JP2530065B2 - Superconducting device current lead - Google Patents

Description

Detailed Description of the Invention

 [Object of the Invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current lead of a superconducting device.

[0002]

2. Description of the Related Art A conventional current lead will be described with reference to FIGS.

FIG. 4 shows a structure of a typical conventional superconducting magnet, in which a current is supplied to a superconducting coil 1 through a current lead body 2 and a connecting lead 3. Superconducting coil 1
Is heat-insulated and stored in the cryogenic container 4. Cryogenic container 4
The internal atmosphere and the external atmosphere are shielded by a top flange 5 mechanically fixed to the cryogenic container 4, and the current lead body 2 is penetratingly held by the top flange 5.
Other pipes and the like (not shown) are attached. Liquid helium 6 is stored in the cryogenic container 4, and by immersing the superconducting coil 1, the superconducting coil 1 is cooled to a superconducting state (about −269 ° C.).

As shown in FIG. 5, the portion of the current lead body 2 is an insulating flange 7 in the room temperature region, which is a top flange 5.
Cryogenic container 4 that maintains the withstand voltage insulation of the current lead body 2 and
The inside and outside atmospheres are hermetically sealed by the gasket 8. The current lead body 2 generates heat due to resistance loss due to energization, and this amount of heat penetrates into the liquid helium 6 through the current lead body 2 and the connecting lead 3 to increase the evaporation amount of the liquid helium 6. Therefore, in order to reduce the amount of heat generated in the current lead body 2 and the amount of heat transferred to the liquid helium 6 due to conduction, a cooling flow path (not shown) is generally provided inside the current lead body 2 to provide liquid helium. A method of guiding the vaporized gas 9 of 6 to the cooling flow path to cool the current lead body 2 is adopted. The current lead body 2 is provided with a terminal plate 10 for connecting to an external power source on the room temperature side.

[0005]

The evaporative gas 9 of the liquid helium 6 due to the resistance loss generated in the current lead body 2 due to the energization of the coil is discharged to the room temperature side through the cooling flow path of the current lead body 2. The heat is not completely exchanged in the current lead body 2 and the low temperature evaporative gas is discharged. Therefore, the temperature of the terminal plate 10, the flange 11 and the members in the vicinity thereof becomes low, and the moisture in the atmosphere becomes frost and adheres to the surface of these. Then, the surface of the frost adhered during the operation cycle of the superconducting coil 1 is melted to cover the surface of the insulating flange 7 with water, and the withstand voltage between the flange 11 of the current lead body 2 and the top flange 5 is lowered.

Since a relatively small DC superconducting magnet in the related art generates a low voltage, there are many, and even if the insulating flange 7 is wet with water, there is no problem because the dielectric strength is secured, but in recent years, the superconducting coil has been Applications are expanded, and for example, in power storage systems and superconducting transformers, the generated voltage power is as high as several KV, and with frost and moisture adhering to it, it is not possible to ensure dielectric strength and normal operation is impossible. Become. Further, the state where the high voltage portion is exposed in the upper space of the top flange 5 may cause an electric shock accident if a person accidentally approaches. Therefore, an object of the present invention is to provide a current lead which is free from frost on the room temperature side of the current lead and which is safe even when a person approaches it. [Constitution of Invention]

[0007]

In order to achieve the above-mentioned object, the present invention has a structure in which the room temperature side of the current lead body is covered with an insulating case, and the inside of this case is evacuated or a dry gas is made to flow.

[0008]

In the current lead having such a structure, the room temperature side portion is covered with an insulating case, the inside is replaced with a dry gas having a good insulating property such as nitrogen gas, and the current lead terminal plate is made to flow. It is possible to prevent frost from being generated and attached to the surface of the flange, etc. Further, by flowing the dry gas, it is possible to prevent the terminal board and the like from being excessively cooled. In addition, it is safe for humans to approach by mistake.

[0009]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a current lead according to a first embodiment of the present invention. The same parts as those in FIGS. 4 and 5 are designated by the same reference numerals.
I will describe the points that are different from.

In this embodiment, the tubular portion of the current lead body 2 is covered with an insulating tube 12 integrated with the insulating flange 7, and the tubular portion and the insulating tube 12 are hermetically sealed with epoxy resin or the like. The current lead body 2 is attached to the top flange 5 by using the insulating flange 7, and the gasket is inserted between the flanges.
The inner space atmosphere and the shielding seal. Further, an insulating case 13 that covers the whole of the current lead body 2 at room temperature is provided on the top flange 5, and the connection portion is sealed and connected.

A pipe 14 for discharging the vaporized gas 9 is connected to the upper portion of the current lead body 2 and has a structure which penetrates the wall surface of the insulating case 13 and guides it to the outside. Since the through portion is airtightly sealed, as shown in FIG. 2, the gasket 15, packing retainer 16,
Consists of a cap nut 17. Power supply cable 18 that connects to the power supply
Is connected to the terminal board 10 by a flexible conductor 19. The airtight seal of the cable 18 is performed by the sleeve 20, the cap nut 21, the gasket 22, and the sealing material 23. The insulating case 13 is provided with a port 24 for introducing and discharging dry gas.

Next, the operation will be described. The evaporative gas 9 passes through the internal cooling flow path of the current lead body 2, and the upper discharge pipe.
It is discharged from 14 to the outside of the insulating case 13. Insulation case 13
The internal space is replaced by introducing and discharging a dry gas having a good insulating property from the port 24 inside.

Therefore, even if the room temperature side member is cooled to 0 ° C. or less, since it is in the dry gas atmosphere, frost is not generated and adhered. Further, since the dry gas is forced to flow, the room temperature member can be prevented from being heated and excessively cooled. Besides, in the case of a current lead to which a high voltage is applied, even if a person accidentally approaches the current lead, the current lead is not directly touched, so that an electric shock accident can be prevented. (Embodiment 2) In the second embodiment, as shown in FIG. 3, an insulating case 13 is provided with a bottom plate 25, and the current lead body 2 is attached thereto by an insulating flange 7. Even with such a configuration, the same operation as that of the first embodiment can be obtained. (Embodiment 3) The third embodiment is a port in FIGS.
The vacuum is evacuated from one or more places of 24 to create a vacuum atmosphere in the insulating case. Even with such a configuration, the same operation as that of the first embodiment can be obtained.

[0015]

As described above, according to the present invention, it is possible to provide a safe current lead of a superconducting device which can maintain withstand voltage insulation without frost adhering to the room temperature side of the current lead.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is an enlarged view showing an airtight seal portion in the above embodiment.

FIG. 3 is a sectional view showing a second embodiment.

FIG. 4 is a vertical cross-sectional view showing the structure of a conventional superconducting magnet.

FIG. 5 is a vertical cross-sectional view showing the configuration of a conventional current lead.

[Explanation of symbols]

1 ... Superconducting coil 2 ... Current lead body 3 ... Connection lead 4 ... Cryogenic container 5 ... Top flange 6 ... Liquid helium 7 ... Insulation flange 8 ... Gasket 9 ... Evaporated gas 10 ... Terminal plate 11 ... Flange 12 ... Insulation tube 13 … Insulation case 14… Discharge pipe 15, 22… Gasket 16… Packing retainer 17, 21… Cap nut 18… Cable 19… Flexible conductor 20… Sleeve 23… Sealing material 24… Port 25… Bottom plate

Claims (1)

(57) [Claims] 1. A lead outer tube having a room temperature side terminal at one end and a low temperature side terminal at the other end, and a lead body which is installed in the hollow portion of the lead outer tube and whose ends are conductively joined to both terminals. Which is inserted in a cryogenic container in an airtight manner to supply a current to a superconducting device and is cooled by vaporized gas of a refrigerant liquid passing through the hollow portion, and which is provided with an insulating case covering a normal temperature side of the lead body, A current lead for a superconducting device, characterized in that the inside of the insulating case is evacuated or a dry gas is made to flow.