JP2975611B2 - Superconducting device current leads - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a current lead for a superconducting device,
The present invention relates to a current lead of a superconducting device in which a metal protective tube is arranged around a plurality of conductors through which a current flows.

[Prior Art] FIG. 3 shows, for example, the Journal of Cryogenic Engineering, “Cryogenic Engineering,” Vol.
o.2 (1973) is a current lead of the conventional superconducting device shown on page 69, in which the current lead (1) is
A metal protection tube (4) is provided on the outer periphery of the plurality of mesh wires (3) cooled by the cooling gas (2).

FIG. 2 shows the structure of a general superconducting device using one pair of the current leads (1) of FIG. 3, and immersed in liquid helium (7) in a power source (5) and in a cryogenic vessel (6). The superconducting coil (8) thus connected is operated by the current lead (1).

The current lead (1) is made of a material having a low electric resistance such as copper to form a mesh wire (3) for the purpose of increasing the surface area, is used as a current conductor, and is put into a protective tube (4). Heat generated by the conductor is a cooling gas (2)
Removed by Here, as described in the above-mentioned document, in order to minimize the amount of heat that enters the cryogenic part, the required cross-sectional area of the conductor (3) of the current lead (1) is determined by the conduction current and the length. There is an optimum value determined by the above, and usually design and manufacture are performed based on these values.

[Problems to be Solved by the Invention] The current lead of the conventional superconducting device as described above has a mesh wire (3) which is a conductor for the purpose of reducing the amount of heat entering a cryogenic part and reducing the mounting space. Is made as small as possible and the outer diameter of the protective tube (4) is also made small.

However, for devices that operate at 50 Hz and 60 Hz AC, such as the superconducting transformers and stator windings of superconducting generators that have recently been developed, superconducting coils (8)
And a high voltage of several kilovolts to several hundred kilovolts is applied to the current lead (1). On the other hand, since the current lead (1) is connected to a power supply (5) such as a transmission line outside the cryogenic vessel (6), it is necessary to reduce the electric field in the air.
The means for alleviating the electric field is to increase the outer diameter of the conductor. However, the outer diameter of the conventional current lead is small, and there is a risk of corona discharge due to the concentration of the electric field.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to reduce the electric field of a current lead portion and obtain a safe current lead of a superconducting device suitable for AC superconducting equipment without corona discharge. I do.

[Means for Solving the Problems] In a current lead of a superconducting device according to the present invention, the outer diameter of a protective tube is increased until it is within an allowable electric field of a voltage to be used, and a central tube in a central portion is arranged. By arranging a mesh wire between the central tube and the protective tube, the conductor cross-sectional area is the same as that of the related art. Further, the inside of the center tube is kept in a vacuum state or a material having a low thermal conductivity is inserted.

[Operation] In the present invention, since the outer diameter of the conductor portion is increased to reduce the electric field, there is no corona discharge, and the safety is improved.

[Embodiment] Fig. 1 shows an embodiment of the present invention, in which a central tube (10) is provided concentrically with a protective tube (4), and the protective tube (4) and the central tube (1) are provided.
0) are interposed between the mesh wire (3).

In addition, the same reference numerals as those in FIG. 3 denote the same parts. Generally, in an AC electric device, an allowable electric field of a lead portion between a lead and a ground plate is expressed by the following equation.

Here, V is the applied voltage, d is the distance from the center of the lead to the ground, and a is the radius of the lead.

If the current lead of the superconducting device is formed entirely inside the outer diameter 2a of the lead determined from these numerical values, the cross-sectional area of the conductor becomes excessive. Therefore, the outer diameter of the protective tube (4) is made the same as the outer diameter 2a of the lead, and the mesh wire (3) having a conductor cross-sectional area required inside the protective tube (4) is further centered on an extra portion inside the wire. A space (10) is arranged, and a vacuum or a material having a low thermal conductivity is inserted between the centers (10).

With this configuration, the outer diameter of the conductor (3) can be increased without increasing the cross-sectional area.

[Effects of the Invention] As described above, according to the present invention, the outer diameter of the protection tube is increased until the protection tube becomes a permissible electric field body of a voltage to be used, and the center tube is inserted into the center to protect the protection tube from the center tube. Since the mesh wire is installed between the tubes, the outer diameter is increased without increasing the conductor cross-sectional area, and the inside of the center tube is kept in a vacuum or a material with low thermal conductivity is inserted to reach the cryogenic part. The safe outer diameter of the AC superconducting device without corona discharge can be provided without increasing the amount of heat infiltration.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of one embodiment of the present invention, FIG.
FIG. 1 is a sectional view showing the structure of a conventional general superconducting device, and FIG. 3 is a cutaway perspective view of a current lead in FIG. (1) ... current lead, (2) ... cooling gas, (3) ...
... Mesh wire (conductor), (4) ... Protective tube, (10)
...... Central tube. In the drawings, the same reference numerals indicate the same or corresponding parts.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takuya Kishida 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Inside Kansai Electric Power Company (72) Inventor Akinori Ohara 8-1-1 Honcho Tsukaguchi, Amagasaki City, Hyogo Prefecture No. Mitsubishi Electric Corporation Central Research Laboratory (72) Inventor Tadatoshi Yamada 8-1-1 Tsukaguchi Honmachi, Amagasaki City, Hyogo Prefecture Mitsubishi Electric Corporation Central Research Laboratory (72) Inventor Masao Morita 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Prefecture No. 1 Inside Central Research Laboratory of Mitsubishi Electric Corporation (58) Field surveyed (Int. Cl. ⁶ , DB name) H01F 6 / 06,36 / 00 H01B 12/16

Claims (1)

(57) [Claims] 1. A protective tube made of a metal, a plurality of conductors through which a current flows, and a central tube concentric with the protective tube. The outer diameter of the protective tube is within an allowable electric field of a voltage using the protective tube. And the conductor is disposed between the central tube and the protective tube at the center, and the inside of the central tube is a current lead of a superconducting device which is formed by either vacuum or insertion of a low thermal conductivity material. .