JPH0731053A - Member for magnetic flux jump type current limiter and production thereof - Google Patents

Abstract

PURPOSE:To enhance the shielding efficiency by employing a single crystal as a hollow superconducting shield member and varying the quantity of substance composing the shield member thereby varying the field shielding characteristics. CONSTITUTION:A hollow superconducting shield member 2 is composed of a REBa2Cu3O7-x. single crystal based single crystal finely dispersed with RE2 BaCuO5 wherein the field shielding characteristics are varied by varying the quantity of RE2BaCu5 in the REBa2Cu3O7-x represents one or more kind of element selected from a group of Nd, Sm, Eu, Gd, Dy, Y, Ho, Er, Tm, Yb, Lu. This composition enhances the shielding efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic flux jump type superconducting current limiting device using an oxide high temperature superconducting material and a manufacturing method thereof.

[0002]

2. Description of the Related Art The application of superconductors to electric power equipment has been studied in conventional metal-based superconducting materials before the discovery of oxide superconductors. In particular, as an effective application field of superconducting devices for electric power, development of an accident time limiter (current limiting device) that suppresses short circuit current and reduces duty of a circuit breaker when an accident occurs is desired.

Conventionally, there have been proposed current limiting element type, rectifying type and reactor type current limiting devices using a metal-based superconducting material. However, since the metal-based superconductor has a low electric resistance value in the normal conducting state and earns the normal conducting resistance, the metal superconductor requires a certain length or more, and it is inevitable to be a large-scale device.
Further, since it is necessary to use the liquid helium at a high operating cost, there is a problem that the device becomes large and expensive due to heat insulation or the like, and it has not been put to practical use. .

Therefore, in recent years, a current limiter using an oxide superconductor, which has a high electric resistance in a normal conducting state and can maintain a superconducting state with liquid nitrogen at a low cost, has been studied. In addition to this, recently, an inductive / resistive combined current limiter (Japanese Patent Laid-Open No. 2-105402: Helmut Dersch) is proposed, in which an iron core, an induction coil, and a cylindrical jacket formed of an oxide superconductor are combined. Has been done. Since this method has a relatively simple configuration, there is a possibility that the entire system can be downsized. In the combined induction / resistance type current limiter, the basic principle is to shield the induced magnetic field generated during energization by the Meissner effect (complete diamagnetism).

A simple operating principle of the combined induction / resistance type current limiter will be described with reference to the drawings. As shown in FIG. 1, the constituent elements are composed of three parts: a current-carrying induction coil 1, a high-permeability iron core yoke 3, and an oxide superconducting jacket shield 2 manufactured by a cylindrical reaction sintering method. A current flows through this energization induction coil, and at a normal current value, the cylindrical jacket is in a superconducting state, and the magnetic field generated by the energization coil is completely shielded from the iron core by the Meissner effect. Therefore, the inductance of the entire system is low. However, if there is a short circuit and an excessive current flows through the energizing coil, the shielding properties of the jacket will be broken and the system will behave like a normal choke coil, limiting the short circuit. The above is the simple operating principle of the combined induction / resistance type current limiter. However, in this case, the operating principle is magnetic shielding by the Meissner effect, and in the type II superconductor including the oxide superconductor, when the Meissner effect is broken, the quantized magnetic flux enters the superconductor, and the superconducting state and normal conduction The state is a mixed state in which the states are mixed.
If the Meissner state is broken from this, the magnetic field will only enter the superconductor, and a sufficient current limiting effect cannot be expected. Furthermore, the oxide superconducting jacket produced by the reaction sintering method is a polycrystalline body. In the oxide superconducting material, the crystal grain boundaries act as weak bonds, as is well known, and it is easy for the magnetic flux to enter and exit at the crystal grain boundaries, and there is not a very high shielding property. From this fact, it seems that it is difficult to put the combined induction / resistance current limiter using the sintered polycrystalline oxide superconductor into practical use.

[0006] Independently of this, a current limiting device has been proposed which applies the superconducting magnetic flux switching effect by applying the principle peculiar to the second type superconductor [Electrotechnical Laboratory: Ohnishi et al., 4th, 1990].
3rd Spring Low Temperature Engineering / Superconductivity Society Proceedings B1-14 (19
90), Research Institute of Electrical Engineers: Onishi et al., Proceedings 1993 (1991) of the 1st Annual Meeting of the Institute of Electrical Engineers of Japan,]. The operating principle is that the magnetic flux generated in the superconductor jumps to the high-permeability iron core yoke due to the increase in the magnetic field generated by the excessive current flowing in the superconductor during a short circuit. . Based on this principle, it has already been reported in the above references that metallic superconducting materials are used to operate at liquid helium temperatures. This is due to the excellent shielding properties of metal-based superconducting materials and the introduction of pinning sites that allow magnetic flux to jump in a certain magnetic field. Here, the current limiter applying the superconducting magnetic flux switching effect will be referred to as a flux jump type current limiter because of its characteristics. The magnetic flux jump type fault current limiter using metal superconductivity that has already been developed has a relatively large size as a system because it uses liquid helium, and its economic merit is small at this stage.

When an oxide superconductor is applied to a magnetic flux jump type current limiter, liquid nitrogen, which is inexpensive and has a relatively simple cold insulation system, can be used, so that it can be miniaturized and put into practical use in an economical sense. There is a great possibility. However, the shield property of the oxide superconductor at the liquid nitrogen temperature depends largely on the material manufacturing method. The superconducting material produced by the usual sintering method is a polycrystalline body, and contains a grain boundary which is a weak bond that obstructs the superconducting shielding current flowing through the entire superconductor. Therefore, it is known that the critical current density between superconducting grains is as low as several tens A / cm ² under a magnetic field of 77K and 1T. This is remarkably smaller than the critical current density value (10 ⁴ to 10 ⁶ A / cm ² ) required for practical use.
From the results examined so far, polycrystalline bodies such as sintered bodies can only shield an external magnetic field of several tens to several hundred Gauss ("IEEE Transactions on magnetics" Vol.
25, No. 2, March 1989, p.2506-2510). It has been considered impossible to use an oxide superconductor in a strong magnetic field shield used in a current limiter because the shielding current flowing through the entire shield body is small. In addition, it is necessary for the magnetic flux in the superconductor to jump in a magnetic field above a certain level,
It must control the critical current density value by controlling the pinning site in the superconductor. Such control has not been possible with a superconducting material using a conventional sintering method.

As described above, in order to utilize the oxide superconductor in the magnetic flux jump type current limiter, a material having excellent shielding property must be used especially for high power and medium power applications. Therefore, a flux jump type current limiter using an oxide superconductor has not been realized yet.

[0009]

Therefore, the present inventors have
Recognizing that it is important to develop a cylindrical superconducting member with high shielding properties at liquid nitrogen temperature in order to incorporate and operate an oxide superconductor in a flux jump type fault current limiter, We have studied earnestly how to make it possible to control the shield value that causes the magnetic flux jump by allowing a sufficient superconducting shielding current to flow through the entire shield body and controlling the critical current value, and to implement it easily and inexpensively.

From the above, it has a shield characteristic of 0.3 T or more at the liquid nitrogen temperature, the critical current density value can be controlled so that the magnetic flux jump value can be controlled, and it can be incorporated in the magnetic flux jump type current limiter. An object of the present invention is to provide an oxide superconducting member having a cylindrical shape, and further, a shield member having a brim shape for improving shield efficiency.

[0011]

The inventors of the present invention have earnestly promoted research in order to develop an oxide superconducting material excellent in critical current density characteristics and shield characteristics. Especially YB
By producing an a ₂ Cu ₃ O _7-x- based oxide superconducting material by a melting method, we have succeeded in developing a material having a critical current density that is two orders of magnitude higher than that of a conventional sintering method. Based on the technology cultivated in the material development process, we discovered that the above problems can be solved by producing a precursor with a cylindrical one sided lid and growing crystals from the side with the lid. Then, the present invention has been completed.

That is, as a member for a magnetic flux jump type superconducting fault current limiter, the superconducting member is a REBa ₂ Cu ₃ O _7-x system (R
E: a rare earth element including Y and a combination thereof) and RE ₂ BaCuO ₅ are composed of a finely dispersed superconducting material, and in order to improve the magnetic field shield current limiting property, the hollow superconducting material portion is composed of a single crystal grain, and REBa ₂ Cu ₃
It is characterized in that the magnetic field shield characteristics are changed by changing the amount of RE ₂ BaCuO ₅ in O _7-x . Previously from our obtained experimental findings, REBa ₂ Cu ₃ amount of O fine uniform dispersion in _7-x RE ₂ BaO ₅ can be controlled by changing the feed composition, RE ₂ BaCu
It was found that the critical current degree can be controlled by changing the amount of O ₅ . Specifically, REBa ₂ Cu ₃ O
_{When the} charge composition was changed so that the amount of RE ₂ BaCuO ₅ in _7-x was 0% to 40%, the critical current density was 1
It varies linearly from ten thousand A / cm ² to 30,000 A / cm ^2. According to the simplest critical state model, the maximum magnetic field shield property is proportional to the critical current density. Therefore, REBa ₂ Cu ₃ O
_The shield characteristics can be controlled by changing the amount of RE ₂ BaCuO ₅ in _7-x .

Further, as a method of manufacturing a flux jump type fault current limiter member, raw material powder of REBa ₂ Cu ₃ O _7-x superconducting material is mixed and molded into a cylindrical shape with one end bored, and then the unopened upper surface is semi-melted. In the state, after growing by aligning the crystal orientation by the seeding method using the RE-based seed crystal in which the rare earth is substituted, the upper surface including the crystal growth start portion is perforated to form a hollow cylindrical single crystal granular shield. It is characterized by producing a member.

Further, in the magnetic flux jump type superconducting fault current limiter, a collar-like shield member shape is added to both ends of the hollow shield member by processing or joining after molding to reduce loss due to a leakage magnetic field. To do.

If an oxide superconductor cylindrical member having a high critical current density and a small number of crystal grain boundaries can be produced so that a high shielding property can be obtained at the above-mentioned liquid nitrogen temperature, it can be operated as a current limiting device. The required shield characteristics are obtained. In addition, since the central portion has already been hollowed during crystal growth, there is no concern that cracks or the like will be introduced by the later punching. Therefore, higher shield characteristics can be obtained.

[0016]

In the present invention, as a magnetic flux jump type superconducting fault current limiter member, a single granular REBa ₂ Cu ₃ O _7-x (123) in which REBa ₂ CuO ₅ (211 phase) is finely dispersed.
Phase) is used. Here, the term “single grain” means that since the present method for producing a member is basically a peritectic reaction, even if it is in the form of a single crystal as a whole, it contains a fine 211 phase that remains after the reaction, Expressed as one crystal grain. The 123 phase has a critical temperature of 90 K or higher, and is in a superconducting state at a liquid nitrogen temperature. The 123 phase, which is a superconducting phase, is finely dispersed in the 211 phase, which is a non-superconducting phase. Has been obtained. Such materials can be prepared by the melting method, for example, QMG (Qench and Melt G).
It can be manufactured by using the “rowth) method and the improved QMG method. (QMG method: Japanese Patent Application No. 63-1374
64, Japanese Patent Application No. 63-261607, Improved QMG method: Japanese Patent Application No. 4-55203)

The basic composition used here is RE ₂ O ₃ , C.
u oxide and Ba oxide have metal element ratios (RE: B
a: Cu) in atomic percent (10:60:30),
It is assumed that the composition is in the region surrounded by the points (10:20:70) and (50:20:30). In the above mixture,
0.001 wt% to 1.0 wt% of Pt or Rh powder or Pt or Rh compound is added and kneaded. Sufficiently kneaded mixed powder is pressure molded with a cylindrical mold,
After hydrostatic pressing, a precursor is prepared by punching the center part from one side to the other side with a drilling machine etc. There is also a method that makes it possible to omit the boring step. It pressure-molds with the metal mold | die 4 as shown in FIG. 2, and it hydrostatically press-processes, or produces the precursor of an oxide superconductor. By doing so, the boring step can be omitted.
Similarly, in the mold 5 as shown in FIG. 3, the mixing and kneading powder is introduced into the tube-shaped soft pipe 6, a cylindrical rod is inserted in the central portion, and hydrostatic pressing is performed. By such a method, an oxide superconducting precursor having a closed cylindrical shape on one side is produced.

Next, these precursors are placed in a furnace with the opening facing down, and the partial melting temperature (about 10 when the rare earth element is Y) is set.
It is heated to about 1100 ° C, which is higher than 00 ° C. After heating, cool the furnace temperature to 900 ° C at a cooling rate of 5 ° C / h,
At that time, seed crystals in which rare earth sites were substituted at 1030 ° C. (Japanese Patent Application No. 2-402204, Japanese Patent Application No. 2-299025)
Is placed on the upper part of the precursor, and crystal is grown so that the entire precursor becomes a single crystal grain.

By the method as described above, it is possible to manufacture an oxide superconducting cylindrical member having a uniform crystal orientation and a small number of crystal grain boundaries. In order to use this as a member for a magnetic flux jump type current limiting device, the seeding upper portion is processed to produce a cylindrical member. As a result, it is possible to shield several thousand gausses or more, which has been conventionally shown to have a shielding property of several tens of gausses at the liquid nitrogen temperature because of weak bonding in the crystal grain boundaries.

In addition, by adjusting the starting materials, RE
It is also possible to change the amount and size of RE ₂ BaCuO ₅ in Ba ₂ Cu ₃ O _7-x to control the critical current density value of the fault current limiter member. This applies to the current limiter that the critical current density value is changed by the addition of platinum and the control of the starting composition described in the improved QMG method. Conventionally, these methods have been used to create a high critical current density value. Conversely, in the case of a fault current limiter, the 211 phase is controlled to cause a magnetic flux jump at an arbitrary magnetic field value, and the critical current It can be applied to reduce the density value.

Further, as a flux jump type fault current limiter member, in order to prevent an increase in steady-state impedance due to a leakage magnetic field from a coil-shaped power transmission line wound on the outside of the cylinder, both ends of the superconducting cylinder are provided with flanged shields. By adding, a further high shield characteristic can be obtained. This brim-shaped shield body is processed by adding it to the precursor before partial melting, or after making a cylindrical shape, a brim-shaped member manufactured by the same method is replaced with a rare earth element to reduce the melting point of REB.
a ₂ Cu _7-x as a solder is inserted between the brim-shaped member and the tubular member, and even if it is heated to a temperature not lower than the melting temperature of the solder and not higher than the melting temperature of the member and joined, a flanged member having excellent shielding properties Can be produced.

The cross-sectional shape of the above-mentioned cylindrical member may be circular, polygonal, or the shape of the collar-shaped member may be circular, polygonal, or the like.

[0023]

Example 1 A cylindrical magnetic flux jump type fault current limiter member having an outer diameter of about 20 mm, an inner diameter of about 8 mm and a height of about 40 mm was produced by combining the proposed method with the improved QMG method. Y ₂ BaCuO ₅ is finely dispersed in this member, and YBa ₂ Cu ₃ O _7-x (123) and Y ₂ BaCuO
₅ (Y-211) is a single crystal granular bulk current limiting member having a molar ratio of 7: 3. In the case of this example, the crystal C-axis was made parallel to the axis of the cylinder.

The method for producing the member for the bulk current limiter, the components of the obtained bulk, the dispersion state of 211, and the method for obtaining the cylindrical shape will be described in detail below. The following commercially available powders, Y
₂ O ₃ , BaO ₂ , BaCuO ₂ , CuO, PtO ₂ are used, and these are Y-123 and Y-211 in a molar ratio of 7:
3 and Pt were weighed to be 0.5 wt% and kneaded with an automatic kneader for about 1 hour, and then shaped into a cylindrical shape having a diameter of 20 mm and a height of 40 mm using a mold. The molded powder is vacuum-sealed in a rubber bag and 2t / cm ² with a cold isostatic press.
Was applied to prepare a precursor. A hole having a diameter of 8 mm was drilled from the bottom of this cylindrical precursor, leaving 10 mm from the top. The thus-obtained columnar precursor with a single-ended hole was subjected to heat treatment in a box furnace in the same heat treatment pattern as in the modified QMG method so that Y-123 was grown from the partially melted state. During this heat treatment, S
The seed crystal of m-123 was placed so that the cleavage plane (ab plane) was in contact with the center of the upper surface of the cylindrical precursor in the partially molten state inside the box furnace. After this heat treatment, it was taken out at room temperature, transferred to an oxygen atmosphere tubular furnace, and subjected to oxygen addition treatment at 600 ° C. for 20 hours.

The superconductor thus produced has a critical current density of 3 when measured by a vibrating sample magnetometer (VSM).
The temperature was × 10 ⁴ A / cm ² , and the temperature was 92K when measured by AC susceptibility. The upper and lower surfaces and the side surfaces of this single-ended holed cylindrical bulk were polished and observed with a polarization optical microscope and a secondary electron scanning microscope (SEM), but no grain boundary was observed. Further, when the upper and lower surface portions were measured by Laue X-ray diffraction in the crystal axis direction, it was found that the longitudinal direction of the cylinder and the c-axis direction were parallel to each other. That is, it was found that the whole of the cylinder with one end bored by seeding was composed of a single crystal grain. When energy dispersive X-ray composition analysis was performed, the matrix was Y: Ba: Cu = 0.98: 2.
The atomic ratio was 02: 2.97. The average particle size of the 211 phase, which is the peritectic reaction residue, is 1 μm and is 0.5 to 5 μm.
And the volume fraction was about 27%. The center portion of the upper surface of the single-crystal open-ended bulk obtained as described above was cut with a diamond grindstone, a hole having a diameter of 8 mm was opened in the center portion, and the whole was penetrated to form a hollow cylinder with both ends opened. Hereinafter, this is referred to as member A.

For comparison, a polycrystalline bulk member B was prepared by using the same manufacturing process except that a seed crystal was not used. The upper and lower surfaces and a part of the side surface of the member B were polished and observed under a microscope. As a result, it was found that they were composed of polycrystals having an average grain size of about 5 mm. Evaluation of the shield characteristics of the magnetic flux jump type current limiting device obtained as described above,
The member A was placed in the bore of the superconducting solenoid magnet, and the shield characteristics were evaluated. The results at the liquid nitrogen temperature are shown in FIG. The result of the polycrystalline member B for comparison is also shown on the same drawing. In the case of the member B, almost no shielding effect was observed as shown in 8, and it can be seen that the magnetic field gradually entered. On the other hand, in the shield characteristic 7 of the member of the present invention, it can be seen that the external magnetic field is shielded with high efficiency up to 0.4 T, and the function as the flux jump type fault current limiter member is sufficiently satisfied.

In the case of the cylindrical member of the magnetic flux jump type fault current limiter, it is essential that the magnetic field breaks the shield and enters the inside to increase the inductance as a whole only when an excessive current flows. In the case of, it is obvious that the magnetic field enters the member from a certain magnetic field and cannot be used.

When the processing method of the precursor was changed, that is, a method of preparing a precursor with one end holed by the mold itself, or inserting a rod into a tube and removing the rod after hydrostatic pressure treatment, a precursor with one end holed was produced. Even in this case, the same results as in this example were obtained. As is clear from this, in order to manufacture the cylindrical member of the magnetic flux jump type fault current limiter, it is important that seeding is performed and the entire member is made of a single grain, and the effectiveness of the present invention is It could be confirmed.

In addition, Y ₂ O ₃ , BaO ₂ , BaCu
O ₂ , CuO and PtO ₂ are used, and Y-123 and Y-
211 is 9: 1 and 10: 0 in molar ratio and Pt is 0.
It was weighed so as to be 5 wt%, and the critical current density of the sample manufactured in the same manner as the above manufacturing method was measured. Molar ratio 9:
The critical current density of the sample of No. 1 is 1.5 × 10 ⁴ A / cm ² , and the critical current density of the sample of 10: 0 is 0.9 ×.
It was 10 ⁴ A / cm ² . The critical current density value can be controlled by controlling the starting mixed powder ratio. Since the magnetic field shield characteristics can be controlled by controlling the critical current density value, it was found that the method can be applied to the manufacture of flux jump type fault current limiter members.

(Example 2) A collared shape was produced in the same manner as in Example 1. The following commercially available powders, Y ₂ O ₃ , Ba
O ₂ , BaCuO ₂ , CuO, PtO ₂ was used, and these were weighed so that Y-123 and Y-211 were in a molar ratio of 7: 3 and Pt was 0.5 wt%, and then they were weighed in an automatic kneader for about 1 hour. After kneading, it was shaped into a cylindrical shape having a diameter of 25 mm and a height of 40 mm using a mold. Further, the molded powder was vacuum-sealed in a rubber bag, and a load of ² t / cm ² was applied by a cold isostatic press to prepare a precursor. A hole having a diameter of 8 mm was drilled from the bottom of this cylindrical precursor, leaving 10 mm from the top. Further, cutting was performed so that both ends had a brim shape as shown in FIG. The thus obtained flanged columnar precursor having a single-ended hole was subjected to Y-12 from a partially molten state in a box furnace in a heat treatment pattern similar to that of the improved QMG method.
Heat treatment was carried out so that 3 would grow. A seed crystal of Sm-123 was placed at about 1030 ° C. during the heat treatment so that the cleavage plane (ab plane) was in contact with the center of the upper surface of the columnar precursor in the partially molten state inside the box furnace. After this heat treatment, it was taken out at room temperature, transferred to an oxygen atmosphere tubular furnace, and subjected to oxygen addition treatment at 600 ° C. for 20 hours.

Further, in order to make a current limiting member, the center portion of the upper surface of the obtained single-ended granular bulk with a flanged shape is cut with a diamond grindstone, and the center portion has a diameter of 8 mm.
The hole was opened, and the whole was penetrated to form a flanged hollow cylinder with openings at both ends. When a coil was wound between the collars of this member and the shield characteristics were evaluated, it was confirmed that magnetic field leakage from both ends of the cylinder was less than that of a collarless member, and good shield characteristics up to 0.42T were obtained. It was

(Embodiment 3) After manufacturing a cylindrical magnetic flux jump type fault current limiter member by the same method as in Embodiment 1, the magnetic field leakage is applied to both ends of the cylindrical shape by using a joining method as described below. A collar made of Y123 for prevention was added. That is, the following commercially available powders, Y ₂ O ₃ , BaO ₂ , BaCuO ₂ , Cu
O and PtO ₂ are used, and these are Y-123 and Y-211.
Was weighed so that the molar ratio was 7: 3 and Pt was 0.5 wt% and kneaded with an automatic kneader for about 1 hour.
It was shaped into a cylindrical shape with a m and a height of 40 mm using a mold. Further, the molded powder was vacuum-sealed in a rubber bag, and a load of ² t / cm ² was applied by a cold isostatic press to prepare a precursor. A member precursor C was prepared by punching a hole having a diameter of 10 mm from the bottom of this cylindrical precursor, leaving 10 mm from the top. Further, a disk-shaped brim precursor D having an outer diameter of 30 mm and a thickness of 5 mm was produced by the above method. In the box-shaped furnace, the columnar precursor C and the disc-shaped precursor D thus obtained with a single-ended hole were
The heat treatment was performed in the same heat treatment pattern as in the modified QMG method so that Y-123 grew from the partially melted state. A seed crystal of Sm-123 was placed at about 1030 ° C. during the heat treatment so that the cleavage plane (ab plane) was in contact with the center of the upper surface of the columnar precursor in the partially molten state inside the box furnace. After this heat treatment, the members C and D were taken out at room temperature, transferred to an oxygen atmosphere tubular furnace, and subjected to oxygen addition treatment at 600 ° C. for 20 hours.

In order to make the current limiting member further, the center part of the upper surface of the obtained single-crystal granular bulk with a flanged shape (C) is cut with a diamond grindstone, and a hole having a diameter of 8 mm is formed in the center part. The hollow cylinder was opened, and the whole was penetrated to form a flanged hollow cylinder with openings at both ends. Similarly, the center part of two disk-shaped members D is cut with a diamond grindstone, and the center part has a diameter of 8 mm.
I made a hole. In order to join the two members without impairing the shielding property, YbBa ₂ Cu ₃ O _7-x sintered powder was inserted between the members as a solder, heated to 980 ° C. in a box furnace, and gradually cooled to room temperature. . By doing so, the solder was partially melted and the member was not melted, so that the crystal orientation of the member was succeeded by the solder part, and the bonding without crystal grain boundaries was possible. A coil is wound between the collars of the member produced in this way,
When the shield characteristics were evaluated, it was confirmed that the magnetic field leakage from both ends of the cylinder was smaller than that of the collarless member, and the same good shield characteristics as in Example 2 were obtained.

[0034]

As described above, the present invention realizes a magnetic flux jump type fault current limiter which has been theoretically possible but not possible with oxide superconductors. INDUSTRIAL APPLICABILITY The present invention provides a magnetic flux jump type current limiting device member which enables a current limiting action especially at a liquid nitrogen temperature, and has an extremely great industrial effect.

[Brief description of drawings]

FIG. 1 is a diagram showing basic components of a flux jump type current limiting device.

FIG. 2 is a cross-sectional view of a mold for producing the precursor of the present invention.

FIG. 3 is a cross-sectional view of a rubber tube mold for producing the precursor of the present invention.

FIG. 4 is a graph showing the magnetic shield characteristics of the magnetic flux jump type superconducting fault current limiter member of the present invention and the magnetic shield characteristics of a member without seeding.

FIG. 5 shows an example of a precursor of a magnetic flux jump type current limiting device with a collar according to the present invention.

[Explanation of symbols]

 1 Induction coil composed of copper winding 2 Hollow superconducting magnetic shield 3 High magnetic permeability core 4 Mold 5 Mold 6 Rubber tube 7 Magnetic shield property of the member of the present invention 8 Shield property of member without seeding

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsuyuki Kaiho 1-4-1 Umezono, Tsukuba-shi, Ibaraki Electronic Technology Research Institute (72) Inventor Kazuhiro Kyokawa 1-4-1 Umezono, Tsukuba-shi, Ibaraki Electronic technique (72) Inventor Masamoto Tanaka 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Inside Nippon Steel Corporation Advanced Technology Research Laboratories (72) Inventor Misao Hashimoto 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa (72) Inventor Katsuyoshi Miyamoto, 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Nippon Steel Co., Ltd., Advanced Technology Laboratory (72) Inventor, Mitsuru Morita Ida, Nakahara-ku, Kawasaki-shi, Kanagawa 1618 Nippon Steel Corporation Advanced Technology Research Laboratories (72) Inventor Eiichi Teshima 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Nippon Steel Advanced Technology Research Institute, Inc. (72) Inventor Keiichi Kimura 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Nippon Steel Corporation Advanced Technology Research Institute (72) Inventor, Shobayashi 1618 Ida, Nakahara-ku, Kawasaki-shi, Kanagawa Nippon Steel Corporation Advanced Technology Research Center

Claims (3)

[Claims] 1. A hollow superconducting shield member having a single crystal shape and REBa ₂ Cu ₃ finely dispersed in RE ₂ BaCuO _5.
R in REBa ₂ Cu ₃ O _7-x consisting of O _7-x system
A magnetic flux jump type superconducting fault current limiter shield member characterized in that the magnetic field shield characteristics are changed by changing the amount of E ₂ BaCuO ₅ . (Here RE is Nd, Sm, E
u, Gd, Dy, Y, Ho, Er, Tm, Yb, Lu means one or more elements selected from the group consisting of) 2. A RE-based seed crystal in which a raw material powder of REBa ₂ Cu ₃ O _7-x superconducting material is mixed and formed into a cylindrical shape with one end open, and then a rare earth is substituted when the unopened upper surface is in a semi-molten state. Flux jump characterized by producing a shield member with a hollow cylindrical single crystal grain by making the upper surface including the crystal growth start portion by drilling after growing the crystal orientation by the seeding method using Type current limiter member manufacturing method. 3. A flux jump type superconducting fault current limiter,
A flux jump type superconducting fault current limiter member characterized in that a flange-shaped shield member shape is added to both ends of a hollow shield member by processing or joining after molding to reduce loss due to a leakage magnetic field.