JP6012170B2 - Superconducting coil and superconducting transformer - Google Patents

Description

  The present invention is directed to a superconducting induction device such as a superconducting current limiting device and a superconducting transformer, and a superconducting transformer composed of a superconducting coil which is cooled by immersing liquid nitrogen as a refrigerant in the refrigerant, and the superconducting coil. Related to the vessel.

  Recently, with the advent of high-temperature oxide superconductors having a superconducting critical temperature above the liquid nitrogen temperature (boiling point under atmospheric pressure: 77K), the superconducting induction device constructed using this high-temperature superconducting wire is used. The development of superconducting equipment that cools by immersing it in a liquid nitrogen refrigerant and keeps the superconducting wire below the critical temperature during energization, and its cooling system are progressing.

  Next, taking a superconducting transformer as an example, a conventional structure of a superconducting coil using a high-temperature superconducting wire as its coil conductor and a superconducting transformer is shown in FIGS. 4 to 6, and a liquid nitrogen cooling system for cooling superconducting equipment is shown. An example is shown in FIG.

  4 and 5 (a) and 5 (b) are schematic configuration diagrams of a superconducting coil disclosed in Patent Document 1 as a prior art example. In each figure, 1 is an iron core of a transformer, 2 Is a high voltage coil layer disposed opposite to the outer peripheral side of the low voltage coil layer 2, and the low voltage coil layer 2 and the high voltage coil layer 3 surround the leg portion (vertical direction) of the iron core 1 on the inner and outer periphery. As described later, a concentric arrangement is used, and a coolant such as liquid nitrogen is passed between the coil layers to cool to a very low temperature, and the superconducting coil is maintained in a superconducting state below the critical temperature for operation. . In the illustrated example, the low voltage coil layer 2 is divided into one layer, and the high voltage coil layer 3 is divided into two inner and outer coil layers 3a and 3b.

  Here, the superconducting coil according to the prior art has a tape-like high-temperature superconducting wire 5 on the outer peripheral surface side of a cylindrical winding frame 4 made of an insulating material such as FRP as shown in FIGS. 5 (a) and 5 (b). Is wound in a spiral. In this case, the high-temperature superconducting wire (high-temperature oxide superconductor) 5 currently being developed is in the form of a tape having a thickness of about 0.1 mm and a width of about 5 mm. A spiral groove 4a is machined on the outer peripheral surface of the winding frame 4 in accordance with the dimensions, and the tape-like superconducting wire 5 is wound along the groove 4a so as to be embedded in one or more strips. Turned and assembled. In addition, in order to efficiently remove heat generated by energization of the superconducting wire 5, in the illustrated structure, liquid nitrogen is dispersed in the axial direction so as to cross the spiral groove 4 a on the outer peripheral surface of the winding frame 4. A cooling duct 4b that flows is formed.

  Further, in the superconducting transformer in which the low-voltage coil layer 2 and the high-voltage coil layer 3 are constituted by the superconducting coils, as shown in FIG. 6, the disk-shaped coil support member 6 in which the winding frames 4 of the respective coil layers are arranged on the upper and lower sides. The upper and lower coil support members 6 are fastened and fixedly supported by stud bolts (not shown). In this assembled state, an insulation distance d is set between the low voltage coil layer 2 and the high voltage coil layer 3, and a predetermined dielectric strength based on the transformer specifications (% impedance, etc.) (however, it is immersed in liquid nitrogen). Is ensured). In addition, in the state which this coil assembly was accommodated in the refrigerant | coolant container and immersed in liquid nitrogen, the disk surface of the coil support member 6 is suitably set so that the said disk shaped coil support member 6 may not inhibit the convection of a refrigerant | coolant. Refrigerant holes (not shown) are dispersed and perforated so as to ensure a convective flow of liquid nitrogen flowing along the coil layers.

  Next, FIG. 7 shows an example of a liquid nitrogen cooling system that cools superconducting equipment such as a superconducting coil and a superconducting transformer using liquid nitrogen as a refrigerant (see, for example, Non-Patent Document 1). This cooling system is divided into a refrigerant container (cryostat) 8 containing a superconducting induction device 7 (for example, a superconducting transformer) and a refrigerator unit 10 equipped with a cryogenic refrigerator 9, and then a liquid feed pump 11. Liquid nitrogen 13 accommodated in the refrigerator unit 10 is circulated between the refrigerant container 8 via the circulation line 12 and the heat load caused by energization is operated by the liquid nitrogen 13 when the superconducting induction device 7 is operated. I try to remove heat. In the refrigerator unit 10, the liquid nitrogen 13 is cooled to subcooled supercooled liquid nitrogen (for example, 65 K) by the cryogenic refrigerator 9, and then sent to the cryogenic container 8. In the figure, 7a is a current lead (bushing) connected to the coil of the superconducting device and drawn out of the container, and 13a is nitrogen gas filling the gas space on the liquid surface of the liquid nitrogen 13.

  By the way, in the normal operation state of the superconducting equipment used by being immersed in the liquid nitrogen in the subcooled state as described above, the superconducting coil is maintained in the superconducting state below the critical temperature, so the superconducting wire does not generate Joule heat and is in liquid nitrogen. Keep the same temperature as the temperature. However, if an excessive current exceeding the expected value flows in the coil of the superconducting device due to an electrical system accident (short circuit), etc., the critical current will be exceeded and the transition from the superconducting state to the normal conducting state will cause resistance to the high-temperature superconducting wire, Due to the Joule heat generation, the temperature of the superconducting wire rapidly increases.

  If it will be in this state, the liquid nitrogen which received the heat transfer from the superconducting wire which generated heat at a high temperature will boil beyond the boiling point (77K), and bubbles will be generated in the liquid nitrogen. In this case, liquid nitrogen is originally a good insulating medium, but since its dielectric strength is greatly reduced by vaporization, a large amount of air bubbles stays in the refrigerant container (ground potential) containing the superconducting device. When this occurs, the withstand voltage of superconducting coils, current leads, etc. may decrease, causing dielectric breakdown.

  Therefore, as a measure to quickly extinguish bubbles generated by the boiling of liquid nitrogen, which is a refrigerant during operation of superconducting equipment, and maintain a predetermined insulation performance, the bubbles are actively collected and discharged out of the container. Alternatively, there is known a superconducting device provided with bubble extinguishing means such as collecting in a container (for example, see Patent Document 2).

Japanese Patent Laid-Open No. 2001-244108 (FIGS. 3, 5, and 6) JP 2007-273740 A

Shigeru Yoshida and one other, "Cooling System Using Atmospheric Pressure Supercooled Liquid Nitrogen", Fig. 3, [online], Taiyo-Nikko Technical Report No. 23 (2004), [Searched on November 1, 2011] , Internet <URL: http://www.tn-sanso-giho.com/pdf/23/16.pdf>

  By the way, even if the subcooled liquid nitrogen is used as the coolant for cooling the superconducting coil as described above, and the bubble extinguishing means as disclosed in the above-mentioned Patent Document 2 is further provided, an accident in the power system, etc. When the high-temperature superconducting wire of the superconducting coil changes from superconducting to normal conducting due to the overcurrent caused by the current, bubbles are generated in the liquid nitrogen due to heat transfer from the superconducting coil that has risen to a high temperature due to Joule heating. Inevitably, the above-mentioned bubble extinguishing means is also practically limited in its capability and is not a fundamental solution for preventing a decrease in the dielectric strength of superconducting equipment due to the generation of bubbles.

  In addition, in the assembly structure in which the upper ends of the winding frames 4 of the low-voltage coil layer 2 and the high-voltage coil layer 3 are supported by a disk-shaped coil support member 6 disposed on the upper side, as in the superconducting transformer shown in FIG. When bubbles generated by boiling accompanying the heat generation of the superconducting wire 5 float and move while diffusing in the liquid nitrogen and stay on the lower surface side of the coil support member 6, the low voltage coil layer 2 and the high voltage coil as described above Even if a predetermined insulation distance d is set between the layer 3 and the layer 3, there is a concern that the withstand voltage between the layers may be reduced to cause dielectric breakdown.

  Regarding the model in which the inventors simulated the superconducting coil shown in FIG. 5 and immersed in liquid nitrogen in a subcooled state, bubbles generated in liquid nitrogen when an overcurrent simulating a short-circuit current was passed through the superconducting coil. According to the observation of this behavior with a high-speed camera, boiling occurs on the surface of the tape-like high-temperature superconducting wire in contact with liquid nitrogen immediately after the start of overcurrent energization, and bubbles are continuously generated and moved upward. Further, it was confirmed that a large number of bubbles generated on the surface of the high-temperature superconducting wire were generated around the refrigerant duct groove 4b formed in the winding frame 4 of FIG. This is presumably because the heat flux at the heat transfer interface increases because liquid nitrogen is in direct contact with both the front and back surfaces of the tape-like high-temperature superconducting wire.

  Therefore, the present invention is based on the observation results of the bubble behavior described above, and the superconducting coil and the superconducting transformer cooled by being immersed in liquid nitrogen are changed from the superconducting wire to the normal conducting state due to excessive current conduction. It is an object of the present invention to provide a superconducting coil improved so that the generation of liquid nitrogen bubbles can be suppressed as much as possible to maintain a predetermined insulating characteristic even when the transition is made, and a superconducting transformer configured using the superconducting coil.

In order to achieve the above object, according to the present invention, a tape-shaped high-temperature superconducting wire is wound around the outer peripheral surface of a cylindrical winding frame, and is cooled by being immersed in the refrigerant using liquid nitrogen as a refrigerant. In the superconducting coil
A spiral groove corresponding to the tape width of the high-temperature superconducting wire is formed on the outer peripheral surface of the cylindrical winding frame, and the tape surface of the superconducting wire is wound along the spiral groove on the inner diameter side of the coil. The outer diameter side of the coil is covered with insulating tape so that the tape surface of the superconducting wire is covered from the outside,
The cooling duct through which the refrigerant flows is not formed on the peripheral surface of the winding frame, and the tape surface is isolated so that the refrigerant does not directly touch the front, back both tape surfaces and side surfaces of the superconducting wire . Specifically, it can be configured in the following manner.
(1) The insulating tape is embedded in the spiral groove (claim 2).
(2) The insulating tape is obtained by applying a thermosetting treatment after covering the tape surface of the superconducting wire from the outside with a prepreg tape in which a glass cloth is impregnated with a semi-cured epoxy resin. ).

On the other hand, a disk in which a low-voltage coil layer and a high-voltage coil layer configured using the superconducting coil are concentrically arranged on the outer side of the iron core leg with an interval between the inner and outer circumferences, and the winding frames of the respective coil layers are arranged vertically. In the superconducting transformer supported between the coil-shaped coil support members and placed in the refrigerant,
Between the low voltage coil layer on the inner peripheral side and the high voltage coil layer on the outer peripheral side, a barrier layer for preventing bubble diffusion that becomes a cylindrical partition wall of the insulating material is relatively disposed around the low voltage coil layer as compared with the high voltage coil layer. A predetermined insulation distance corresponding to the dielectric strength between the high voltage coil and the low voltage coil may be set between the barrier layer and the high voltage coil layer .

In the superconducting transformer, the winding frames of the low-voltage coil layer and the high-voltage coil layer are arranged so that the length from the upper end of the winding area of the superconducting wire is longer than the length from the lower end of the winding area. It is good to have the extension part extended in (claim 5).
Moreover, it is good for the axial direction length of the said extension part to be set to at least 60 mm or more (Claim 6).

According to the superconducting coil and the superconducting transformer configured as described above, it is possible to suppress the generation of bubbles of liquid nitrogen as much as possible and maintain a predetermined insulating performance. That is,
(1) While superposing the tape surface of the superconducting wire on the inner diameter side of the coil on the peripheral surface of the winding frame, the outer diameter side of the coil is covered with an insulating tape so as to cover the tape surface of the superconducting wire from the outside. By isolating the tape surface so that it does not come into direct contact with the refrigerant, the heat transfer area where the superconducting wire and liquid nitrogen are in direct contact with each other is minimized, and the insulating tape (low thermal conductivity) coated on the outer peripheral tape surface of the superconducting wire is transferred. It becomes a thermal resistor, and the heat transfer between liquid nitrogen becomes low. Therefore, even when the superconducting wire transitions from the superconducting state to the normal conducting state due to excessive current flow, the generation of liquid nitrogen bubbles can be suppressed as much as possible to prevent deterioration of the insulating characteristics of the superconducting coil.
(2) Here, the superconducting wire is wound so as to be embedded in the groove along the spiral groove formed on the peripheral surface of the coil, and then the outer peripheral tape surface is covered with an insulating tape. Further, the contact area between the superconducting wire and liquid nitrogen is further reduced to more effectively suppress the generation of bubbles, and the dielectric strength between coil turns is also improved.
(3) In addition, a binding tape having a high tensile strength, such as a glass cloth tape having a high tensile strength, impregnated with a semi-cured epoxy resin, etc. is used as an insulating tape to cover the tape surface of the high-temperature superconducting wire. By doing so, the superconducting coil can be supported in the radial direction against the electromagnetic force acting on the superconducting wire when energized with an overcurrent, and subcooled liquid nitrogen (for example, 66K) is used as a coolant for cooling the superconducting coil. By using it, the critical current of the superconducting wire is increased as compared with saturated liquid nitrogen (77K), and the generation of bubbles is reduced.

On the other hand, in the superconducting transformer constituted by the superconducting coil, a barrier layer for preventing bubble diffusion, which becomes a cylindrical partition wall of insulating material between the low voltage coil layer and the high voltage coil layer, approaches the peripheral surface of the low voltage coil layer. According to the configuration of the present invention, a predetermined insulation distance corresponding to the dielectric strength between the high voltage coil / low voltage coil is set between the barrier layer and the high voltage coil layer.
Even if bubbles are generated in the liquid nitrogen due to Joule heating of the high-temperature superconducting wire that has transitioned to the normal conducting state due to the overcurrent, the bubbles generated on the peripheral surface of the low-pressure coil layer are blocked by the barrier layer. The bubbles do not diffuse toward the coil layer, and the bubbles are confined in the gap between the barrier layer and the outer peripheral surface of the low-voltage coil layer, and just float and move upward. In addition, since a predetermined insulation distance is set in advance between the barrier layer and the high voltage coil layer, the insulation characteristics determined by the specifications of the superconducting transformer are ensured to ensure the dielectric strength between the high voltage coil layer and the low voltage coil layer. Can be held.

In addition, in each layer winding frame of the low-voltage coil layer and the high-voltage coil layer in the superconducting transformer, an extension portion extending further upward from the upper end of the winding area of the superconducting wire is formed, and the axial length of the extension portion is By setting the thickness to at least 60 mm or more, even if bubbles are generated on the surface of the superconducting wire wound around the winding frame of each coil layer due to heat generation due to overcurrent conduction, the bubbles are formed on the peripheral surface of the extension portion. In the course of moving upward along the line, it is cooled by the surrounding liquid nitrogen and disappears before reaching the disk-shaped coil support member disposed above, so that the influence on the insulation characteristics can be avoided.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic block diagram of the superconducting coil concerning 1st Example of this invention, (a) is an external appearance perspective view of the whole coil, (b) is an expanded sectional view of a part of coil in (a). It is an expanded sectional view of a part of coil of a superconducting coil concerning the 2nd example of the present invention. It is a longitudinal cross-sectional view showing the assembly structure of the coil layer of the superconducting transformer concerning the Example of this invention. It is a schematic arrangement drawing of a superconducting coil for a superconducting transformer. It is a structure and arrangement | positioning figure of the prior art example of the high voltage | pressure coil layer in FIG. 4, and a low voltage | pressure coil layer, Comprising: (a) is a longitudinal cross-sectional view, (b) is a cross-sectional enlarged view of (a). It is a longitudinal cross-sectional view showing the assembly structure of the conventional high voltage coil layer and low voltage coil layer of the superconducting transformer corresponding to FIG. It is a system flow figure of a liquid nitrogen cooling system applied to a superconducting coil and a superconducting transformer.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a superconducting coil and a superconducting transformer according to the present invention will be described below based on examples shown in FIGS. In the drawings of the respective embodiments, the same members corresponding to those in FIGS. 5 and 6 are denoted by the same reference numerals and description thereof is omitted.

  First, FIGS. 1A and 1B show the configuration of a superconducting coil according to the first embodiment of the present invention. In this embodiment, a tape-shaped high-temperature superconducting wire 5 wound on the outer peripheral surface of a cylindrical winding frame 4 made of an insulating material such as FRP is wound on the tape inner surface of the coil. The coil 4 is wrapped directly on the peripheral surface of the frame 4 and covered with an insulating tape 14 so as to cover the tape surface of the superconducting wire 5 from the outside on the outer diameter side of the coil. It is isolated so that it does not touch the back tape surface directly. This superconducting coil is immersed in a liquid nitrogen refrigerant in a vertical arrangement, and O in the figure represents the axial center of the cylindrical winding frame 4. In the illustrated example, the superconducting wire 5 is wound around the winding frame 4, but a plurality of wires may be wound in layers.

  Here, the insulating tape 14 is, for example, a prepreg glass binding tape in which a glass cloth tape with high tensile strength is impregnated with a semi-cured epoxy resin and wound around the tape surface of the superconducting wire 5. It is cured by applying a thermosetting treatment.

  According to the superconducting coil having the above-described configuration, it is possible to maintain the predetermined insulation performance by suppressing the generation of liquid nitrogen bubbles as much as possible during energization. That is, when the superconducting coil is immersed in liquid nitrogen, the front and back tape surfaces of the superconducting wire 5 wound around the peripheral surface of the winding frame 4 are isolated so as not to come into direct contact with liquid nitrogen. As a result, the heat transfer area where the superconducting wire 5 and liquid nitrogen are in direct contact with each other is minimized, and the low thermal conductivity insulating tape 14 covered on the outer peripheral tape surface of the superconducting wire 5 serves as a heat transfer resistance between the superconducting wire 5 and liquid nitrogen. Therefore, even when the superconducting wire transitions from the superconducting state to the normal conducting state due to excessive current conduction and the superconducting wire 5 generates Joule heat, the generation of bubbles of liquid nitrogen can be suppressed as much as possible.

  Moreover, about the insulating tape 14, by using the bind tape having high tensile strength as described above, the superconducting coil is supported in the radial direction against the electromagnetic force acting on the superconducting wire 5 when energized with overcurrent. Can do. Furthermore, the use of subcooled liquid nitrogen (for example, 66K) as a coolant for immersing and cooling the superconducting coil increases the critical current compared to the use of saturated liquid nitrogen (77K), and also generates bubbles. Decrease.

  Note that the above-described bubble generation suppression effect is also verified in the “Bubble Behavior Observation Test” conducted by the inventors on a superconducting coil model. That is, in this observation test, as the test model of the superconducting coil, the conventional coil (without the insulating tape 15) shown in FIG. 5 and the coil of the embodiment to which the present invention is applied are prepared. When an excessive current simulating a short-circuit current was passed through a conductor and the occurrence of bubbles generated in liquid nitrogen was observed, the average diameter and number of bubbles generated were significantly reduced in the case of the coil of the example. It has been demonstrated that the amount of bubbles generated during the overcurrent energization time can be suppressed to about 1/5 or less in volume ratio.

  Next, FIG. 2 shows a configuration of a second embodiment according to claim 2 of the present invention. In this embodiment, a spiral groove 4a having a groove width corresponding to the tape width of the high-temperature superconducting wire 5 is formed in advance on the outer peripheral surface of the cylindrical winding frame 4, and along this spiral groove 4a. After winding so that the superconducting wire 5 is embedded in the groove, the insulating tape 14 is wound from the outer peripheral side so as to cover the superconducting wire 5 as in the first embodiment.

  As a result, the generation of bubbles is suppressed as in the first embodiment, and the superconducting wire 5 embedded in the groove of the spiral groove 4a further reduces the contact area with the liquid nitrogen and has the effect of suppressing the generation of bubbles. In addition to the increase, the creepage distance between the coil turns is increased and the dielectric strength is further improved.

  Next, an embodiment of a superconducting transformer corresponding to claims 5 and 6 of the present invention constructed by adopting the above-described superconducting coil will be described with reference to FIG.

  The superconducting transformer of this embodiment has an assembly structure basically similar to that of the conventional superconducting transformer shown in FIG. 6, and the configuration of the superconducting coil described in the second embodiment (see FIG. 2). A disk-shaped coil support member 6 in which the low-voltage coil layer 2 and the high-voltage coil layer 3 are concentrically arranged on the outer side of the iron core leg with an interval between the inner and outer circumferences, and the winding frames 4 of the respective coil layers are arranged on the upper and lower sides. The coil assembly is immersed in a liquid nitrogen refrigerant in the illustrated vertical position.

Here, between the low voltage coil layer 2 and the high voltage coil layer 3 according to the present invention, a bubble diffusion preventing barrier layer 15 which becomes a cylindrical partition wall of an insulating material is provided between the peripheral surface of the low voltage coil layer 2 and 5 mm. An insulating distance d2 corresponding to the required dielectric strength between the high voltage coil and the low voltage coil is set between the barrier layer 15 and the high voltage coil layer 3 while being arranged close to the narrow gap d1.

  With this configuration, even if bubbles are generated in the liquid nitrogen due to Joule heat generation of the high-temperature superconducting wire 5 that has transitioned to the normal conducting state due to overcurrent, the bubbles generated on the peripheral surface of the low-pressure coil layer 2 are It is blocked by the layer 15 and does not diffuse toward the high-voltage coil layer 3, and is confined in a narrow gap between the barrier layer 15 and the outer peripheral surface of the low-voltage coil layer 2 and floats and moves upward as it is. Further, since no bubbles are generated on the inner peripheral surface side of the cylindrical winding frame 4 of the high voltage coil layer 3, the space between the barrier layer 15 and the high voltage coil layer 3 is filled with liquid nitrogen without bubbles. Not affected by air bubbles. In addition, since a predetermined insulation distance d2 is set in advance between the barrier layer 15 and the high voltage coil layer 3a arranged on the inner peripheral side of the high voltage coil layer 3 (two-layer divided structure), the low voltage coil layer 2 and the high voltage coil layer 3a. A predetermined dielectric strength can be secured between the coil layer 3 and a predetermined insulation characteristic determined by the specifications of the superconducting transformer can be maintained.

  In this case, bubbles generated on the outer peripheral surface side of the low-voltage coil layer 2 stay in a gap between the barrier layer 15 and the potential of the barrier layer 15 is substantially the same as the potential of the low-voltage coil 2 through the bubbles. Even when the potential is reached, there is no problem because the predetermined insulation distance d2 is set between the barrier layer 15 and the high-voltage coil layer 3 as described above, and the coil layers 3a and 3b of the high-voltage coil layer 3 have no problem. Even if bubbles are generated on the outer peripheral surface, there is hardly any influence on the low voltage coil layer 2 facing the inner peripheral side of the high voltage coil layer 3 with a gap d2.

Further, in the illustrated embodiment, on the upper end side of the winding frame 4 of the low voltage coil layer 2 and the high voltage coil layer 3, a length extending further upward from the upper end of the winding area of the superconducting wire 5 wound around the winding frame 4 is shown. After the extension portion having the length L is formed, the axial length L of the extension portion is set to at least 60 mm. As a result, even if bubbles are generated on the surface of the superconducting wire 5 wound around the winding frame 4 of each coil layer due to the overcurrent, the bubbles move upward along the peripheral surface of the extension. In the course of the process, the air is cooled with the surrounding liquid nitrogen (subcooled liquid nitrogen), and the bubbles almost disappear before reaching the disk-shaped coil support member 6 disposed on the upper side. In addition, the behavior until the bubbles disappear is also confirmed in the above-mentioned “Behavior Behavior Observation Test” conducted by the inventors, and when liquid nitrogen is used as the refrigerant, the bubbles are generated until the disappearance. It has been experimentally verified that the distance to this is about 60 mm.

Therefore, by forming an extension part with an axial length of 60 mm or more on the upper end side of the winding frame 4 of each coil layer as described above, the coil layer has an outer peripheral surface side with energization of overcurrent. The bubbles that are generated and floated upward pass through the refrigerant holes for refrigerant convection opened on the disk surface of the disk-shaped coil support frame 6 arranged on the upper end side of the winding frame 4 as they are, and are arranged above the current leads 7a. (See Fig. 7) and the like can be prevented from occurring troubles that impair the insulation, and bubbles are generated in the liquid nitrogen of the refrigerant due to overcurrent conduction during operation of the superconducting transformer. However, the electrical insulation performance can be maintained.

DESCRIPTION OF SYMBOLS 1 Iron core 2 Low voltage coil layer 3 High voltage coil layer 4 Winding frame 4a Spiral groove 5 High temperature superconducting wire 6 Coil support member 8 Refrigerant container 10 Liquid nitrogen cooling unit 13 Liquid nitrogen 14 Insulating tape 15 Barrier layer d2 Barrier layer / high voltage coil layer Insulation distance L Axial length of reel extension

Claims (6)

In a superconducting coil in which a tape-shaped high-temperature superconducting wire is wound around the outer peripheral surface of a cylindrical winding frame, and is cooled by being immersed in the refrigerant as liquid nitrogen,
A spiral groove corresponding to the tape width of the high-temperature superconducting wire is formed on the outer peripheral surface of the cylindrical winding frame, and the tape surface of the superconducting wire is wound along the spiral groove on the inner diameter side of the coil. The outer diameter side of the coil is covered with insulating tape so that the tape surface of the superconducting wire is covered from the outside,
The cooling duct through which the refrigerant flows is not formed on the peripheral surface of the winding frame, and the tape surface is isolated so that the refrigerant does not directly touch the front, back both tape surfaces and side surfaces of the superconducting wire . A superconducting coil characterized by that.   2. The superconducting coil according to claim 1, wherein the insulating tape is embedded in the spiral groove.   The superconducting coil according to claim 1 or 2, wherein the insulating tape is subjected to a thermosetting treatment after covering the tape surface of the superconducting wire from the outside with a prepreg tape in which a glass cloth is impregnated with a semi-cured epoxy resin. A superconducting coil characterized by being made. A low voltage coil layer and a high voltage coil layer configured using the superconducting coil according to any one of claims 1 to 3 are concentrically arranged on the outer side of the iron core leg with an interval between the inner and outer circumferences. In the superconducting transformer, which is supported between the disk-shaped coil support members arranged on the top and bottom and immersed in the refrigerant,
Between the low voltage coil layer on the inner peripheral side and the high voltage coil layer on the outer peripheral side, a barrier layer for preventing bubble diffusion that becomes a cylindrical partition wall of the insulating material is relatively disposed around the low voltage coil layer as compared with the high voltage coil layer. A superconducting transformer characterized in that a predetermined insulation distance corresponding to a dielectric strength between a high voltage coil and a low voltage coil is set between the barrier layer and the high voltage coil layer.   5. The superconducting transformer according to claim 4, wherein the winding frame of the low voltage coil layer and the high voltage coil layer has a length from the upper end of the winding region of the superconducting wire longer than a length from the lower end of the winding region. And a superconducting transformer having an extension portion extending upward.   6. The superconducting transformer according to claim 5, wherein an axial length of the extension is set to at least 60 mm or more.

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