JPH0785734A - Superconducting bus bar - Google Patents

Abstract

PURPOSE:To provide a superconducting bus bar having high electrical insulation in which movement of a superconductor due to electromagnetic force is prevented and cooling of the superconductor is improved, by improving the structure of a core. CONSTITUTION:A cryogenic regrigerant 5 flows inside a hollow tube 4 (e.g. a copper pipe) containing superconductors 1, 2 therein. A spacer 6 is interposed between the superconductors 1, 2 and the inner surface of the hollow tube 4. The hollow tube 4 is covered with an electrically insulating layer 3, which is covered with an earth electrode layer 7. Two cores such constituted as above are bundled with, e.g. a glass tape 8. The spacer 6 is conductive or semiconductive. A plurality of the cores are preferably bundled with a conductive or electrically insulative tape material or wire rod.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting busbar which is provided with measures for preventing movement of the superconducting conductor due to electromagnetic force, has good cooling of the superconducting conductor, and has high electric insulation performance.

[0002]

2. Description of the Related Art In a superconducting bus bar, an electromagnetic repulsive force acts between a conductor in the forward direction of current and a conductor in the reverse direction. This force increases in proportion to the square of the current. For example, in the case of a superconducting busbar for a large magnet and the energizing current is several tens of kA, the magnitude is 1 to several tons per 1 m of the conductor of the superconducting busbar. Also reaches. In response to such electromagnetic repulsive force, when the superconducting conductor can move freely mechanically, the superconducting conductor is subjected to mechanical stress each time the amount of electric current changes,
There is a risk of deterioration and disconnection due to friction, and there is a problem that the temperature of the superconducting conductor rises due to the frictional heat caused by the movement, and the superconducting layer is quenched so that the superconducting state cannot be maintained.

In order to solve the problem caused by such an electromagnetic repulsive force, a conventional superconducting bus bar, as shown in FIG. 3, has a rectangular superconducting conductor for each of forward and reverse current conductors (1) (2). ) Is sandwiched between electrical insulators (3) and bundled together with a glass tape (8), whereby both conductors are fixed and a cryogenic refrigerant is circulated around them to maintain a superconducting state. Has been adopted.

[0004]

By the way, the conventional structure as shown in FIG. 1 has the following problems. Since both conductors are very close to each other, the electrical insulation between them is weak, especially in the creeping direction. Since both conductors are close to each other and the electric insulation layer (3) and the glass tape (8) as a binding layer for electromagnetic force protection cover the conductor surface, the surface area of the conductor surface in contact with the cryogenic refrigerant Is less, and the stability of superconducting properties is reduced.

The present invention has been made on the basis of such a background, measures are taken to prevent movement of the superconducting conductor due to electromagnetic force, cooling of the superconducting conductor is good, and high electric insulation performance is provided. The purpose is to provide a superconducting busbar.

[0006]

DISCLOSURE OF THE INVENTION As a result of studies in view of the above, the present invention has developed a superconducting bus bar that solves these problems. A cryogenic refrigerant is circulated inside a hollow tube containing a superconducting conductor. And, a spacer is arranged between the superconducting conductor and the inner surface of the hollow tube, and a plurality of cores having an electric insulating layer on the outer periphery of the hollow tube and a ground electrode layer further outside thereof are bound together. To do.

In this superconducting bus bar, it is effective to use a conductive or semiconductive spacer or to bind a plurality of cores with a conductive or electrically insulating tape material or wire material. Further at this time, as a spacer, it is more effective to spirally wrap it around a superconducting conductor along with a semiconductive fiber containing conductive carbon or a metal wire having good electric conductivity. It is also effective to use a braided wire having a large air permeability as the binding material for the plurality of cores, or to wind and bind the tape in a spiral shape along the longitudinal direction of the core using a tape material made of glass fiber or plastic. .

[0008]

According to the present invention described above, the following actions can be taken with respect to countermeasures against electromagnetic force, cooling stability of the superconducting conductor, and electric insulation performance.

Countermeasures against electromagnetic force By providing a binding material for binding a plurality of cores as a countermeasure against electromagnetic force and further providing a spacer between the superconducting conductor and the inner surface of the refrigerant hollow tube, the movement of the superconducting conductor due to electromagnetic force is performed. Can be stopped to prevent the quench phenomenon.

Cooling Stability of Superconducting Conductor The surface area of liquid helium in contact with the surface of the superconducting conductor is increased, the cooling stability of the superconducting conductor is improved, and even if the superconducting conductor moves for some reason and frictional heat is generated. Since the heat can be quickly radiated to the refrigerant, the quenching of the superconducting conductor becomes more difficult to occur.

Electrical Insulation Performance Since the electrical insulation layer is arranged around the hollow tube, the dielectric breakdown path in the creeping direction between the cores of these tubes is structurally eliminated, and the electrical insulation performance is improved.

[0012]

EXAMPLES The present invention will now be described with reference to examples.

(Embodiment 1) As shown in FIG. 1, a cryogenic refrigerant pipe (copper) having an outer diameter of 35 mm and containing an aluminum-stabilized niobium titanium superconducting conductor (1) (2) having a designed maximum current capacity of 40 kA and a designed rated current of 20 kA. A core having a structure in which a 1.2 mm-thick electrical insulating layer (3) was formed on the outer periphery of the pipe (4) and a 0.6 mm-thick ground electrode layer (7) was provided on the outer side thereof was produced. Between the superconducting conductors (1) and (2) and the inner surface of the copper pipe (4), a reinforcing fiber-plastic fiber (6) (semiconductive) containing conductive carbon is spirally wound. The superconducting conductor is firmly fixed in the copper pipe (4). The electrical insulation layer (3) is extruded ethylene propylene rubber (EPR).
The ground electrode layer (7) has a width of 30 mm and a thickness of 100 μ.
It has a structure in which a copper tape of m is wound three times with 1/2 wrap. Then, these two cores were bound with a glass tape (8). This glass tape is 40mm wide and 300μm thick
It was wound spirally at intervals. Note that (5) in the figure indicates a cryogenic refrigerant.

When the characteristics of this superconducting bus bar of the present invention were tested, the critical current in liquid helium in a boiling state at atmospheric pressure was the above rated current of 20 kA or more. And rated current 20kA
The electricity was turned on and off repeatedly 1000 times, but no phenomenon such as quenching due to movement of the superconducting conductor due to electromagnetic force was observed.

The reason why good stability is obtained is as follows.
The fact that the cores are bound together as a countermeasure against electromagnetic force, that there is a spacer between the superconducting conductor and the inner surface of the refrigerant hollow tube, and at the same time that the surface area of liquid helium in contact with the superconducting conductor surface is sufficiently large, is acting it is conceivable that.

DC voltages of +10 kV and -10 kV were applied to the respective superconducting conductors in the two cores at the liquid helium temperature for 5 consecutive days, but no electric breakdown occurred. It is considered that such a high electric insulation performance is due to the fact that the electric insulation layer is arranged around the circular pipe and the dielectric breakdown path in the creeping direction is structurally eliminated.

(Embodiment 2) Next, an example in which the present invention is applied to a three-phase AC conductor will be described. This three-phase AC conductor (9)
(9) With respect to (9), cores having the same structure as in Example 1 are arranged as shown in FIG. 2, and the outer circumference is spirally wound with glass tape (8) at three spiral intervals to form three cores. A superconducting bus bar was prepared by bundling. The characteristics of this superconducting busbar were investigated in the same manner as in Example 1, but as in Example 1, no phenomenon such as quenching due to movement of the superconducting conductor occurred.

[0018]

As described above, in the superconducting bus bar of the present invention, the movement of the superconducting conductor due to the electromagnetic force is prevented, and at the same time, the cooling state of the superconducting conductor is good and the electric insulation is higher than the conventional one. It has the effect that it also has performance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of the present invention.

FIG. 2 is a sectional view showing another example of the present invention.

FIG. 3 is a perspective view of a main part of a conventional superconducting bus bar.

[Explanation of symbols]

 1 Forward Conductor 2 Reverse Conductor 3 Electrical Insulation Layer 4 Hollow Tube 5 Cryogenic Refrigerant 6 Spacer 7 Grounding Electrode Layer 8 Glass Tape 9 3 Phase AC Conductor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naotaka Ichiyanagi 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Yoshio Furuto 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Takeshi Ito Higashishin-cho, Higashi-ku, Nagoya, Aichi Chubu Electric Power Co., Inc. (72) Inventor Toshiaki Nagafusa Higashi-ku, Higashi-ku, Nagoya, Aichi Chubu Electric Power Co. In-house (72) Inventor Hirokazu Misawa, Chubu Electric Power Co., Inc.

Claims (7)

[Claims] 1. A cryogenic refrigerant is circulated inside a hollow tube containing a superconducting conductor, a spacer is arranged between the superconducting conductor and the inner surface of the hollow tube, and an electrical insulating layer is provided on the outer periphery of the hollow tube. A superconducting bus bar, characterized in that a plurality of cores each having a ground electrode layer provided on the outside thereof are bound together. 2. The superconducting busbar according to claim 1, wherein the spacer is conductive or semiconductive. 3. The superconducting busbar according to claim 1, wherein the spacer is formed by winding a semiconductive fiber containing conductive carbon around the superconducting conductor in a spiral shape. 4. The superconducting bus bar according to claim 1 or 2, wherein the spacer is formed by spirally winding a metal wire rod having a good electric conductivity around the superconducting conductor. 5. The superconducting bus bar according to claim 1, wherein a plurality of cores are bound by a conductive or electrically insulating tape material or wire material. 6. The superconducting bus bar according to claim 5, wherein a plurality of cores are wound together in a spiral shape along a longitudinal direction of the cores with a wire rod made of a braided wire having high air permeability to bind the cores. 7. A plurality of cores are bound by spirally winding them with a tape material made of glass fiber or plastic along the longitudinal direction of the cores at intervals.
Superconducting bus bar described in.