JP2906866B2 - Superconducting twisted wire for AC - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current supply system for a superconducting stranded AC wire.

[0002]

2. Description of the Related Art An AC superconducting wire has a stranded wire structure in which a number of strands having a multifilamentary ultrafine filament structure are twisted. Conventionally, a superconducting stranded wire is energized by a connection such that a current flows into the entire stranded wire.

[0003]

The alternating current flowing through the wires arranged at the center of the AC superconducting stranded wire has an opposite phase to the main current, and the influence of the magnetic field of each wire current causes The critical current capacity of the superconducting stranded twisted wire for alternating current is greatly reduced rather than the number of twisted wires of the critical current value of the single strand constituting the wire. The present invention provides an energization method that reduces this reduction and increases the critical current capacity of the AC superconducting stranded wire.

[0004]

According to the present invention, of the strands of a superconducting stranded AC alternating wire, both ends of a strand arranged at a central portion are separated from other strands and drawn out. Disconnect from the connection and short-circuit externally.

[0005]

The magnitude of the alternating current flowing through each strand of the AC superconducting stranded wire is determined by the self-inductance of each strand and the magnitude of the mutual inductance between the strands. The wire current arranged at the center of the alternating current superconducting stranded wire has an opposite phase to the other wire currents due to the mutual induction action of the other wire currents.

Therefore, when all the strands are connected together and energized, the critical current capacity of the entire AC superconducting stranded wire is reduced. For this reason, it is also effective to use an alternating current superconducting stranded wire having a cross-sectional structure in which no strand is arranged at the position of the center portion of the alternating current superconducting stranded wire.

However, the current in the opposite phase at this position acts in such a direction as to cancel the magnetic field of each of the other strand currents.
This has the effect of increasing the critical current value of each of the other strands. According to the method of the present invention, the main current does not flow through the wire at this center position,
By flowing a current having the opposite phase induced by each of the other strand currents, the magnetic field applied to each of the other strands is reduced, and the critical current value is increased.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1A shows a sectional structure of an AC superconducting wire according to a first embodiment of the present invention. In the first embodiment, the element wire × 7
It is a superconducting stranded wire for alternating current having a main stranded wire structure, and numbered 1a to 1 in the drawing.
1 g indicates each strand. FIG. 1B shows a sectional structure of an AC superconducting wire according to a second embodiment of the present invention. Example 2 is a case of an AC superconducting stranded wire having an element wire × 7 × 7 twisted and stranded wire structure.
g) are the strands (1a to 1g) to (7a to 7), respectively.
g) is a seven-stranded wire, which is a primary stranded wire, and further has a seven-stranded wire structure.

In the figures, the wires (1a to 1g) to (7a to
If all the numbers of 7g) are described, it becomes complicated. For only the primary stranded wire 3 (3a to 3g), the configuration is expanded horizontally to show the element wire numbers 3a to 3g. Other primary twisted wires are omitted as equivalent.

In FIG. 1A, the wire 1a is
In (b), the seven strands 1a to 1g included in the primary stranded wire 1 (1a to 1g) are the strands respectively arranged at the center of the AC superconducting stranded wire. That is, although the strand 1a in the stranded wire structure of FIG. 1A has strands 1b to 1g twisted around the strand, this strand 1a can be applied to any cross section in the longitudinal direction of the AC superconducting stranded wire. The strand is located at the center position, that is, located at the center position of the AC superconducting stranded wire.

Similarly, the seven strands 1a to 1g included in the primary stranded wires 1 (1a to 1g) in the stranded structure of FIG.
Has primary twisted wires of numbers 2 (2a to 2g) to 7 (7a to 7g) twisted around, and these strands 1a to 1g
Is a wire located at the center position in any cross section in the length direction of the AC superconducting stranded wire, that is, a wire arranged at the center position of the AC superconducting stranded wire. 1C shows both ends of the strand 1a in the stranded structure of FIG. 1A, and FIG.
Primary stranded wire 1 (1a to 1g) in the twisted and stranded wire structure (b)
FIG. 4 is a schematic diagram showing that both ends of seven strands 1a to 1g are separated from the main circuit connection and short-circuited outside.

FIG. 2 shows a decrease in the critical current Ic when a magnetic field B is further applied to the AC superconducting stranded wire in the case of the above-described second embodiment.
When the strands 1a to 1g are not connected externally, the critical current value in an own magnetic field at an external magnetic field of zero when the external wire is zero, Ic2 is 7
It is a measurement example showing a critical current value in a self-magnetic field at an external magnetic field of zero when the strands 1a to 1g are connected outside. As shown in the case of zero external magnetic field in the figure, the critical current value is greatly improved from Ic1 to Ic2.

[0013]

As described above, the critical current of the AC superconducting stranded wire can be greatly improved by the method of the present invention.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an energization method for an AC superconducting stranded wire according to the present invention.

FIG. 2 is a diagram showing an effect of a current supply method of a superconducting stranded AC wire according to the present invention.

[Explanation of symbols]

1a-1g Each strand when the AC superconducting stranded wire is 7 strands 1 (1a-1g) Primary stranded wire when the AC superconducting stranded wire is 7 × 7 twisted strands 2 (2a-2g) ３3 (3a-3g) 〃4 (4a-4g) 〃5 (5a-5g) 〃6 (6a-6g) 〃7 (7a-7g) 〃

Claims (1)

(57) [Claims] An end of a strand disposed at a center portion of each strand of an AC superconducting twisted wire is separated from another strand and pulled out, and is separated from a main circuit connection and short-circuited outside. AC superconducting stranded wire energizing method.