JP3001805B2 - Superconducting current limiting element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting current limiting element used for suppressing a fault current or the like in a power supply system.

[0002]

2. Description of the Related Art When an accident such as a short circuit or a ground fault occurs in a power supply system, a very large current suddenly flows. If such an accident occurs, the system and the equipment will be seriously damaged unless the accident current is quickly suppressed. The current limiting element suppresses such a fault current and protects electric devices, wiring, and the like from damage. Among them, those applying superconducting-normal conduction transition of superconductors have been studied because the operating principle is simple and power loss during normal energization is small.

Further, a superconducting current-limiting element using an oxide superconductor as a superconductor can be cooled with liquid nitrogen, which is easier to handle, than a conventional current-limiting element using a metallic superconductor. Therefore, the oxide superconductor having a high resistivity in the normal conduction state and having a high critical current density (J _c ) of, for example, 10 ⁶ A / cm ² by thinning can be manufactured. This has the advantage that the current limiting element can be reduced in size. For these reasons, a superconducting current limiting element using an oxide superconductor has attracted attention.

In the current limiting method of the superconducting current limiting element, the current limiting start current value is set by the critical current value of the superconductor itself, and when the current value flowing through the power supply system exceeds the critical current value of the superconductor. The superconductor is transferred to the normal state
A method of performing current limiting by resistance generated by the transition to the normal state has been mainly studied. However, in such a current limiting method, it is difficult to cause the superconductor to undergo normal conduction transition in a wide area at the same time, causing an excessive temperature rise locally, and thus the current limiting superconductor itself may be burned out. is there.

[0005] Therefore, as shown in FIG. 10, for a current-limiting (overcurrent suppressing) superconductor 2 connected in series to a current-limiting power supply system 1, a heating current is applied via an insulating layer 3. The conductive materials 4, 4,...
Are provided with a separate power supply 5 for supplying a current to the conductive materials for heating 4, 4... When an overcurrent flows in the power supply system 1. An electric current is supplied from the power source 5 to the heating conductive materials 4, 4,.
A current-limiting method for simultaneously transitioning the current-limiting superconductor 2 to a normal conduction state in a wide area by this heat is being studied.

[0006]

However, in the superconducting current limiting element using the above-mentioned conductive material for heating, the dielectric breakdown between the conductive material for heating and the superconductor for current limiting becomes a problem. . That is, in order to suppress the fault current with a response time of less than millisecond required for the current limiting element, it is necessary to reduce the distance between the conductive material for heating and the superconductor for current limiting, for example, It is desirable that the thickness of the insulating layer interposed between them is 10 μm or less.
However, if the heating conductive material and the current-limiting superconductor are arranged close to each other via such a thin insulating layer, there is no voltage drop because the superconductor does not generate resistance during normal conduction.
Since the electric potential is equal, the dielectric breakdown does not occur between the current-limiting superconductor and the heating conductive material. However, when the overcurrent is suppressed (current-limiting), the current-limiting superconductor has, for example, several kV or more. Since a voltage is generated, which causes an excessive potential difference between the current-limiting superconductor and the heating conductive material, there is an extremely high risk of dielectric breakdown.

In view of the above, in a conventional superconducting current limiting element using a conductive material for heating, for example, a normal-current transition of the current-limiting superconductor is performed by the conductive material for heating with a response time of less than millisecond. It is an object to suppress the dielectric breakdown between the current-limiting superconductor and the heating conductive material without obstructing the current.

SUMMARY OF THE INVENTION The present invention has been made in order to solve such a problem, and maintains a response time of, for example, milliseconds or less by a current-limiting superconductor, and then establishes a connection between the current-limiting superconductor and a heating current during current limiting. It is an object of the present invention to provide a superconducting current limiting element that enables suppression of dielectric breakdown between a conductive material and a conductive material.

[0009]

A superconducting current limiting element according to the present invention is arranged close to the current limiting superconductor via an insulating layer and a current limiting superconductor connected in series to a power supply system for current limiting. A heating power supply for supplying a current to the heating conductive material when an overcurrent occurs in the power supply system and causing the current-limiting superconductor to transition to a normal conduction state. The heating conductive material and the current-limiting superconductor are connected so that the current of the power supply system is divided into the heating conductive material during the flow operation.

In the superconducting current limiting element of the present invention, the heating conductive material and the current limiting superconductor are connected so that the current of the power supply system is divided into the heating conductive material during the current limiting operation. Therefore, the potential difference generated between the current-limiting superconductor and the heating conductive material during the current-limiting operation can be reduced. Thereby, even when the insulating layer between the current-limiting superconductor and the heating conductive material is made thin so as to realize a response time of, for example, milliseconds or less, the current-limiting superconductor and the heating conductive material are Can be suppressed.

[0011]

Embodiments of the present invention will be described below.

FIG. 1 is a diagram showing a schematic configuration of an embodiment of a superconducting current limiting element according to the present invention, wherein FIG.
(B) is a figure which shows the partial cross section typically. In FIG. 1, reference numeral 11 denotes a current-limiting superconductor. The current-limiting superconductor 11 is connected to a power supply system that performs current limiting, that is, a power supply system 12 that suppresses an overcurrent (accident current) generated at the time of an accident such as a short circuit or a ground fault. , Terminal T in series. The power of the power supply system 12 is supplied through the current-limiting superconductor 11 which is normally in a superconducting state.

As the current-limiting superconductor 11, a current-limiting superconductor having a resistance sufficient for current-limiting when viewed from the power supply system 12 when transitioning to the normal conduction state is used. Examples of such a current-limiting superconductor 11 include a thin film and a bulk of an oxide superconductor. In particular, Y-Ba-Cu-O-based, Bi-Sr-Ca-
Cu-O system, Tl-Ba-Ca-Cu-O system, Hg-B
It is preferable to use a thin film of an oxide superconductor having a critical temperature of 77 K or more, such as an a-Cu-O-based or Nd-Ba-Cu-O-based. This is because a large critical current density can be obtained relatively easily. Oxide superconductor thin films can be prepared, for example, by reactive sputtering, reactive evaporation, laser evaporation, CVD, M
It can be obtained by forming a film on an oxide single crystal or polycrystalline substrate by an OCVD method or the like.

As will be described later, in the present invention, the current-limiting superconductor 11 is caused to transition to the normal conduction state by the heat generation of the conductive material 14 for heating. It is necessary to set a large current value.

On the current-limiting superconductor 11 described above, a heating conductive material 14 is disposed close to the current-limiting superconductor 11 via an insulating layer 13. The heating conductive material 14 heats the current-limiting superconductor 11 at the start of current-limiting and causes the current-limiting superconductor 11 to transition to a normal conduction state. It is preferable to provide a plurality of heating conductive materials 14 as shown in FIG. 1 or to use a heating conductive material 14 spread in a plane as shown in FIG. The superconducting current limiting element shown in FIG. 2 has the same configuration as that of FIG. 1 except that the form of the heating conductive material 14 is different. Hereinafter, this embodiment will be described based on FIGS. Will be described.

In view of the above, most of the heating conductive material 14 is provided with the current-limiting superconductor 11 via the insulating layer 13.
It is preferable that 80% or more is in contact. In addition, this current-limiting superconductor 1
It is preferable that the portion in contact with 1 includes most of the current-limiting superconductor 11 to be changed to the normal conduction state, specifically, 90% or more.

The insulating layer 13 is made of a conductive material 14 for heating.
It is necessary to reduce the thickness so that overcurrent can be suppressed with a response time of less than millisecond required for the current limiting element, so that heat transfer from the current limiting element 11 to the current limiting superconductor 11 is performed well. Therefore, the specific thickness is preferably about 1 to 100 μm. Furthermore, it is desirable that the thickness of the insulating layer 13 be 10 μm or less as described above.

A plurality of heating conductive materials 1 shown in FIG.
Some of 4, 14,... Are connected via terminals H to projecting terminal connecting portions 11a provided on the side surfaces of the current-limiting superconductor 11. The same applies to the planar heating conductive material 14 shown in FIG. By connecting the heating conductive material 14 and the current limiting superconductor 11 in this way, the current of the power supply system 12 can be diverted to the heating conductive material 14 during the current limiting operation.

As shown in FIG. 1, when a plurality of heating conductive materials 14 are used, the number thereof is not particularly limited, but preferably, an overcurrent is applied to the heating conductive material 3 during current limiting. When the flow is divided, a plurality of conductive materials for heating 14, 1
4. Arranged so that a potential difference occurs between them. In addition, as shown in FIG. 2, when a planar conductive material for heating 14 is used, it is preferable that a potential difference is generated inside the conductive material.

The heating power supply 15 is provided separately from the power supply of the power supply system 12, and is configured to operate by an overcurrent sensor 16 provided in the power supply system 12. That is, an overcurrent (accident current) flows due to an accident such as a short circuit or ground fault in the power supply system 12, and the heating power supply 15 is turned on when the overcurrent sensor 16 detects the overcurrent. Have been. Reference numeral 17 denotes a power supply line for supplying a current from the heating power supply 15 to the heating conductive material 14;
Is a control line for the heating power supply 15.

The operation of the above-described superconducting current limiting element will be described. First, at the time of normal energization, the power of the power supply system 12 is supplied through the current-limiting superconductor 11 in a superconducting state, and no voltage is generated in the current-limiting superconductor 11. Since the reference numeral 15 is also off, the dielectric breakdown does not occur in the insulating layer 13 between the current-limiting superconductor 11 and the heating conductive material 14.

On the other hand, when an overcurrent such as a short-circuit current flows through the power supply system 12 and the overcurrent sensor 16 detects the overcurrent and the heating power supply 15 is turned on, the heating power supply 15 supplies the heating conductive material. Current flows through 14. Therefore, the heating conductive material 14 generates heat due to Joule heat, and due to this heat, the current-limiting superconductor 11 instantaneously enters a normal conduction state over a wide area, and an overcurrent is suppressed.

At the same time, the power supply system 1 is connected to the heating conductive material 14 due to the voltage generated in the current-limiting superconductor 11.
2 shunts. By shunting the system current to the heating conductive material 14 during this current limiting operation, the current limiting superconductor 1
1 and the heating conductive material 14 can be reduced in potential difference.

That is, as shown in FIG. 1, when a plurality of heating conductive materials 14, 14,... Are used, the potential difference between the heating conductive materials 14, 14,. , And a potential difference between the current-limiting superconductor 11 and each of the heating conductive materials 14, 14,. Further, as shown in FIG. 2, when the planar heating conductive material 14 is used, a potential difference is generated inside the heating conductive material 14, and the current-limiting superconductor 11 and the heating conductive material 14 are used.
And the potential difference between the two hardly occurs. Therefore, while maintaining the response time of the overcurrent suppression by the current-limiting superconductor 11 at, for example, milliseconds or less, the insulating layer 13 between the current-limiting superconductor 11 and the heating conductive material 14 during the current-limiting operation. It is possible to suppress dielectric breakdown.

As described above, during the current limiting operation, the power system 1
2 is diverted to the conductive material 14 for heating, the superconducting current-limiting element 11 is configured in both the normal energizing state and the current-limiting operation.
Since it is possible to suppress dielectric breakdown between the superconducting current limiting element and the heating conductive material 14, it is possible to use the superconducting current limiting element stably and repeatedly.

Next, another embodiment of the superconducting current limiting element according to the present invention will be described with reference to FIGS. The superconducting current limiting element shown in FIGS. 3 and 4 is a conductive material (hereinafter, referred to as a conductive material) whose resistance is increased by a temperature increase and arranged in parallel at a position electrically insulated from the current limiting superconductor 11.
(Referred to as a conductive material for resistance) 19. The conductive material for resistance 19 controls the branching of the system current to the conductive material for heating 14. Conductive material for resistance 19
For example, an oxide superconductor similar to the current-limiting superconductor 11 can be used.

The insulating layer 13 is formed of the current-limiting superconductor 11.
And a plurality of heating conductive materials 14, 14,... (Over the current-limiting superconductor 11 and the resistance conductive material 19 via the insulating layer 13). 3) or a planar heating conductive material 14 (FIG. 4) is provided.

The current-limiting superconductor 11 of this embodiment includes:
A protruding terminal connection portion 11a is provided on the side surface, and a similar protruding terminal connection portion 19a is provided on the conductive material 19 for resistance. Each of the plurality of heating conductive materials 14 shown in FIG. 3 has one end connected to the current-limiting superconductor 11 via a terminal H, and the other end connected to the conductive material 19 for resistance. '. In other words, the current-limiting superconductor 11 and the resistance conductive material 19 are connected by the heating conductive material 14. A similar connection structure is also applied to the planar heating conductive material 14 shown in FIG.

The heating power source 15 is connected to the current limiting superconductor 11 and the conductive material 19 for resistance, respectively, by terminals Ht and Ht.
Ht '. However, terminals Ht and H
t ′ may be a common terminal using one or more of the terminals H and H ′.

Except for these, the structure is the same as that of the superconducting current limiting element shown in FIGS. 1 and 2, and the same parts are denoted by the same reference numerals.

The operation of the above-described superconducting current limiting element will be described. First, at the time of normal energization, FIGS.
Similarly to the superconducting current limiting element shown in FIG. 1, the power of the power supply system 12 is supplied through the current limiting superconductor 11 in the superconducting state, no voltage is generated in the current limiting superconductor 11, and the heating power supply Since the reference numeral 15 is also off, the dielectric breakdown does not occur in the insulating layer 13 between the current-limiting superconductor 11 and the heating conductive material 14.

On the other hand, an overcurrent such as a short-circuit current flows through the power supply system 12, and when the overcurrent sensor 16 detects the overcurrent and the heating power supply 15 is turned on, the current-limiting superconductor 11 and the conductive material for resistance are turned on. 19, and a current flows through the conductive material for heating 14. Therefore, the heating conductive material 14 generates heat due to Joule heat, and due to this heat, the current-limiting superconductor 11 instantaneously enters a normal conduction state over a wide area, and an overcurrent is suppressed. At the same time, the temperature of the conductive material for resistance 19 also rises, the resistance changes, and a high resistance state is set.

Further, at the same time as the temperature of the current limiting superconductor 11 and the resistance conductive material 19 rise, the system current is shunted to the heating conductive material 14 due to the voltage generated in the current limiting superconductor 11. The system current is also shunted to the conductive material for resistance 19 through the conductive material for heating 14, whereby the potential difference between the current-limiting superconductor 11 and the conductive material for heating 14 can be reduced.

That is, as shown in FIG. 3, when a plurality of conductive materials for heating 14 are used, the system current is distributed to the conductive material for resistance 19 through the conductive material for heating 14. , And a potential difference is generated between the heating conductive materials 14, 14..., So that a potential difference between the current-limiting superconductor 11 and each heating conductive material 14, 14. In addition, as shown in FIG. 4, when a planar heating conductive material 14 is used, a potential difference is generated inside the heating conductive material 14, which causes a gap between the current-limiting superconductor 11 and the heating conductive material 14. Almost no potential difference occurs.

The resistance conductive material 19 has a low resistance so that a sufficient current can flow through the heating conductive material 14 at the start of the current limiting so that the current limiting superconductor 11 enters a normal conduction state. In the current limiting operation, the heating conductive material 1
4 has a role of reliably shunting overcurrent from the power supply system 12. As a result, a plurality of heating conductive materials 1
A potential difference is generated between 4, 14... Or inside the planar heating conductive material 14, so that a potential difference between the current-limiting superconductor 11 and the heating conductive material 14 hardly occurs. it can. In addition, the resistance becomes high during the current limiting operation, and the resistance becomes sufficient as viewed from the power supply system 12, so that the effect of suppressing the overcurrent is exerted.

As described above, in the superconducting current limiting element of this embodiment, the response time of the overcurrent suppression by the current limiting superconductor 11 is maintained at, for example, milliseconds or less, and then the current limiting superconductor is operated during the current limiting operation. It is possible to more reliably suppress dielectric breakdown of the insulating layer 13 between the heating layer 11 and the conductive material 14 for heating. Therefore, it becomes possible to use the superconducting current limiting element stably and repeatedly.

In each of the above-described embodiments, the case where the heating power supply 15 independent of the power supply system 12 is used has been described. For example, as shown in FIG. (Hereinafter, referred to as a magnetic circuit type heating power supply) 20 for obtaining the above.

In FIG. 5, A denotes a current-limiting superconductor 1.
1, the current-limiting element body having the heating conductive material 14 and the like is omitted, and has the same configuration as that of FIGS. 1 and 2 or FIGS. The current supply line 17 connected to the magnetic circuit type heating power supply 20, that is, the power supply line of the heating conductive material, is the same as the above-described embodiments, and is made of the heating conductive material or the current-limiting superconductor 11 and the resistor. The terminals Ht and Ht 'of the conductive material 19 are connected.

A specific configuration example of the magnetic circuit type heating power supply 20 will be described with reference to FIG. The magnetic circuit type heating power supply 20 has a magnetic core 22 around which a power supply system 12 is wound via a ring-shaped magnetic shield superconductor 21. The magnetic core 22 includes the power supply system 12 and the magnetic circuit. The power supply line 17 made of a conductive material for heating is wound so as to form the following.

Here, a current flows through the magnetic shielding superconductor 21 so that a magnetic field is not generated in the magnetic core 22 during normal energization. As a result, when viewed from the power supply system 12, there is almost no inductance due to the magnetic circuit, and no current flows through the heating conductive material. The current-limiting start current value is set by the critical current value of the ring-shaped magnetic shielding superconductor 21.
The power system 12 has such a current that the magnetic field 1 cannot shield the magnetic field.
When the overcurrent to be supplied to the power supply system 12 flows, that is, when the magnetic core 22 is magnetized, a current flows through the power supply line 17 of the heating conductive material, and as a result, the current flows through the heating conductive material. Supplied. Thus, the current limiting operation is started in the same manner as in the above-described embodiments.

In the magnetic circuit type heating power supply 20 having the above-described structure, an unnecessary current is prevented from flowing through the heating conductive material, and the current limiting superconductor or the current limiting superconductor and the resistance are controlled. It is preferable to set the value of the magnetic saturation of the magnetic core 22 so as to obtain a current sufficient and sufficient to bring the conductive material into a normal conduction state. FIG. 7 shows a configuration example of another magnetic circuit type heating power supply.
The magnetic core 23 includes a core portion 23a having a small saturation magnetic flux and a core portion 23b having a large saturation magnetic flux. The power supply system 12 is wound so as to be non-inductive while the core portion 23 is not magnetically saturated. I have. Therefore, no current flows through the power supply line 17 while the magnetic flux generated by the coil of the power supply system 12 does not exceed the saturation magnetic flux of the core portion 23a. On the other hand, when an overcurrent flows and the magnetic flux generated by the power supply system 12 exceeds the saturation magnetic flux of the core portion 23a, the non-inductive condition is broken, the current flows through the power supply line 17, and the current is supplied to the heating-like conductive material. Flow begins.

As described above, the magnetic circuit type heating power supply 20 is composed of the heating power supply 15 and the overcurrent sensor 1 of each of the above-described embodiments.
6, which greatly contributes to the reduction of the number of components, and has the effect of generating an inductance in the power supply system line when an overcurrent flows, thereby playing a part in suppressing the overcurrent.

[0043]

Next, specific examples of the present invention will be described.

Embodiment 1 Embodiment 1 is a specific example of the superconducting current limiting element shown in FIG. Five heating conductive materials 14 were used, and the same superconducting material as the current limiting superconductor 11 was used as the resistance conductive material 19 whose resistance varies with temperature.

First, a 1 μm-thick Y—Ba—Cu—O layer was formed on a 100 × 100 mm SrTiO ₃ substrate by sputtering.
By depositing a thin oxide superconductor thin film and patterning it by photolithography,
A current-limiting superconductor 11 having a width of 70 mm and a conductive material 19 for resistance having a width of 10 mm were formed in parallel with the current-limiting superconductor 11 by 5 mm. Note that five terminal connection portions 11a and 19a were formed at intervals of 5 mm. The shape of each terminal connection part 11a, 19a is 5 × 5
mm.

The terminals H and H 'of the current-limiting superconductor 11, the conductive material 19 for resistance and the conductive material 14 for heating are
After depositing 200nm of silver, 673K in 1 atmosphere of oxygen atmosphere
For 10 minutes. The center terminal of the terminals H and H 'is a common terminal with the terminals Ht and Ht', respectively. Next, on the current-limiting superconductor 11 and the conductive material 19 for resistance, a 500-nm-thick MgO film was formed as an insulating layer 13 at locations other than the terminal connection portions 11a and 19a.

On this insulating layer 13, a width of 5 mm and a thickness of 100 nm
Of silver was deposited between the terminals H and H 'to form a conductive material 14 for heating. The resistance of one heating conductive material 14 is about
It was 0.1Ω. The terminals T of the power supply system 12 were prepared by vapor deposition and heat treatment of silver in the same manner as the terminals H and H ', and the power supply system 12 was connected by silver paste. 77K
Current Limiting Superconductor 11 and Resistive Conductive Material 1
The critical current density of the oxide superconductor thin film as 9 is 3 × 10
^{It was 6} A / cm ² .

The above-mentioned superconductor current limiting element was cooled with liquid nitrogen, and a current limiting test was performed as follows. The current limiting start current was set to 300 A, an external power supply was used as the heating power supply 15, and the output voltage was set to 20V. The test was performed by using a power supply having a maximum inter-terminal voltage of 1 kV and an internal resistance of 1Ω as the power supply system 12, and turning on the heating power supply 15 when the current exceeded 300A to evaluate the current limiting characteristics.
FIG. 8 shows the current limiting characteristics at this time. The horizontal axis is the time measured in milliseconds, and the vertical axis is the current value measured in amps. The heating power supply 15 was turned on at the arrow in the figure.

In this case, the critical current value of the current-limiting superconductor 11 when current is not supplied to the heating conductive material 14 is 600 A, and the current limiting is not started at the set current limiting starting current of 300 A. In addition, it took about 1 millisecond from when the heating power supply 15 was turned on until the current limiting was started, and thereafter, within several milliseconds, a resistance of approximately 3Ω was generated, and the current limiting was performed. No dielectric breakdown occurred in the current limiting test, and the superconducting current limiting element itself was not damaged. Even after performing the same test 10 times, the characteristics did not change, and no damage to the element itself was observed.

On the other hand, as a comparative example with the present invention, the superconducting current limiting element shown in FIG. 10 was manufactured using the same oxide superconductor material and heating conductive material. The superconducting current limiting element shown in FIG. 10 differs from the present invention in that the current limiting superconductor and the conductive material for heating are not electrically connected. Using such a superconducting current-limiting element, a current-limiting test similar to that of Example 1 was performed. As a result, dielectric breakdown occurred in several places in the insulating layer 3 at the start of current-limiting, and local burning occurred. It could not be used repeatedly.

Embodiment 2 This embodiment 2 is a specific example of the superconducting current limiting element shown in FIGS. A superconducting current limiting element was produced in the same manner as in Example 1 except that a magnetic circuit type heating power supply 20 shown below was used as a heating power supply.

The magnetic circuit type heating power supply 20 has a saturation magnetic field.
A circular iron core with 0.5 T, relative permeability of 800 and radius of 30 mm was used, and the size of the magnetic path was 200 mm in both length and width. As the superconductor 21 for magnetic shielding, a cylindrical Bi-based oxide superconductor having an inner diameter of 33 mm and an outer diameter of 40 mm was used. The size of the cylindrical Bi-based oxide superconductor was set so that when the superconductor was 77K, a current of 300 A flowed through the power supply system 12 and the magnetic shielding ability was lost. Regarding the number of turns of the coil, the power supply system 12 is wound 100 times on the superconductor 21 for magnetic shield,
The power supply line 17 side of the conductive material for heating was wound 10 times.

The current limiting characteristic evaluation test was performed by cooling the magnetic circuit portion with liquid nitrogen and applying an overcurrent under the same conditions as in Example 1. FIG. 9 shows the characteristics. As can be seen from FIG. 9, when the current value exceeds 300 A, current limiting is started, and the heating conductive material 14 generates heat. Also, it can be seen that a sufficient current limiting is performed within a few milliseconds. Even in this test, dielectric breakdown did not occur, and a repetitive operation could be performed.

[0054]

As described above, according to the superconducting current limiting element of the present invention, while maintaining a response time of, for example, milliseconds or less, an excessively large current flows between the current limiting superconductor and the heating conductive material. It is possible to prevent the occurrence of a large potential difference and dielectric breakdown, and it is possible to repeatedly perform the current limiting operation. Therefore, it is possible to provide a superconducting current limiting element which has excellent current limiting characteristics and is highly practical and can be used repeatedly.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a schematic configuration of a superconducting current limiting element according to an embodiment of the present invention.

FIG. 2 is a view schematically showing a modification of the superconducting current limiting element shown in FIG.

FIG. 3 is a diagram schematically showing a schematic configuration of a superconducting current limiting element according to another embodiment of the present invention.

FIG. 4 is a diagram schematically showing a modification of the superconducting current limiting element shown in FIG.

FIG. 5 is a diagram showing a schematic configuration of an embodiment using a magnetic circuit type heating power supply as a heating power supply.

6 is a diagram showing a configuration example of a magnetic circuit type heating power supply shown in FIG. 5;

7 is a diagram showing another configuration example of the magnetic circuit type heating power supply shown in FIG.

FIG. 8 is a diagram illustrating current limiting characteristics of the superconducting current limiting element according to the first embodiment.

FIG. 9 is a diagram illustrating current-limiting characteristics of a superconducting current-limiting element according to a second embodiment.

FIG. 10 is a diagram showing a schematic configuration of a conventional superconducting current limiting element.

[Explanation of symbols]

 11 ... current-limiting superconductor 12 ... power supply system 13 ... insulating layer 14 ... heating conductive material 15 ... heating power supply 16 ... overcurrent sensor

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-223790 (JP, A) JP-A-1-190219 (JP, A) JP-A 1-248931 (JP, A) JP-A 5- 176450 (JP, A) JP-A-62-244410 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 39/00-39/02 H01L 39/22-39/24 H02H 9/02

Claims (2)

(57) [Claims] 1. A current-limiting superconductor connected in series to a current-limiting power supply system, a heating conductive material disposed close to the current-limiting superconductor via an insulating layer, and A heating power supply for supplying a current to the heating conductive material when a current is generated to cause the current-limiting superconductor to transition to a normal conduction state. A superconducting current-limiting element, wherein the heating conductive material and the current-limiting superconductor are connected so as to diverge into a conductive material. 2. The superconducting current limiting element according to claim 1.
And further electrically insulated from the current-limiting superconductor.
In parallel with each other, and
A conductive material for resistance having increased resistance;
One end of the conductive material is connected to the current-limiting superconductor,
Are connected to the conductive material for resistance.
Superconducting current limiting element.