufacture a power cable for power transport, a superconducting magnet or a superconducting power cable for a field winding of a superconducting generator using an oxide superconducting conductor having a high critical temperature. I have. As a conventional example of such a superconducting conductor, as shown in FIG.
A plurality of long oxide-based superconducting tape units 1 (FIG. 1)
A superconducting conductor 3 is known in which 16 (in the example of FIG. 1) are fixed by soldering so as to be spirally disposed adjacent to a pipe 2 made of copper or the like. As shown in FIG. 10, the superconducting tape unit 1 of the superconducting conductor 3 includes a superconducting tape 6 formed by covering an oxide superconducting core 4 with a soft metal sheath 5 made of silver or the like. It is formed by laminating and integrating a plurality of metal adhesives.
In the superconducting conductor 3 having the structure shown in FIG. 11, liquid nitrogen is allowed to flow as a refrigerant inside the central pipe 2, and the surrounding oxide superconducting core 4 is cooled by the liquid nitrogen.

Conventionally, in order to manufacture a superconducting conductor 3 having a structure shown in FIG. 11, a plurality of superconducting tapes 6 are laminated to form one superconducting tape unit 1, and a plurality of superconducting tape units 1 are prepared. Each of them is wound spirally around the outer peripheral surface of the pipe 2 and then fixed by soldering. However, when the superconducting conductor 3 is manufactured by this method, the superconducting tape unit 1 is wound while being directly bent, so that the individual superconducting tapes 6 are easily distorted, and depending on the winding method, the superconducting tape 6 is locally applied to the superconducting tape 6. There is a problem that large distortion is easily added. That is, the oxide superconducting core 4 is made of Bi ₂ Sr ₂ Ca ₂ Cu
₃ O _x , Bi ₂ Sr ₂ Ca ₁ Cu ₂ O _y , Bi _1.6 Pb _0.4 Sr ₂
Ca ₂ Cu ₃ O _x , Tl ₂ Ba ₂ Ca ₂ Cu ₃ O _y , Tl ₂ Ba ₂
Since it is a ceramic having a composition represented by Ca ₁ Cu ₂ O _y or Y ₁ Ba ₂ Cu ₃ O _x , it has brittleness as a ceramic and is extremely resistant to bending force and tensile force. There is a weak problem. Further, since the sheath 5 made of silver is very soft, there is a problem that the oxide superconducting core 4 is easily damaged by a small external force.

Next, the plurality of superconducting tape units 1
Are sequentially wound around the pipe 2 and fixed one by one by soldering, the solder that has fixed the superconducting tape 6 that has already been soldered is re-melted by the heat when the other superconducting tape 6 is soldered, and The attached superconducting tapes 6 may peel off. Further, when a plurality of superconducting tape units 1 are sequentially fixed by soldering, there is a problem that it is difficult to simultaneously fix the entire superconducting tape unit 1 at an accurate position.

Next, in order to manufacture a superconducting power cable using the superconducting conductor 3 having the structure shown in FIG. 11, a copper tape or a semiconducting tape (e.g., carbon tape) on the superconducting conductor 3 for making the electric field uniform is used. It is conceivable to manufacture the tape by winding the necessary tape in order, for example, by winding an electrical insulating tape thereon. Therefore, in the superconducting tape 6 of the superconducting tape unit 1, another member is wound around the outside, and there is a possibility that the member may be damaged due to an external injury during handling during winding. There is a problem that characteristics are likely to deteriorate. That is, since each superconducting tape 6 is fixed to the outer peripheral portion of the tubular body 2 as a bare conductor, there is a problem that the superconducting tape 6 is easily damaged.

[0006] From such a background, the present inventors have developed a superconducting power cable having a novel structure capable of solving these problems, and the superconducting power cable has been developed in June 1993.
A patent application was filed in Japanese Patent Application No. 5-150907 on May 22. The superconducting power cable according to this patent application comprises a superconducting tape unit comprising a plurality of superconducting tapes each including an oxide superconducting core inside a tape-shaped sheath made of a conductive metal material, which are laminated and fixed to each other. A plurality of spiral grooves are formed on at least one of the outer peripheral surface and the inner peripheral surface of the tube made of a metal material, and a forward path of the refrigerant is formed inside to form a central tube, and each spiral groove of the central tube is formed. The superconducting tape unit is loosely inserted in an unfixed state, and further provided with an inner shielding layer provided on the outer surface of the central tube, and an outer coating layer provided on the outer surface thereof through a spacer. A return path for the refrigerant was formed between the layers. According to this structure, the superconducting tape unit is accommodated in the spiral groove so as to be able to be slightly displaced in the length direction to prevent the application of stress and strain, to prevent the deterioration of superconducting characteristics, and to increase the power capacity. Had excellent features that could be.

[0007]

However, in the superconducting cable having the above structure, the center tube having the spiral groove is formed of a good conductive metal material such as Cu, so that it has high rigidity and is difficult to bend. was there. Such a structure in which the superconducting cable is difficult to bend may hinder the formation of the superconducting coil by winding it around a winding drum or the like. Unnecessary strain is added to the body and the superconducting tape unit inside the body, and the superconducting properties may be impaired. In addition, there is a problem in that the superconducting cable becomes heavier by the weight of the provision of the central tube.

The present invention has been made in view of the above-mentioned circumstances, and does not give a distortion to the superconducting tape as compared with the conventional method in which each superconducting tape unit is fixed to the outer peripheral surface of the tubular body. Oxide superconductor that can be easily wound and fixed, has less risk of deterioration of superconducting characteristics, can be bent more easily and lighter than the previously proposed structure, and can adjust the bending angle and can bend uniformly An object is to provide a conductor structure of a power cable.

[0009]

According to a first aspect of the present invention, in order to solve the above-mentioned problems, a plurality of spiral grooves are formed on at least one of an outer peripheral surface and an inner peripheral surface in a tubular shape made of a conductive metal material. Along with forming a flow path of the refrigerant inside to form a central tube, a plurality of superconducting tapes having an oxide superconducting core inside a tape-shaped sheath made of a conductive metal material are laminated and fixed to each other. A superconducting tape unit is formed, and while the superconducting tape unit is loosely inserted into each spiral groove of the central tube in a non-fixed state, a spiral formed on at least one of the outer peripheral surface and the inner peripheral surface of the central tube is formed. A spiral ridge is formed on at least one of the outer peripheral surface and the inner peripheral surface of the central tubular body by the groove, and a plurality of annular cut grooves surrounding the entire circumference of the central tubular body are formed on the upper surface of the spiral ridge over the entire length of the central tubular body. What is formed A.

According to a second aspect of the present invention, in order to solve the above-mentioned problem, the cut groove according to the first aspect is formed in a V-shape including two inclined surfaces, and these inclined surfaces are maximum when the central tube is curved. It is a regulation surface that defines the curvature.

According to a third aspect of the present invention, in order to solve the above-mentioned problem, the cut groove according to the first or second aspect is provided by connecting spiral grooves adjacent to each other in the circumferential direction of the central tube. .

According to a fourth aspect of the present invention, in order to solve the above-mentioned problem, an outer surface of the central tube is coated with an inner shielding layer, and an outer coating layer is provided on the outer side thereof with a spacer interposed therebetween to form an inner shielding layer. A coolant flow path is formed between the coating layers, and a coolant circulation path is formed by the coolant flow path and the coolant flow path inside the central tube.

[0013]

[Function] The superconducting tape unit is housed in the spiral groove of the central tube, and the superconducting tape unit is spirally wound around the central tube. The tape unit can be cooled and the oxide superconducting core of the superconducting tape unit can be brought into a superconducting state and used for energization. Further, since a plurality of superconducting tape units are provided for one central tube, the current capacity can be increased.

Since the superconducting tape unit is loosely inserted into the spiral groove on the outer surface of the central tube, other members such as a shielding layer wound outside the central tube do not contact the superconducting tape unit. Configuration. Therefore, the superconducting tape unit is not damaged by other members during the production of the superconducting power cable, and the superconducting characteristics do not deteriorate.
Also, even if a bending force is applied to the superconducting power cable during installation, etc., the superconducting tape unit can move slightly in the spiral groove of the central tube, so stress and strain may concentrate on a part of the superconducting tape unit. Few. When one or more superconducting tape units housed in the plurality of spiral grooves of the central tube cause a deterioration in superconducting characteristics due to any cause, the superconducting tape units are replaced with the central tube. It is also possible to pull it out and exchange it for a new one.

Since a plurality of annular cut grooves surrounding the entire periphery of the central tube are provided over the entire length of the central tube, the central tube can be easily bent starting from the cut grooves, and the central tube can bend. The bendability is improved, resulting in a flexible structure. Further, the weight of the central pipe is reduced by the amount of the cut grooves. Further, in the case where the inner wall of the cut groove has an outwardly inclined surface, the inclined surface of the cut groove on the peripheral side of the central tube abuts on the inner peripheral surface of the central tube by bending the central tube, thereby restricting the amount of bending. The maximum bending amount can be obtained according to the angle of the inclined surface of the groove, and the bending angle of the superconducting cable can be adjusted by adjusting the angle of inclination of the inclined surface of the cut groove. Done.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a first example of an oxide superconducting power cable according to the present invention. A superconducting power cable 10 of this example has a central tube 11 at the center and various coatings are applied to the outside thereof. It is configured. The central tube 11 has a plurality of spiral grooves 11a (ten in the case of the present embodiment) formed on the outer periphery of a tube made of a highly conductive metal material such as copper or aluminum. The outward path 13 is configured so that a refrigerant such as liquid nitrogen flows through the refrigerant outward path 13.

Helical groove 11a at the outer periphery of the central tube 11
Are formed between the spiral ridges 11b.
1b, the peripheral surface of the central tubular body 11 constituted by the upper surface
As shown in FIG. 2, a large number of annular cut grooves 11 c surrounding the entire periphery of the central tube 11 are formed at predetermined intervals over the entire length of the central tube 11. In this example, an inner surface portion of the cut groove 11c is formed in a V-shape constituted by inclined surfaces 11d, 11d inclined with respect to the upper surface of the spiral ridge 11b. Since the cut groove 11c is an annular groove formed on the entire circumference of the central pipe 11, the spiral grooves 11a, 11a adjacent to the central pipe 11 in the circumferential direction are cut grooves 11a.
and are communicated with each other via a. This cut groove 1c
May be formed by cutting the outer peripheral surface of the central tube 11 with a cutting tool or the like, or may be formed by another method such as plastic working. The inclined surface 11d may be configured to intersect at right angles with the upper surface of the spiral ridge 11b as shown by a chain line 11e in FIG.

In each of the spiral grooves 11a, a superconducting tape unit 15 is provided with a slight play.
It is inserted so that it does not protrude. By providing the superconducting tape unit 13 so as not to protrude from the spiral groove 11a, the risk of damaging the superconducting tape unit 15 by winding another member around the outside of the central conductor 1 as described later is reduced. As shown in FIG. 4, the superconducting tape unit 15 is formed by laminating a plurality of superconducting tapes 16 and fixing them to each other with a metal adhesive such as solder. The superconducting tape 16 is made of a Y-Ba-Cu-O-based, Bi-Pb-Sr-Ca
A tape-shaped superconducting core 17 made of an oxide superconductor represented by -Cu-O, Tl-Ba-Ca-Cu-O or the like is covered with a sheath 18 made of a noble metal such as silver. In the above Y-Ba-Cu-O-based oxide superconductor, Nd, Eu, Dy, Er, Y
One or more rare earth elements such as b may be used.

The superconducting tape unit 15 is not fixed in the spiral groove 11a by solder or the like. This is because, when the superconducting tape unit 15 is fixed in the spiral groove by soldering, the superconducting tape unit 15 is directly affected by an external force such as expansion and contraction transmitted to the central tube 11, and the superconducting tape unit 15 Is deteriorated. That is, when an external force acts on the central tube 11, even if the central tube 11 expands and contracts, the superconducting tape unit 15 can behave independently in the length direction of the central tube 11, so that elongation and strain are added. As a result, deterioration of superconducting characteristics is reduced. Also, the superconducting tape unit 1
When 5 is loosely inserted in the spiral groove 11a with some play, the superconducting tape unit 15 is directly cooled by the refrigerant due to the permeation of the refrigerant from the outer refrigerant return path 28 described later.

Next, outside the central tube 11, an inner shielding layer 20, an insulating layer 21, and an outer shielding layer 22 are sequentially coated, and further outside the outer shielding layer 22, a separator 23 is provided.
, A coating layer 29 composed of an inner protection pipe 24, a heat insulating layer 25, an outer protection pipe 26, and an anticorrosion layer 27 is sequentially arranged. It is preferable that the inner protection pipe 24 and the outer protection pipe 26 have a corrugated shape in order to ensure flexibility. The inner shielding layer 20 includes a copper tape 20a wound around the outer surface of the central tube 11, and a semiconductive layer 22b formed by winding a carbon tape or the like outside the copper tape 20a. Shielding layer 2
Numeral 2 includes a semiconductive layer 22a formed by winding a carbon tape or the like around the insulating layer 21 and a copper tape 22b wound outside the semiconductive layer 22a. The insulating layer 21 is made of kraft paper or synthetic paper (polypropylene laminated paper: PPLP) or the like, and is provided to ensure a dielectric strength. Since the electric insulating layer 21 is formed by winding an insulating tape, the liquid nitrogen of the refrigerant flowing through a refrigerant return path 28 described later on the outside of the electric insulating layer 21 penetrates into this portion via the semiconductive layer 22a. It contributes to the improvement of insulation properties.

Outside the inner shielding layer 20, a refrigerant return path (flow path) 28 is defined by the inner shielding layer 20, the separator 23 and the outer shielding layer 22. The refrigerant return path 28 is a flow path through which a refrigerant such as liquid nitrogen flows,
One end of the superconducting power cable 10 connects the refrigerant return path 28 to the refrigerant outward path 13 inside the central pipe 11, and the other end connects the refrigerant outward path 13 and the refrigerant return path 28 to a refrigerant supply source such as liquid nitrogen (not shown). To supply refrigerant to the refrigerant outward path 13 from this refrigerant supply source and return the refrigerant through the refrigerant return path 28, so that the refrigerant can circulate over the entire length of the superconducting power cable 10.

The separator 23 is wound around the outside of the outer shielding layer 22 and is provided for forming a refrigerant outward path 28 between the outer shielding layer 22 and the inner protection pipe 24 outside the outer shielding layer 22. ing. Note that this separator 23
Is from a stainless steel metal wire or CBN,
Ceramics such as Al ₂ O ₃ and partially stabilized zirconia,
Alternatively, polytetrafluoroethylene (Teflon),
A linear body or a strip made of a synthetic resin such as polyethylene or nylon may be used. The inner protective tube 24 and the outer protective tube 26 are made of stainless steel, aluminum, or the like. In this example, the inner protective tube 24 and the outer protective tube 26 are corrugated in order to ensure flexibility, and the anticorrosion layer 2 is formed.
Numeral 7 is a resin coating layer for anticorrosion. The inner protective pipe 24 is made of a metal material such as stainless steel having a thickness of about 1.5 to 2 mm, and the heat insulating layer 25 is formed by winding a super insulative or the like and having a thickness of about 10 to 20 mm. It is.

In order to manufacture the superconducting power cable 10, first, one or a plurality of superconducting tapes 16 are laminated, and a necessary portion in the longitudinal direction is fixed with solder to form a superconducting tape unit 15. Then, a plurality of the superconducting tape units 15 are prepared, and
It is individually wound along one spiral groove 11a. Next, a copper tape 22a and a semiconductive tape are sequentially wound around the center tube body 11 to form an internal shielding layer 20, and an insulating tape is wound thereon to form an insulating layer 21. Subsequently, a semiconductive tape and a copper tape 22b are wrapped thereon to form an outer shielding layer 22, a required number of separators 23 are wrapped around the outer shielding layer 22, and an inner protective pipe 24 is further wrapped over the outer wrapping, and a super insulation is performed. The heat insulating layer 25 is formed by winding, and finally the outer protective pipe 26 is covered to form the anticorrosion layer 27, thereby obtaining the oxide superconducting power cable 10 shown in FIG.

Next, a case where the oxide superconducting power cable 10 having the above structure is used will be described. The superconducting power cable 10 circulates a refrigerant such as liquid nitrogen through the refrigerant outward path 13 and the refrigerant return path 28 to cool the superconducting tape units 15... And displaces the superconducting core 17 of the superconducting tape unit 15 to the superconducting state. To use for energization. In this case, the superconducting core 17 can be cooled by the refrigerant in the refrigerant outward path 13, so that the stability of the superconducting core 17 can be ensured when energized in the superconducting state.

Further, since the outer shielding layer 22, the insulating layer 21, and the inner shielding layer 20 are all formed by winding a tape, the liquid nitrogen of the refrigerant flowing through the refrigerant return path 28 outside the tape is wound around the tape. The superconducting tape units 15 are directly cooled by penetrating into the superconducting tape unit 15 inside the spiral groove 11a from the gap. Further, since the spiral grooves 11a are communicated with each other by the cut grooves 11c, the refrigerant flows through the cut grooves 11c to efficiently cool the superconducting tape units 15. Here, the insulating layer 21 impregnated with the liquid nitrogen has an improved withstand voltage, so that the withstand voltage of the superconducting power cable 10 can be improved. Furthermore, the spiral groove 11
Since the refrigerant flowing into a can move to the other spiral groove 11a via the cut groove 1c, the refrigerant can spread to any spiral groove 1a, and the cooling efficiency is improved. In addition,
When the superconducting tape unit 15 shifts to the normal conducting state for some reason while the superconducting power cable 10 is energized, it is necessary to temporarily release the large power supplied from the power supply source. In such a case, in the superconducting power cable 10 having the above-mentioned structure, the central tube 11 serves as a grounding conductor for ground fault for releasing the current.

FIG. 5 shows a second example of the central tube.
The center tube 11 'of this embodiment differs from the center tube 11 of the first embodiment shown in FIG. 3 in that a round portion 11f is formed at the bottom of the cut groove 11c'. Other configurations are the same as the central tube 11 of the previous example. By providing the round portion 11f at the bottom of the cut groove 11c 'in this manner, the flexibility of the central tube 11' is improved, and the central tube 1 '
When 1 'is bent for coil processing etc., the central tube 1
There is no possibility that a crack originating from the bottom of the cut groove 11c may be formed in 1 '. FIG. 6 shows a third example of the central tube. The central tube 11 '' of this example differs from the central tube 11 of the first example shown in FIG.
11g whose inner surface is oriented perpendicular to the outer surface of the central tube 11 ''
The point is that a round portion 11i is formed at the bottom of the cut groove. Other configurations are the same as the central tube 11 of the previous example. With this configuration, the cut groove 11c ″ can be formed when bent for coil processing or the like as in the previous example.
The crack starting from the bottom of the center tube 11 ″ can be prevented from being generated.

FIG. 7 shows an example of a central tube used in the second embodiment of the present invention.
A plurality of through-holes 41, 42,... Are formed in the radial direction of the central tube body 40, and the superconducting power cable 10 'is provided with these. The through-holes 41...
0 and an inner bottom surface of the spiral groove 43.
The other through-holes 42 open on the inner peripheral surface of the central tube 40 and the outer peripheral surface of the central tube 40. With the above-described structure, the refrigerant flowing through the refrigerant outward path 44 inside the central tube 40 can be guided to the superconducting tape unit 15 through the through holes 41... And 42. 15 can be cooled. At this time, the through hole 4
1 pass directly to the superconducting tape unit 15 and cool it, and the refrigerant passing through the through holes 42 seeps out around the superconducting tape unit 15 and cools the superconducting tape unit 15 from the surrounding side. I do. By forming the through holes 41 and 42, the weight of the central tube 40 can be further reduced.

FIG. 8 shows an example of a central tube used in the third embodiment of the present invention. In this central tube 45, a plurality of spiral grooves 46 are formed on the peripheral surface of the tube. The superconducting tape unit 15 is housed inside the spiral groove 46 of the above-mentioned structure to constitute the superconducting power cable 10 ″.
In this example, a cut groove is formed on the inner surface side of the central tube 45. With such a structure, there is a feature that the superconducting tape unit 15 can be directly cooled by the refrigerant flowing through the refrigerant outward path 47 inside the central pipe 45.

FIG. 9 shows an oxide superconducting power cable 50 according to a fourth embodiment of the present invention. In the superconducting power cable 50, a superconducting tape is wound around the superconducting power cable 10 in place of the copper tape 22b of the outer shielding layer 22 in the superconducting power cable 10, and the superconducting shield layer 51 is provided. The superconducting shield layer 51 has a thickness of 0.1 to 1 on a metal tape base material such as Hastelloy tape.
A superconducting tape on which a thin-film superconducting layer such as a Y-Ba-Cu-O system of about μm is wound, or
Superconducting tape 1 constituting said oxide superconducting conductor 10
6 is wound. Here, in order to form a superconducting layer on the metal tape substrate, a film forming method such as a laser vapor deposition method, a CVD method (chemical vapor method), and an MBE method (molecular beam epitaxy method) may be performed. Further, a thickness of 5 mm is formed on the metal tape substrate by a doctor blade method.
A superconducting tape may be formed by applying a thick film having a thickness of about 50 μm and heat-treating it in an oxygen stream to form a superconducting layer in the form of a thick film such as a Y—Ba—Cu—O system.

At the time of this winding, it is preferable to wind the superconducting tape with the metal tape substrate facing outward and the superconducting layer facing inside. Thereby, when the superconducting power cable 50 is used for alternating current, eddy current loss generated at the time of alternating current using the metal tape base material of the normal conducting portion can be reduced, and the superconducting power cable 50 can be laid out. Even in the case of performing, the deterioration of the superconducting characteristics of the superconducting layer can be reduced.

As a preferred example of the superconducting shield layer 51, YS is applied on the inner surface of a metal tape base made of a Ni-based alloy such as Hastelloy or a stainless tape.
Examples include an intermediate layer made of Z (yttrium-stabilized zirconia), MgO or SrTiO ₃ and a superconducting thin film formed thereon. By adopting this structure, deterioration of the superconductivity can be prevented as described above,
A desired magnetic shielding effect can be obtained.

The superconducting shield layer 51 has a function of repelling the magnetic field generated by the superconducting core 17 due to the Meissner effect when the superconducting core 17 is energized. In particular, if an alternating magnetic field acts when AC current is applied, AC loss may occur, and this can be prevented by the superconducting shield layer 51.

[0033]

EXAMPLE Bi: Pb: Sr: Ca: Cu = 1.8: 0.
Bi ₂ O so that the composition ratio is 4: 2.0: 2.2: 3.0.
₃ , powders of PbO, CuO, SrCO ₃ , and CaCO ₃ were blended and calcined at 800 to 840 ° C. for 74 hours four times in the atmosphere to obtain a calcined powder. The calcined powder was formed by an isostatic press, inserted into a silver pipe having an outer diameter of 40 mm and a thickness of 2.5 mm, and subjected to cold working until the diameter became 2.4 mm. Thereafter, rolling and heat treatment at 830 to 840 ° C. × 50 hours are repeatedly performed three times to finally achieve a thickness of 0.1 m.
A silver sheath Bi-based tape having a mx 4.0 mm width was obtained. Forty-five sheets of this silver sheath Bi-based tape were stacked and fixed by soldering to produce a superconducting tape unit having a width of 4.2 mm and a height of 4.8 mm. When this superconducting tape unit was cooled with liquid nitrogen and energized under the condition of an external magnetic field of 0 T, 225 A was able to flow.

As the central tube, the outer diameter a of the tube portion shown in FIG. 3 is 29 mm, the inner diameter b is 20 mm, the height c of the spiral ridge is 5.5 mm, and the width d of the surface of the spiral ridge is d. 3mm,
An aluminum pipe with an opening of the cut groove having a width of 2 mm and a length of 10 m was used, and a rectangular cross-sectional spiral groove having a width of 6 mm and a depth of 5.5 mm every 36 degrees (spiral pitch 1 m) was provided on the outer periphery thereof. Were formed to form a central tube. The superconducting tape unit was inserted into each of the spiral grooves to obtain a central tube. 0.1mm thick on this central tube
And a semiconductive tape containing carbon was further wound to form an inner shielding layer, and kraft paper was wound thereon to form an insulating layer. At this time, the thickness of the insulating layer was set to 6 to 7 mm, and the structure was made to withstand the electrical insulation of 70,000 V. Then, a semiconductive tape and a copper tape having a thickness of 0.1 mm were wound on the insulating layer to obtain a DC cable.

Next, several wires made of polytetrafluoroethylene (Teflon) having a diameter of 5 mm are wound on the copper tape, and further inserted into an inner protective pipe made of stainless steel having an outer diameter of 82 mm and an inner diameter of 75 mm. It was processed to have an outer diameter of 82 mm and an inner diameter of 65 mm. The inside of this internal protection pipe becomes the refrigerant return path. Furthermore, super insulation is wrapped around the inner protective pipe, an outer protective pipe made of stainless steel is put on the outside, corrugated, and the outer side is subjected to vinyl corrosion protection, and the outer diameter is 120 m.
m of superconducting power cable was obtained.

With respect to this superconducting power cable, liquid nitrogen was circulated using the refrigerant outward path and the refrigerant return path inside the central tube, the whole was cooled to 77 K, and an energization test was performed in an external magnetic field of 0T. As a result, it was possible to flow 2200A having a value close to 10 times the value of 225A obtained in the superconducting tape unit through the superconducting power cable. Therefore, when ten superconducting tape units were collectively formed into a cable, deterioration of superconducting characteristics was hardly observed. Also, when the dielectric strength of the superconducting power cable was measured, it was 80 kV before flowing the liquid nitrogen refrigerant, but was changed to 100 kV after flowing the liquid nitrogen.
Improved. This is because liquid nitrogen used as refrigerant
It is thought to be due to the result of soaking into the insulating layer. Also,
When this superconducting power cable was wound around a winding drum having a diameter of 3 m and an energization test was performed, an energization of 2200 A was possible. Moreover, the winding process when wound around the winding drum could be performed smoothly.

For comparison, an ordinary tube having no spiral groove was used in place of the center tube, ten superconducting tape units were spirally wound around the tube, and they were fixed by soldering. Basically, a superconducting power cable having the same coating layer as described above was manufactured. However, this superconducting power cable was capable of conducting a current of 1000 A, and a deterioration phenomenon of superconductivity was observed. This is probably because the superconducting tape unit was distorted or added due to handling when the superconducting tape unit was wound around the outer periphery of the tube and soldered. Also, when a copper tape or the like is wound around the outside of the superconducting tape unit, it is considered that the superconducting tape unit is subjected to addition or distortion. Further, when the superconducting power cable was wound around a winding drum having the same size as that described above and an energization test was performed, it was only possible to energize at 600 A, and the superconductivity was further deteriorated. This is thought to be due to the fact that the central tube was unevenly curved when the superconducting power cable was wound around the winding drum, and as a result, distortion was partially applied to the superconducting tape unit.

[0038]

As described above, according to the present invention, since the superconducting tape unit is housed in the spiral groove on the outer periphery of the central tube, the superconducting tape unit is formed by flowing a refrigerant such as liquid nitrogen into the tube. It can be cooled and the superconducting core in the superconducting tape unit can be put into a superconducting state and used for energization. Further, since a plurality of superconducting tape units are wound around one central tube, the power capacity can be increased.

Next, since a plurality of annular cut grooves surrounding the entire circumference of the central pipe are provided over the entire length of the central pipe, the central pipe can be easily bent starting from the cut grooves. The flexibility of the body is improved, resulting in a structure that is more flexible than the structure to which the present inventors previously applied for a patent. Therefore, when the superconducting coil is wound around the winding drum, the coil can be easily processed, and the central tube can be bent starting from a plurality of cut grooves. The bent portion can be prevented from being generated, and the superconducting tape unit is not partially subjected to excessive strain. Also,
The weight of the superconducting power cable can be reduced because the central tube is reduced in weight by the provision of the cut grooves.

Further, in the case where the inner wall of the cut groove has an outwardly inclined surface, by bending the central tube, the inclined surfaces of the cut grooves on the peripheral side of the central tube contact each other to regulate the amount of bending. Therefore, the maximum amount of bending can be obtained according to the angle of the inclined surface of the cut groove, and the bending angle of the superconducting cable can be adjusted by adjusting the inclination angle of the inclined surface of the cut groove. Furthermore, since the superconducting tape unit is housed in the spiral groove of the central tube in an unfixed state, an external force caused by a force applied at the time of manufacturing or a bending acting upon coil processing acts on the superconducting tape unit. If this is attempted, the superconducting tape unit retains its independence in the spiral groove and can be slightly displaced in the spiral groove. The configuration is unlikely to occur.

By inserting the superconducting tape unit into the spiral groove, the arrangement of the superconducting tape unit is completed, so that the soldered portion of the superconducting tape unit is not re-melted. Therefore, the superconducting tape does not peel off from the tape base material when the superconducting tape unit is attached. Further, in the oxide superconducting power cable of the present invention, in which the refrigerant flow path inside the pipe and the refrigerant flow path outside the pipe are provided, the refrigerant passage inside the pipe is used as the outward path of the refrigerant, and the outside of the pipe is used. Can be used as the return path of the refrigerant, and the circulation path of the refrigerant can be formed, so that the refrigerant can be circulated, the superconducting tape unit can be efficiently cooled, and the superconducting characteristics can be stabilized. I do. In addition, since the cut groove communicates with the spiral groove that houses the superconducting tape unit, refrigerant can flow between adjacent spiral grooves through the cut groove, improving the cooling efficiency of the refrigerant and stabilizing the superconducting characteristics. it can.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first example of a superconducting power cable according to the present invention.

FIG. 2 is a perspective view showing a central tube applied to the superconducting power cable shown in FIG.

FIG. 3 is an enlarged sectional view showing a part of a central tube shown in FIG. 2;

FIG. 4 is a cross-sectional view showing a state where a superconducting tape unit is housed in a central tube shown in FIG.

FIG. 5 is a sectional view showing a second example of the central tube.

FIG. 6 is a sectional view showing a third example of the central tube.

FIG. 7 is a sectional view showing a second example of the superconducting power cable according to the present invention.

FIG. 8 is a sectional view showing a third example of the superconducting power cable according to the present invention.

FIG. 9 is a sectional view showing a fourth example of the superconducting power cable according to the present invention.

FIG. 10 is a perspective view showing a tape unit provided in a conventional superconducting power cable.

FIG. 11 is a sectional view showing an example of a conventional superconducting power cable.

[Explanation of symbols]

10, 10 ', 10'', 50 ... superconducting power cable, 1
1, 40, 45 ... central tube, 11a, 43, 46
..Spiral groove, 11b ... spiral ridge, 11c, 11c ', 11
c '': notched groove, 11d: inclined surface, 11f, 11
i ... R part, 11g ... Inner surface, 15 ... Superconducting tape unit, 16 ... Superconducting tape unit,
17 ... superconducting core, 18 ... sheath,

Continuing from the front page (72) Inventor Satoshi Kono 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Inventor Nobuyuki 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Co., Ltd. ( 72) Inventor Shigeo Nagaya 20-1, Kita-Sekiyama, Odaka-cho, Midori-ku, Nagoya-city, Aichi Prefecture Inside the Electric Power Research Laboratory, Chubu Electric Power Co., Inc. (72) Inventor Naoki Hirano, Odaka-cho, Midori-ku, Nagoya-shi, Aichi Prefecture 20 Sekiyama 1 Chubu Electric Power Co., Inc. Power Technology Research Institute (56) References JP-A-5-81941 (JP, A) JP-A-6-44832 (JP, A) JP-A 5-135630 (JP) , A) JP-A-7-14443 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 12/00-13/00

Claims (4)

(57) [Claims] 1. A central tube is formed by forming a plurality of spiral grooves on at least one of an outer peripheral surface and an inner peripheral surface and forming a flow path of a refrigerant therein, the central tube being formed of a conductive metal material. A plurality of superconducting tapes each having an oxide superconducting core are laminated inside a tape-shaped sheath made of a conductive metal material and fixed to each other to form a superconducting tape unit.The superconducting tape unit is formed in each spiral groove of the central tube. While the superconducting tape unit is loosely inserted in a non-fixed state, a spiral groove is formed on at least one of the outer peripheral surface and the inner peripheral surface of the central tubular body by a spiral groove formed on at least one of the outer peripheral surface and the inner peripheral surface of the central tubular body. A conductor structure of an oxide superconducting power cable, characterized in that a plurality of annular cut grooves surrounding the central tube are formed on the upper surface of the spiral ridge over the entire length of the central tube. 2. The inner surface of the cut groove has a V
2. The conductor structure for an oxide-based superconducting power cable according to claim 1, wherein the conductor structure is formed in a shape of a letter, and these inclined surfaces are formed as regulating surfaces that define the maximum curvature when the central tube is curved. 3. The conductor structure of an oxide superconducting power cable according to claim 1, wherein the cut grooves are provided so as to communicate with spiral grooves adjacent in the circumferential direction of the central tube. 4. An outer surface of the central tube is coated with an inner shielding layer, and an outer coating layer is provided on the outer surface thereof with a spacer interposed therebetween, so that a coolant flow path is formed between the inner shielding layer and the outer coating layer. 4. The conductor structure for an oxide superconducting power cable according to claim 1, wherein a refrigerant circulation path is formed from the refrigerant flow path and the refrigerant flow path inside the central tube.