JPH06187849A - High-temperature superconducting cable - Google Patents

Abstract

PURPOSE:To provide a high-temperature superconducting cable having a sufficient critical current for an alternating current to be transmitted. CONSTITUTION:A high-temperature superconducting cable comprises a conductor layer 3 provided around the outer periphery of a former 2 having a refrigerant passage 1 therein and a magnetic shielding conductor layer 5 provided on the outside of the layer 3 with an electrical insulator 4 therebetween. The conductor layer 3 is formed by using a high-temperature superconducting multicore tape 8 comprising a number of thin high-temperature superconductors 7 stacked one atop another and twisted together. Also, the numerous tapes 8 are arranged in the circumferential direction and spirally wound while the side faces 9 of adjacent tapes 8 are butted. The high-temperature superconducting multicore tape 8 is used also in the magnetic shielding conductor layer 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to an AC high temperature superconducting cable using a high temperature superconductor as a conductor, and can be used as a core of an AC high temperature superconducting cable for transmitting an alternating current from a very low frequency to a commercial frequency.

[0002]

2. Description of the Related Art Conventionally, cables for AC transmission have been available. An example is shown in FIG. 3A, which is for three-layer AC transmission. This is because the energizing core D is provided inside the refrigerant passage C for flowing the cryogenic refrigerant inside the heat insulating layer B of the heat insulating pipe A.
3 are stored (for 3 phases).

As shown in FIG. 3 (b), the energizing core D has an energizing conductor layer G wound around the outer periphery of a former F having a coolant passage E, and an electrical insulator H interposed outside the former. An electric wire provided with the magnetic shield conductor I is used.
The current-carrying conductor layer G was formed by laminating a plurality of tapes J as shown in FIG. This tape J is a composite plate in which a metal superconductor L such as niobium or niobium titanium is bonded onto a substrate K made of a stabilizing material such as copper by explosive deposition, and the composite plate is rolled to a required thickness and then the required thickness is obtained. It is cut into width.

By the way, since the high-temperature superconductor is an oxide unlike the conventional metal superconductor, it is impossible to form a composite with the stabilizing material K by the above-mentioned explosive deposition. There is a method such as plasma spraying as a method of compounding an oxide and a metal, but even when plasma spraying a high-temperature superconductor on a metal plate, the superconducting current of the superconducting current is generated due to microscopic cracks and voids present in the sprayed film. There has been a problem that the flow path is severely divided and a superconducting tape having a large critical current cannot be obtained.

Therefore, conventionally, as a composite method of a high temperature superconductor and a metal, a high temperature superconducting material is filled in a silver pipe,
A method is generally employed in which the high temperature superconducting material is made to exhibit superconducting properties by being extruded to make it into a thin wire, rolled into a tape, and further sintered at about 850 ° C.

Further, since the high temperature superconductor is an oxide and is vulnerable to bending strain, for the purpose of reducing the bending strain applied to the high temperature superconducting conductor in the wire, a very thin high temperature superconducting film is contained in one tape. A high-temperature superconducting multi-core tape (ultra-thin multi-core superconducting tape) having a structure in which a large number of conductors are laminated has been used.

[0007]

Such a high temperature superconducting multifilamentary tape is sufficient as it is for use as a direct current energizer. However, energizing an alternating current at a commercial frequency level has the following problems. It was ． When a high-temperature superconducting multi-core tape is energized with alternating current, an alternating current begins to flow from the superconducting conductor in the outer layer, but due to the impedance difference between the superconducting conductor in the outer layer and the inner layer, the alternating current does not flow completely to the superconducting conductor in the inner layer. There was a problem. ． Even when the high-temperature superconducting multi-core tapes are laminated in a circumferential shape as described above, there is a problem that an alternating current does not completely flow to the inner superconducting tape due to the difference in impedance between the outer and inner superconducting tapes.

Therefore, it has been conventionally desired to further devise and improve the high temperature superconducting multi-core tape. The present invention was developed in order to solve the above problems of a high temperature superconducting multifilamentary tape, and its object is the structure of the high temperature superconducting multifilamentary tape itself,
The purpose of the invention is to provide a high-temperature superconducting cable having a sufficient critical current with respect to AC energization by devising the structure when it is used as an energizing conductor layer.

[0009]

In order to solve the above problems, the present inventor has conducted various studies on the core for an AC high temperature superconducting cable, and has obtained the following findings. That is, in order that the high-temperature superconducting multi-core tape and the conducting layer for energization using a plurality of the same have a sufficient critical current with respect to the alternating current, many of the high-temperature super-conducting multi-core tapes are laminated. It is necessary to make the impedances of the respective layers of the superconducting conductor substantially the same. In other words, it is a necessary condition that many layers of superconducting conductors have the same arrangement as much as possible, and that the superconducting conductors of all layers have the same geometrical arrangement when they are used as current-carrying conductor layers. . The high temperature superconducting cable of the present invention was developed to satisfy this requirement as much as possible.

The high-temperature superconducting cable according to the first invention of the present application is a high-temperature superconducting cable in which a conducting layer 3 made of a plurality of superconducting multi-core tapes 8 is provided on the outer periphery of a former 2, wherein the superconducting multi-core tape 8 is A plurality of high temperature superconducting conductors 7 are provided in the stabilizer 6 in a twisted arrangement.

In the high temperature superconducting cable of the second invention of the present application, a conductor 2 for energization consisting of a plurality of superconducting multi-core tapes 8 is provided on the outer periphery of the former 2, and a plurality of superconducting multi-core tapes are spaced apart on the outer periphery thereof. In a high temperature superconducting cable provided with a magnetic shield conductor layer 5 made of 8, the superconducting multi-core tape 8 is provided in the stabilizing material 6 in a twisted arrangement of a plurality of high temperature superconducting conductors 7. It is characterized by.

[0012]

In the high temperature superconducting cable of the first invention, the high temperature superconducting conductor 7 of each high temperature superconducting multi-core tape 8 is twisted. Located elsewhere on the outside. Therefore, the geometrical arrangement of the outer periphery of the former 2 is almost the same for all the high temperature superconducting conductors 7. As a result, the impedances of all the high-temperature superconducting conductors 7 become equal, an alternating current flows uniformly in all the high-temperature superconducting conductors 7, and a sufficient critical current for the alternating current is obtained.

In the high temperature superconducting cable of the second invention, the high temperature superconducting multi-core tape 8 is used not only in the conducting layer 3 but also in the magnetic shield conductor layer 5, so that the magnetic shield conductor layer 5 is used. When grounded, the AC magnetic field is shielded by the high temperature superconducting conductor 7 in the magnetic shield conductor layer 5 and is unlikely to leak to the outside.

[0014]

[Embodiment 1] A core for an AC high temperature superconducting cable of the present invention will be described in detail based on an embodiment shown in FIG. In FIG. 1, 2 is a former, 3 is a conducting layer provided on the outer periphery of the former, 4 is an electric insulator arranged outside thereof, 5 is a magnetic shield conductor layer (ground electrode) provided outside thereof, and 11 is It is a shielding layer.

The former 2 is a circular tube in which a refrigerant passage 1 for flowing a cryogenic refrigerant is formed.

The electrical insulator 4 is, for example, a paper tape impregnated with liquid nitrogen, a plastic tape, a semi-synthetic paper obtained by laminating a paper tape and a plastic tape, or the like, which is also a conventional one. It is the same as the electrical insulator.

As shown in FIG. 2 (a), a plurality of thin high-temperature superconducting conductors 7 are stacked in the stabilizing material 6 and the high-temperature superconducting conductors 7 are arranged in a twisted arrangement on the conducting layer 3 for energization. The high temperature superconducting multi-core tape 8 is used. This high temperature superconducting multi-core tape 8 is obtained, for example, as follows. As shown in FIG. 2B, an ultrafine multi-core wire 10 in which a large number of thin high-temperature superconducting conductors 7 are stacked in a silver stabilizing material 5 is prepared, and at the same time, the extra-fine multi-core wire 10 is twisted in a spiral shape and twisted in a spiral shape. Twisted and stretched this extra-fine multi-core wire 1
0 is rolled into a predetermined shape and further sintered.

As the high temperature superconducting conductor 7, bismuth is used.
Those composed of a lead-strontium-calcium-copper-oxygen system or a thallium-barium-calcium-copper-oxygen system high temperature superconductor are suitable. The thickness is preferably about 10 to 50 μm.

The twist pitch of the extra fine multifilamentary wire 10 is preferably 5 to 30 times the outer diameter of the extra fine multifilamentary wire 10 before rolling. If it is less than 5 times, the twist (twist) may be tight and the superconducting characteristics of the high temperature superconducting conductor 7 may be impaired. If it is more than 30 times, the twist amount (twist amount) may be insufficient. The thickness of the high temperature superconducting multi-core tape 8 thus obtained is preferably about 0.2 to 0.4 mm.

In FIG. 1, a large number of the high temperature superconducting multi-core tapes 8 are arranged on the outer periphery of the former 2 in a single layer, and the side faces 9 of the adjacent high temperature superconducting multi-core tapes 8 are butted and wound in a spiral shape. Here, the side faces 9 of the adjacent high temperature superconducting multi-core tapes 8 are abutted against each other by causing a three-phase alternating current to flow through the current-carrying conductor layer 3 so that no gap is formed between the side faces 8 of the same tape 7. This is to prevent the AC magnetic field from leaking inside.

The spiral winding pitch of the high temperature superconducting multi-core tape 8 is 5 to 15 times the diameter of the cylinder (the outer circumference of the former 2 in FIG. 1) formed by spirally winding the high temperature superconducting multi-core tape 8. Suitable.

The high temperature superconducting multi-core tape 8 is used for the magnetic shield conductor layer 5 of FIG. Further, a stainless tape is used for the shielding layer 11 like the conventional one.

In the high temperature superconducting cable of this embodiment, the superconducting multi-core tape 8 forming the conducting layer 3 for energization is provided with the plurality of high temperature superconducting conductors 7 twisted in the stabilizing member 6. Therefore, the high-temperature superconducting conductor 7 is located on the inner peripheral side of the current-carrying conductor layer 3 at some positions and on the outer peripheral side at other positions. Therefore, any of the high-temperature superconducting conductors 7 has substantially the same geometrical arrangement on the outer periphery of the former 2. As a result, the impedance of all the high-temperature superconducting conductors 7 becomes the same, and the alternating current flows uniformly in all the high-temperature superconducting conductors, showing a sufficient critical current for the alternating current.

In the high temperature superconducting cable of this embodiment, the superconducting multicore tape 8 is further wound around the outer periphery of the former 2, so that each high temperature superconducting conductor 7 is 360 degrees in the circumferential direction of the former 2. Rotate. This point also helps to eliminate the difference in geometrical arrangement on the outer circumference of the former 2, and contributes to the effect of showing a sufficient critical current with respect to the alternating current as described above.

Further, in the high temperature superconducting cable of this embodiment, since the magnetic shield conductor layer 5 is also formed by the superconducting multicore tape 8, this magnetic shield conductor layer 5 is also used.
If is grounded, it is possible to highly block the AC magnetic field generated by applying an AC current to the current-carrying conductor layer 3.

[0026]

Other Embodiments In the present invention, the high temperature superconducting multi-core tape 8 is used.
You may wind two or more layers. However, even if two or more layers are wound, the high-temperature superconducting conductor 7 does not move back and forth between the inner and outer layers, so the impedance is different between the inner-layer high-temperature superconducting conductor 7 and the outer-layer high-temperature superconducting conductor 7. Since it becomes difficult for an alternating current to flow in the layer, there is little merit in using two layers. In the present invention, it is not always necessary to use the illustrated high-temperature superconducting multi-core tape 8 for the magnetic shield conductor layer 5, but a high-temperature superconducting tape having a superconducting conductor 7 in the stabilizing material 6 has another structure. May be

[0027]

[Experimental Example] As an experimental example of the present invention, a large number of thin high-temperature superconducting conductors 7 are laminated in the stabilizing material 6 on the outer periphery of a cryogenic refrigerant tube (former) 2 having an outer diameter of 50 mm, and the high-temperature superconducting conductor 7 is Twisted width of about 3mm, thickness of about 200μ
50 sheets of high temperature superconducting multi-core tape 8 of m
Moreover, the side surfaces 8 of the adjacent high temperature superconducting multi-core tapes 7 are butted against each other and wound to form the current-carrying conductor layer 3. The AC critical current of each tape is about 5A on average (effective value)
Met. The alternating frequency at this time was 50 Hz, and the measurement was performed in liquid nitrogen having an absolute temperature of 77K. On the other hand, the same AC critical current in the entire 50 high-temperature superconducting multi-core tapes 8 was about 250A. As a result, a plurality of high-temperature superconducting multi-core tapes 8 are wound around the conducting layer 3 for conduction.
The AC critical current of each of the high-temperature superconducting multi-core tapes 8 in FIG. It was confirmed that the current did not decrease.

[0028]

The high temperature superconducting cable of the present invention uses the high temperature superconducting multi-core tape 8 in which the high temperature superconducting conductor 7 in the stabilizing material 6 is provided in a twisted arrangement.
The impedance of all high-temperature superconducting conductors 7 becomes the same, and the alternating current flows evenly in the high-temperature superconducting conductors 7 of all layers regardless of the inner layer and the outer layer, so that it is sufficiently critical for the alternating current. It becomes a high temperature superconducting cable that has an electric current.

[Brief description of drawings]

FIG. 1A is a cross-sectional view showing an example of the high-temperature superconducting cable of the present invention, and FIG. 1B is an explanatory view of a former and a conductor layer portion for conducting electricity in the cable.

FIG. 2 (a) is an end view showing an example of a high temperature superconducting multi-core tape used in the high temperature superconducting cable of the present invention, and FIG.
Is a manufacturing explanatory view of the same tape.

FIG. 3A is an end view of a conventional AC transmission cable,
(B) is sectional drawing of the core in the cable of (a).

4 is an end view of the tape used in the cable of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refrigerant passage 2 Former 3 Conducting conductor layer 4 Electrical insulator 5 Magnetic shield conductor layer 6 Stabilizing material 7 High temperature superconducting conductor 8 High temperature superconducting multi-core tape 9 Side surface

Claims (2)

[Claims] 1. A high-temperature superconducting cable having a conductor 2 on the outer periphery of a former 2, the conductor layer 3 comprising a plurality of superconducting multicore tapes 8 provided on the outer periphery of the former 2. The superconducting multicore tape 8 is twisted with a plurality of high-temperature superconducting conductors 7. Stabilized material 6
A high-temperature superconducting cable, which is provided inside. 2. The former 2 is provided with an energizing conductor layer 3 composed of a plurality of superconducting multi-core tapes 8, and a magnetic shield conductor layer 5 composed of a plurality of superconducting multi-core tapes 8 is provided on the outer periphery of the former 2. A high-temperature superconducting cable, wherein the superconducting multicore tape 8 is provided in the stabilizing member 6 in a twisted arrangement of a plurality of high-temperature superconducting conductors 7.