JPH0836924A - Superconducting ac strand - Google Patents

Abstract

PURPOSE:To provide a superconducting strand for AC which is unlikely to generate quenching by hindering a current from flowing in core wire. CONSTITUTION:Each superconducting element wire 1 is structured so that a number of filaments of superconducting member of Nb-Ti 3 are embedded in a matrix of Cu-Ni 2. A plurality of such element wires 1 are stranded a core wire 4 of high strength insulating fiber to form a primary strand 5, and a plurality of such primary strands are stranded around a core wire 4' of the same material to form a secondary strand 6. Repeating this cycle accomplishes a strand of higher order structuer, which is used as a superconducting strand for AC.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC superconducting stranded wire used in AC devices such as superconducting fault current limiters and superconducting transformers.

[0002]

2. Description of the Related Art A conventional superconducting stranded wire for alternating current is disclosed in Japanese Patent Laid-Open No. 5-198.
As shown in Japanese Patent No. 223, the core wire is made of Cu-Ni or stainless steel, and a plurality of Nb-Ti superconducting wires made of Cu-Ni as a matrix material are twisted around the core wire to form a primary twisted wire. Then, a plurality of primary twisted wires are twisted around the core wire to form a secondary twisted wire, and a tertiary twisted alternating current superconducting twisted wire is formed in the same manner. Cu-Ni or stainless steel having a relatively high resistance value is used for the core wire to minimize the eddy current loss and the coupling loss between the superconducting element wire and the core wire. However, the heat generated by these losses has a drawback that it conducts to the superconducting element wire to quench the superconducting stranded wire.

Further, as disclosed in Japanese Utility Model Laid-Open No. 62-55826, a Cu-Ni alloy wire is used as a core wire of a superconducting stranded wire with a heat resistant insulating coating, and a multi-core structure is formed around the core wire. There is an example in which a plurality of superconducting element wires are twisted together to form an AC superconducting twisted wire. However, in this example, since the core wire is insulated, a superconducting element wire-coupling loss between core wires does not occur, but since an electrically conductive Cu-Ni alloy wire of the core wire is used, an induction current due to an alternating current flows through the core wire, There is a drawback in that heat is generated due to eddy current loss to quench the AC superconducting stranded wire.

Further, Japanese Patent Laid-Open No. 5-198223 and Shokai Sho 62
The superconducting stranded wire for AC in −55826 is made as thin as possible to reduce eddy current loss. Therefore, in an AC device such as a superconducting fault current limiter and a superconducting transformer, a large current flows, so that the coil conductor is easily deformed by the electromagnetic force generated, and the super electric wire may be quenched by the heat at the time of deformation. Also, when a three-phase short circuit occurs in the power system, more than twice the normal current flows in superconducting transformers, etc.
It is also possible that the superconducting wire breaks due to the electromagnetic force generated.

[0005]

The object of the present invention is to eliminate the quench of the superconducting wire due to the AC loss generated in the core wire as described above, and to cause the superconducting wire to be plastically deformed by the electromagnetic force generated by the AC equipment. To make it difficult for the superconducting wire to quench, and to prevent breakage of the superconducting wire due to the electromagnetic force generated by the superconducting coil when a much larger current than usual flows to AC equipment due to a short-circuit in the power system, etc. To do.

[0006]

In order to achieve the above object, in the present invention, high-strength electrically insulating fibers and semiconductive fibers are used for the core wires from the primary to the final twisted wire of a superconducting twisted wire for alternating current. Further, a thread using these fibers is impregnated with a synthetic resin such as an epoxy resin and used as an FRP core wire.

In the first aspect, the high-strength electrically insulating fiber and the semi-conductive fiber are used as a single thick fiber, and a plurality of thin fibers are twisted together.

In claim 2, high-strength polyethylene fibers, aramid fibers, glass fibers and alumina fibers are used as the high-strength electrically insulating fibers, and carbon fibers are used as the high-strength semiconductive fibers, and these fibers are used alone or Used in combination.

In a third aspect, the yarn using the fiber of the second aspect is impregnated with one of epoxy resin, polyester resin and polyurethane resin to be used as an FRP core wire.

According to a fourth aspect of the present invention, the superconducting twisted wire for alternating current using the core wire of the first to third aspects is used as a superconducting coil of a superconducting fault current limiter, a superconducting transformer, a superconducting generator, an accelerator and a pulse generator, and a fusion device. Used for center solenoid coil and poloidal coil, AC superconducting power cable.

[0011]

[Function] As described above, by using the high-strength electrically insulating fiber of the core wire of the superconducting twisted wire for AC used in the superconducting AC equipment, no current flows through the core wire, and the carbon fiber is a semi-conductive fiber. Even when using, the current hardly flows, and eddy current loss and superconducting wire-core wire coupling loss do not occur. Therefore, AC equipment such as a superconducting fault current limiter and a superconducting transformer using the AC superconducting twisted wire of the present invention, the energizing current can be increased more than when using the conventional AC superconducting twisted wire and quenching is less likely to occur. can do.

Further, when a normal alternating current flows through the superconducting coil, a radial outward outward seeding electromagnetic force is generated, so that tensile stress is applied to the superconducting wire, so that the superconducting wire is prone to plastic deformation. For this reason, when the conventional superconducting stranded wire is used, plastic deformation is likely to occur to cause quenching, whereas in the AC superconducting stranded wire using the high-strength core wire of the present invention, the tensile strength of the core wire is 4 times that of the conventional core wire. Since it is as large as ~ 5.5 times, the tensile strength and
The 2% proof stress is about twice as large, and plastic deformation hardly occurs.

Further, when a three-phase short circuit or the like occurs in the power system, a current of more than twice the rated current flows in the AC device, so that the superconducting wire may be broken. However, the superconducting stranded wire of the present invention has tensile strength. Since it is large as described above, breakage is unlikely to occur.

According to the second aspect, the high-strength electrically insulating fibers and the semiconductive fibers are used alone or in combination. However, fibers such as high-strength polyethylene fibers exhibiting negative heat shrinkage at cryogenic temperatures are wound. Since it has the effect of reducing the tension during drawing at extremely low temperatures, it is possible to make the heat shrinkage positive by using it in combination with an external fiber that exhibits positive properties, and at the same time, by averaging the tensile strength, The selection range is expanded.

According to a third aspect of the present invention, the FRP core wire is formed by impregnating the yarn using the fiber of the second embodiment with a synthetic resin such as an epoxy resin, so that the steel wire and the strength of the core wire are increased, and the superconducting stranded wire is plastically deformed. Also, breakage can be made less likely to occur.

[0016]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2 and Tables 1 and 2.

FIG. 1 is a first embodiment of the present invention and shows a cross-sectional structure of a superconducting twisted wire for alternating current of a secondary twisted wire using a high-strength polyethylene fiber as a core wire. The superconducting wire 1 constituting the AC superconducting stranded wire has a wire diameter of 0.25 mmφ, and the superconducting material N is contained in the normal-conducting matrix material Cu-Ni2.
A large number of filaments of b-Ti3 are embedded. Six superconducting wires 1 are twisted around a core wire 4 of 0.25 mmφ high strength polyethylene fiber to form a primary stranded wire 5 having an outer diameter of 0.75 mm. This primary stranded wire 5 is a secondary stranded wire having an outer diameter of 2.25 mm by twisting six primary stranded wires 5 around a core wire 4'which is a 0.75 mmφ high-strength polyethylene fiber. Configure line 6.

Element 1 shows the specifications of the AC superconducting twisted wire of the present invention and the conventional AC superconducting twisted wire.

[0019]

[Table 1]

The superconducting element wire is the same in the present invention and the prior art, and the outer diameters of the primary stranded wire and the secondary stranded wire are also the same. The tensile strength of the secondary stranded wire is twice that of the conventional one.

A superconducting coil using the AC superconducting twisted wire of the present invention and the conventional AC superconducting wire was manufactured, and the quench current due to AC energization was measured. Table 2 shows the specifications of the superconducting coil for AC and the quench current.

[0022]

[Table 2]

While the quench current of the conventional superconducting coil using the AC superconducting twisted wire is 420 A with a load factor of 30%, the quench current of the superconducting coil using the AC superconducting twisted wire of the present invention is the load factor. It was 850A of 60%.
A superconducting coil using a conventional AC superconducting twisted wire is considered to be affected by the eddy current loss of the core wire used for the twisted wire and the coupling loss between the superconducting element wire and the core wire, and thus the AC superconducting twisted wire of the present invention is used. It is considered that the superconducting coil had no effect. Therefore, even if the aramid fiber, the glass fiber and the alumina fiber shown in Table 3 are used as the core wire of the superconducting stranded wire for AC and the carbon fiber is used as the high strength semi-conductive fiber, the superconducting performance is The same effect as the first embodiment of the invention can be obtained.

[0024]

[Table 3]

The same effects as those of the first embodiment of the present invention can be obtained by using these fibers alone or in combination. The second embodiment of the present invention is shown in FIG. In this example, as a core wire of a superconducting twisted wire for alternating current, a thread in which a high-strength polyethylene fiber 7 and an aramid fiber 8 were combined was formed, and an FRP core wire 10 in which this thread was impregnated with an epoxy resin 9 was prepared and used. The alternating-current superconducting stranded wire of the present invention using the core wire as described above for the primary stranded wire and the secondary stranded wire has the effects of increasing rigidity and having a positive thermal contraction rate at cryogenic temperatures.
The superconducting coil for AC having the same specifications as the first embodiment of the present invention using the superconducting twisted wire for AC has the same superconducting performance as that of the first embodiment of the present invention. Therefore, the high-strength electrically insulating fiber and semiconductive fiber described in claim 3 are combined, and the FRP core wire impregnated with one kind of the synthetic resin described in claim 3 is superconducting twisted for AC. It is clear that the same effect as that of the first embodiment of the present invention can be obtained by using it as the core wire of the wire.

In the first and second embodiments of the present invention, the superconducting performance is sought with a small superconducting coil. The superconducting twisted wire for AC of the present invention is used as a superconducting fault current limiter, a superconducting transformer, a superconducting generator, an accelerator. Also, when used in a superconducting coil of a pulse generator, a superconducting power cable for alternating current, a center solenoid coil for fusion, and a poloidal coil, the same effect as that of the embodiment of the present invention can be obtained, and a large electromagnetic force generated by the superconducting coil can be obtained. Even if added to the conductor, the conductor does not easily undergo plastic deformation and quenching does not occur easily. Further, it is difficult for the conductor of the superconducting coil to break when a short circuit occurs in the power system.

[0027]

According to the present invention, no current flows in the core wire, and heat is not generated due to the eddy current loss and the superconducting element wire-core wire coupling loss that have occurred in the core wire of the conventional AC superconducting stranded wire. The quench current becomes large in the superconducting coil using this AC superconducting stranded wire. Further, the rigidity and the tensile strength are increased, and in the superconducting coil using the superconducting twisted wire for alternating current, the plastic deformation of the conductor hardly occurs and the quenching hardly occurs. Further, even if a short circuit or the like occurs in the power system in which the AC device is operating and a large current exceeding the rated current flows in the AC device, the AC superconducting twisted wire is not broken by the electromagnetic force.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an AC superconducting stranded wire showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an embodiment of a core wire used in the AC superconducting stranded wire of the present invention.

[Explanation of symbols]

1 ... Superconducting element wire, 2 ... Matrix material Cu-Ni, 3 ...
Superconducting material Nb-Ti, 4, 4 '... High-strength polyethylene fiber core wire, 5 ... Primary twisted wire, 6 ... Secondary twisted wire.

Claims (4)

[Claims] 1. A primary stranded wire is formed by twisting a plurality of superconducting element wires, in which a large number of superconducting filaments are embedded in a normal conducting metal, around a core wire, and forming a plurality of primary stranded wires around the core wire. Twisted to form a secondary stranded wire, and in the same manner, the tertiary to n
A superconducting twisted wire for alternating current, characterized in that, in the superconducting twisted wire for alternating current formed with the following twisted wire, high-strength electrically insulating fiber and semiconductive fiber are used for the core wire. 2. The high-strength polyethylene fiber, aramid fiber, glass fiber and alumina fiber are used as the electrically insulating fibers used in the core wire of the superconducting twisted wire for alternating current according to claim 1, and carbon fiber is used as the semi-conductive fiber. A superconducting twisted wire for alternating current using these fibers alone or in combination. 3. The yarn according to claim 1 or 2, wherein, as the core wire used for the AC superconducting stranded wire, a thread using a large number of the electrically insulating fibers and the semiconductive fibers alone or in combination is formed, and the epoxy is used as the thread. A superconducting twisted wire for alternating current using an FRP core wire impregnated with one kind of resin, polyester resin and polyurethane resin. 4. The superconducting fault current limiter, the superconducting transformer, the superconducting generator, the AC superconducting power cable, the fusion device center solenoid coil and the poloidal coil according to claim 1, 2, or 3. , Superconducting coils for accelerators and pulse generators.