JPH05226707A - Current limiting conductor - Google Patents

Abstract

PURPOSE:To suppress the partial quenching of a current limiting conductor so as to improve quench propagation and prevent fusion by providing sections, where either the thickness or the width of a superconductor made zigzag is made smaller than other sections, at a plurality of places. CONSTITUTION:In case of letting a certain rated current flow to an oxide superconductor 2 in superconductive condition, the current flows to the oxide superconductor 2. But, if a short circuit or the like occurs in a circuit and an excessive current flows, the oxide superconductor 2 becomes a normal conductor, being quenched, and has low resistance. The current is suppressed by the resistance generated in the oxide superconductor 2, and it shows current limiting effect. At this time, the quenching occurs at the folding parts 2a and 2b which are thinner than the center 2c, and is propagated from the turn-down parts 2a and 2b at both ends to the center 2c. Accordingly, the quenching widens quickly to the whole, and also partial quenching is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current limiting conductor used in a current limiting device for limiting an excessive current such as a short circuit current using a superconductor.

[0002]

2. Description of the Related Art FIG. 10 shows, for example, JP-A-2-281765.
It is a current limiting element using a conventional oxide superconductor disclosed in Japanese Patent Laid-Open Publication No. 2003-242242. In the figure, 1 is a substrate, and 2 is an oxide superconductor arranged on the substrate 1. In this example, a Y-based oxide superconductor formed by a doctor blade method into a sheet and punched into a zigzag shape. It is the body. In addition, the display is shaded for clarity. 2a is an oxide superconductor 2
One of the folded portions, 2b, is the other folded portion of the oxide superconductor 2, and 2c is the central portion. For example, it has a structure in which an oxide superconductor having a cross section with a width of about 1.3 mm and a thickness of about 0.9 mm is bent to have a side length of about 30 mm. Figure 1
FIG. 1 is a side view of FIG. 10 viewed from the direction A.

Next, the operation will be described. When the oxide superconductor 2 carries a rated current in a superconducting state, the current flows through the oxide superconductor 2. However, if a short circuit accident occurs in the circuit and an excessive current flows, the oxide superconductor 2
Quenches into a normal conductor and has resistance. The current generated is suppressed by the resistance generated in the oxide superconductor 2, and the current limiting effect is exhibited.

[0004]

The conventional current limiting conductor is constructed as described above and its cross-sectional area is substantially constant over the entire length, but the critical current density varies. Therefore, when the oxide superconductor 2 is quenched, there is a problem that a part of the entire length of the oxide superconductor is quenched and spreads from there to the whole, which takes time. Further, there is a risk of fusing depending on the degree of input energy.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a current limiting conductor capable of suppressing local quenching of the current limiting conductor, improving quench propagation, and preventing fusing.

[0006]

The current-limiting conductor according to the present invention has a plurality of locations in which at least one of the thickness and the width of the superconductor formed in a zigzag shape is smaller than the other portions.

[0007]

The current-limiting conductor according to the present invention has a plurality of places where the thickness or width of at least a part of the superconductor formed in a zigzag shape is made smaller than the other parts and the cross-sectional area is made smaller. Smaller than other parts,
Quenching occurs from this portion, and the quenching propagates quickly to the entire superconductor. In addition, local quenching is suppressed and fusing is also prevented.

[0008]

EXAMPLES Example 1. FIG. 1 shows a side view of a current limiting conductor according to an embodiment of the present invention viewed from the direction A in FIG. In the figure, 1 is a substrate, 2 is an oxide superconductor arranged in a zigzag shape on the substrate 1, 2a is one folded portion of the oxide superconductor 2, and 2b is the other folded portion of the oxide superconductor 2. 2c shows the central part. In this example, the folded-back portions 2a and 2b are thinner than the central portion 2c.

Next, the operation will be described. When the oxide superconductor 2 carries a rated current in a superconducting state, the current flows through the oxide superconductor 2. However, if a short circuit accident occurs in the circuit and an excessive current flows, the oxide superconductor 2
Quenches into a normal conductor and has resistance. The current generated is suppressed by the resistance generated in the oxide superconductor 2, and the current limiting effect is exhibited. At this time, quenching occurs in the folded-back portions 2a and 2b which are thinner than the central portion 2c, and propagates from the folded-back portions 2a and 2b at both ends toward the central portion 2c. Therefore, the quench quickly spreads throughout and the local quench is suppressed.

2 to 4 show another embodiment. As shown in these figures, if the folded portions 2a and 2b are thinner than the central portion 2c, the same effect as that of the first embodiment can be obtained.

Further, in each of the above embodiments, the folded-back portion 2
Although both a and 2b are thinner than the central portion 2c, only one of the folded portions 2a and 2b may be used. Furthermore, it is also possible to provide every other row without providing a thin portion in all rows.

In each of the above embodiments, the thickness of the folded portions 2a, 2b is shown to be thin, but the central portion 2c may be thinner than the other portions as shown in FIG.

Embodiment 2. FIG. 6 shows a current limiting conductor according to a second embodiment of the present invention. In the figure, 1 is a substrate, 2 is an oxide superconductor arranged on the substrate 1, 2a is one folded portion of the oxide superconductor 2, and 2b is an oxide superconductor 2.
In the other folded-back portion, 2c indicates the central portion. In this example, the folded-back portions 2a and 2b are narrower than the central portion 2c.

Next, the operation will be described. When the oxide superconductor 2 carries a rated current in a superconducting state, the current flows through the oxide superconductor 2. However, if a short circuit accident occurs in the circuit and an excessive current flows, the oxide superconductor 2
Quenches into a normal conductor and has resistance. The current generated is suppressed by the resistance generated in the oxide superconductor 2, and the current limiting effect is exhibited. At this time, the quench occurs at the folded portions 2a and 2b which are narrower than the central portion 2c, and the folded portions 2 at both ends are
Propagate from a, 2b toward the central portion 2c. Therefore, quenching spreads quickly to the whole, local quenching is suppressed, and fusing can be prevented.

Another embodiment is shown in FIGS. FIG. 7 shows a structure in which the width is gradually narrowed from a position slightly closer to the folded-back portions 2a and 2b from the central portion 2c. FIG. 8 shows a structure in which the width is gradually reduced from the central portion 2c toward the folded-back portions 2a and 2b. In any case, the same effect as that of the second embodiment shown in FIG. 6 can be obtained.

In each of the above embodiments, the width of both of the folded back portions 2a and 2b is narrowed, but only one of the folded back portions 2a and 2b may be used. Further, it may not be provided in all the rows and may be arranged every other row.

In each of the above embodiments, the width of the folded portions 2a and 2b is narrowed, but FIG.
As shown in, the width of the central portion 2c may be narrower than the other portions.

In each of the embodiments shown in FIGS. 1 to 9 described above, one of the thickness and the width of the superconductor 2 is made smaller than the other portion, but both the thickness and the width may be made smaller. ..

Further, in each of the above embodiments, the case where the sheet-shaped oxide superconductor made by the doctor blade method is used is explained, but a bulk material may be used, or P
A thin film formed by a VD method, a CVD method, a sputtering method, an electrodeposition method or the like may be used.

[0020]

As described above, according to the present invention, since there are a plurality of places where at least one of the thickness and the width of the superconductor formed in a zigzag shape is smaller than the other portions, the critical current value is different. A plurality of places smaller than the portion of will be formed, and quenching will occur from these portions and the quenching will propagate quickly to the entire superconductor. In addition, local quenching is suppressed and fusing is also prevented.

[Brief description of drawings]

FIG. 1 is a side view showing a current limiting conductor according to a first embodiment of the present invention.

FIG. 2 is a side view showing a current limiting conductor according to another embodiment of the present invention.

FIG. 3 is a side view showing a current limiting conductor according to another embodiment of the present invention.

FIG. 4 is a side view showing a current limiting conductor according to another embodiment of the present invention.

FIG. 5 is a side view showing a current limiting conductor according to another embodiment of the present invention.

FIG. 6 is a top view showing a current limiting conductor according to a second embodiment of the present invention.

FIG. 7 is a top view showing a current limiting conductor according to another embodiment of the present invention.

FIG. 8 is a top view showing a current limiting conductor according to another embodiment of the present invention.

FIG. 9 is a top view showing a current limiting conductor according to another embodiment of the present invention.

FIG. 10 is a top view showing a conventional current limiting conductor.

FIG. 11 is a side view showing a conventional current limiting conductor.

[Explanation of symbols]

 1 Substrate 2 Oxide superconductor 2a One folded portion 2b Other folded portion 2c Central part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeru Matsuno 8-1-1 Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation Material Devices Research Center (72) Inventor Shinichi Kinouchi 8-1-1 Tsukaguchihonmachi, Amagasaki Mitsubishi Electric Devices Co., Ltd. Material Device Research Center

Claims (1)

[Claims] 1. A current limiting conductor having a plurality of locations in which at least one of the thickness and the width of a superconductor formed in a zigzag shape is smaller than other portions.