JPH07161519A - Superconducting unit - Google Patents

Abstract

PURPOSE:To achieve high reiability by enhancing the insulation performance at the joint of a current lead and a superconducting coil. CONSTITUTION:A superconducting coil immersed into liquid refrigerant filled in a vessel is coupled with a current lead 21 having a channel for passing gasified refrigerant through the interior of the supeconducting coil, and the current lead is fixed through a subflange 25 to a fixed flange 27 on the vessel side. In such superconducting unit, the current lead 21 is tapered at the part corresponding to the fixed flange 27 and a tapered fixing part 26 fitting to the current lead 21 is provided at the open end of the subflange 25. The current lead 21 is inserted into the opening of the subflange 25 and fixed in place while being held on the fixing part 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superconducting device having an immersion cooling type superconducting coil, and more particularly to a superconducting device in which a current lead for energizing the superconducting coil is attached to a fixed flange on the container side.

[0002]

2. Description of the Related Art In immersion cooling type superconducting coils, a method is used in which a current lead for energizing the coil is attached to a fixed flange on the container side, and the current lead is generally cooled by evaporated helium gas. Has been done.

Usually, the flow path of the refrigerant is provided inside the current lead, and the refrigerant is introduced from the lower end portion of the current lead and discharged from the upper end portion thereof. Further, since the connection with the superconducting coil is made at the lower end portion of the current lead, the lower end portion of the current lead is provided with an inlet for the gasified refrigerant and a connecting portion with the superconducting coil. In this case, the lower end of the current lead is positioned above the liquid surface of the liquid helium, that is, in the gas space, so that the gasified refrigerant can be introduced.

By the way, the insulating performance of gasified helium is generally much lower than that of air or the like. Therefore, when the superconducting coil cooled by liquid helium is energized with an alternating current and a high voltage is applied, if the vaporized helium gas is filled around the current leads, the insulating performance of the helium gas is low, Partial discharge may occur in the current lead. Especially in the vicinity of the flange where the temperature of the helium gas is relatively high, the insulation performance may be significantly deteriorated.

Therefore, as a measure against such a problem, for example, as shown in Japanese Patent Application No. 4-3008889 filed previously, a method of filling the flange of the current lead with a gas having a high insulation performance, etc. This prevents the insulation performance from deteriorating.

FIG. 6 shows an example of the structure of a superconducting device which takes such measures. As shown in FIG. 6, the current lead 1 in which the outer periphery of the conductor 2 having the refrigerant flow path 2a is covered with the insulator 3 except the upper end and the lower end is attached to the fixed flange 4 on the container side. The sub-flange 6 is fixed to the outer periphery of the cylindrical gas filling portion 5 attached to the upper part of the insulating coating portion by a screwing method, and the sub-flange 6 is attached to the fixing flange 4.

Further, a gas chamber 7 for filling a gas having a high insulation performance such as nitrogen gas is formed inside the gas filling portion 5, and a rubber balloon 8 is connected to the gas chamber 7 and a rubber balloon 8 is formed therein. Is mounted above the to adjust the gas pressure.

Further, a connecting portion 9 for connecting an AC power source is provided above the conductor 2, and a connecting conductor for energizing a superconducting coil (not shown) immersed in liquid helium 10 is provided under the conductor 2. 11 is connected.

[0009]

The superconducting device provided with the current lead having such a structure has the following problems. First, since the sub-flange 6 for fixing the current lead 1 to the fixing flange 4 is attached to the outer periphery of the gas filling portion 5 by a screwing method, the outer peripheral surface of the gas filling portion 5 and the sub-flange 6 are joined together. It is inevitable that there will be a gap between the screws.

For this reason, when helium gas enters the gap, corona discharge or the like may occur in the helium gas space, which may lead to deterioration of insulation performance, which is problematic in terms of long-term reliability. Further, although the screw portion is also filled with an epoxy resin or the like, since it is cooled to a low temperature, cracks and peeling occur due to heat history and the like, and there is a difficulty in long-term reliability.

Further, by filling the gas chamber in the gas filling portion 5 attached to the upper portion of the insulating coating portion of the current lead 1 with a gas having high insulating performance, the insulating performance is enhanced, and the conductor 2 of the current lead 1 The conductor 2 is cooled by flowing low-temperature helium gas evaporated from the coolant inlet port 2b into the coolant channel 2a.

Therefore, since the temperature of the surface of the fixed flange 4 is lower than the room temperature, dew condensation occurs on the surface of the fixed flange 4, and the connection portion 9 is also cooled, so that dew condensation occurs. . Therefore, there is a problem that the insulation performance is deteriorated between the flange 4 and the connecting portion 9.

The present invention has been made to solve the above problems, and provides a superconducting device capable of improving the insulation performance at the connection between the current lead and the superconducting coil and obtaining high reliability. The purpose is to do.

[0014]

In order to achieve the above object, the present invention constitutes a superconducting device by the following means. (1) A superconducting coil provided by immersing it in a refrigerant liquid contained in a container is connected to a current lead having a refrigerant passage for circulating a gasified refrigerant therein, and the current lead is a sub-flange. In the superconducting device adapted to be attached to the fixed flange on the container side via, the portion corresponding to the fixed flange of the current lead is tapered, and the opening end portion of the sub-flange matches the tapered surface of the current lead. A mounting portion having a tapered surface is provided, the current lead is inserted into the opening of the sub-flange, and the mounting portion is held and mounted. (2) In the superconducting device having the above configuration (1), a screw portion is provided on the atmosphere side of the taper surface of the mounting portion of the sub-flange,
The screw leads fix the current leads. (3) In the superconducting device having the configuration of (1) above, a screw portion is provided on the atmosphere side of the tapered surface of the mounting portion of the sub-flange,
A fixing ring is screwed onto this screw portion to fix the current lead and the sub-flange. (4) A current lead having a refrigerant flow path for circulating a gasified refrigerant therein is connected to a superconducting coil provided by being immersed in a refrigerant liquid contained in a container, and this current lead is a sub-flange. In the superconducting device adapted to be attached to the fixed flange on the container side via, the connection part for connecting the current lead to the external power cable is sized to exist in the insulating gas atmosphere, and the bottom part is located below the fixed flange surface. The current lead is provided with a gas-filled portion formed in this manner.

[0015]

In the superconducting device having the above-mentioned construction (1), the tapered surface formed on the current lead and the tapered surface formed on the mounting portion at the opening end of the sub-flange for mounting on the fixed flange on the container side. Since the current lead is held in close contact with and, there is no gap between the denry lead and the sub-flange, and the vaporized refrigerant does not enter between the current lead and the sub-flange, and the insulation performance is improved. Can be prevented from deteriorating. Further, the current leads are held in a state of being in close contact with each other by the taper provided in the mounting portion, so that they can be easily attached to and detached from the sub-flange.

In the superconducting device having the structure as described in (2) above, in addition to the function of (1) above, the current lead and the sub-flange are screwed by the screw portion, so that the sealability at the mounting portion is improved. Is increased, reliability in preventing deterioration of insulation performance due to invasion of gasified refrigerant is improved, and the current lead can be securely attached to the sub-flange by screwing.

In the superconducting device having the structure as described in (3) above, in addition to the function of (1) above, the current lead is pushed down by the mounting ring, so that the sealing property at the mounting portion increases and gasification occurs. The reliability in preventing the deterioration of the insulation performance due to the invasion of the refrigerant is improved, and the current lead can be securely attached to the sub-flange by screwing.

In the superconducting device having the structure (4), the connection between the current lead and the power cable is provided in the gas filling portion filled with the insulating gas, and the bottom portion of the gas filling portion is provided. Is located below the mounting surface of the fixing flange on the container side, it is possible to prevent dew condensation due to cooling between the connecting portion of the current cable and the current lead and the fixing flange, thus preventing deterioration of insulation performance. Can be prevented.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a structure of a mounting portion of a current lead according to a first embodiment of the present invention. In FIG. 1, 2
Reference numeral 1 denotes a current lead in which the outer periphery of the conductor 22 having the refrigerant flow path 22a inside is covered with an insulator 23 except the upper end portion and the lower end portion, and an annular gas filling portion 24 is provided above the insulating coating portion of the current lead 21. Are provided integrally.

The annular filling portion 24 has a gas chamber 2 inside.
4a, and the outer peripheral side surface is tapered. Further, reference numeral 25 is a sub-flange for attaching the current lead 21 to the fixed flange 27 on the container side, and a tapered surface matching the tapered surface of the outer peripheral side of the gas filling portion 24 is formed at the opening end of the sub-flange 25. The attached mounting portion 26 is provided.

Further, with the sub-flange 25 attached to the fixed flange 27 by the attachment screw 28, the gas filling portion 24 of the current lead 21 is inserted into the opening of the sub-flange 25 and held by the attachment portion 26, and the current lead is held. 21 is attached to the fixing flange 27.

A gas supply pipe 29 for supplying a gas having a high insulating performance such as nitrogen gas is connected to the gas filling portion 24 of the current lead 21 so as to communicate with the gas chamber 24a. The gas exhaust pipe 30 is connected to the target position in communication with the gas chamber 24a.

A connecting portion 31 for connecting to an AC power source is attached to the upper end of the conductor 22 of the current lead 21, and a donut-shaped electrostatic shield 32 is attached to the lower end of the conductor 22. A connection conductor 34 for energizing a superconducting coil (not shown) immersed in liquid helium is connected to the connected electrode 33.

Further, for the mounting portion 26 of the current lead 21, the gas filling portion 24 is filled with a gas having high insulation performance,
Further, the low-temperature helium gas evaporated from the refrigerant introduction port 22b is made to flow into the refrigerant passage 22a in the conductor 22 and is discharged from the refrigerant discharge port 22d.

As described above, in the first embodiment, the outer peripheral portion of the annular gas filling portion 24 formed on the insulating coating portion of the conductor 22 of the current lead 21 is tapered, and the sub-flange 25 is formed. Since the mounting portion 26 having a tapered surface that matches the tapered surface of the gas filling portion 24 is provided in the opening portion and the gas filling portion 24 is inserted into the opening hole of the sub-flange 25 and held by the mounting portion 26. Therefore, no gap is formed between the gas filling portion 24 and the sub-flange 25, so that the helium gas having low insulation performance can be prevented from entering the mounting portion 26. As a result, the insulation performance in this portion does not deteriorate.

Since the current lead 21 is attached only by inserting the gas filling portion 24 along the tapered surface of the attachment portion 26 of the sub-flange 25, there is an advantage that the current lead 24 can be easily attached and detached.

FIG. 2 is a sectional view showing the structure of the mounting portion of the current lead in the second embodiment of the present invention. The same parts as those in FIG. I will describe the points.

In the second embodiment, as shown in FIG. 2, the opening portion of the sub-flange 25 is provided with a mounting portion 26 having a tapered surface that matches the tapered surface of the outer peripheral side of the gas filling portion 24.
A fixing member 26b having a screw portion 26a is provided on the inside of the mounting portion 26, and the screw portion 26a of the fixing member 26b is screwed into the screw portion formed on the vertical surface of the gas filling portion 24.

Therefore, with such a structure, the gas filling portion 24 of the current lead 21 is provided in the opening of the sub-flange 25.
Is inserted into the mounting portion 26 and held by the mounting portion 26, and the gas filling portion 24 is screwed by the screw portion 26a of the fixing member 26b, whereby the sealing performance of the mounting portion 26 is increased and the deterioration of the insulation performance due to the invasion of helium gas is prevented. Reliability is improved. Further, the current lead 21 can be securely attached to the sub-flange 25 by screwing.

FIG. 3 is a cross-sectional view showing the structure of the mounting portion of the current lead in the third embodiment of the present invention. The same parts as those in FIG. I will describe the points.

In the third embodiment, as shown in FIG. 3, the mounting portion 26 having a tapered surface provided at the opening end of the sub-flange 25 is in contact with the vertical surface of the gas filling portion 24 and the outer peripheral surface is screwed. A fixing member 26b having a groove is provided, and a mounting ring 35 that is screwed with the fixing member 26b is screwed into the fixing member 26b.

Therefore, with such a structure, the gas filling portion 24 of the current lead 21 is provided in the opening of the sub-flange 25.
Is inserted and held by the mounting portion 26, and the mounting ring 35 is screwed into the thread groove formed on the outer peripheral surface of the fixing member 26b, so that the gas filling portion 24 is fixed in a depressed state. In this case, the sealing property is increased, and the reliability in preventing the deterioration of the insulation performance due to the penetration of helium gas is improved.

The current lead 21 can be securely attached to the sub-flange 25 by screwing. FIG. 4 is a cross-sectional view showing the structure of the mounting portion of the current lead in the fourth embodiment of the present invention. The same parts as those of the conventional structure shown in FIG. Now let's talk about the differences.

In the fourth embodiment, as shown in FIG. 4, a cylindrical upper gas filling portion 5b is coaxially arranged on a cylindrical gas filling portion 5a attached to the upper portion of the insulating coating portion of the current lead 1. The sub-flange 6 is fixed to the outer periphery of the gas filling portion 5a by a screwing method, and the upper gas filling portion 5b is attached to the sub-flange 6 by the mounting flange 13 to form an axially long gas filling chamber 12. . Then, the power cable 15 is connected to the connection portion 14 above the conductor 2 of the current lead 1.

As shown in FIG. 5, the power cable 15 has a lid 17 and an O-ring 1 at a seal portion 16 around the cable insertion hole provided on the upper surface of the upper gas filling portion 5b.
The gas filling chamber 12 is hermetically sealed by means of a seal 8.

As described above, in the fourth embodiment, since the connection portion 14 between the power cable 15 and the conductor 2 of the current lead 1 is placed in the space filled with the gas having high insulation performance, the insulation reliability is improved. . Further, since it is possible to prevent dew condensation and the like in the filling portion, it is possible to prevent deterioration of the insulation performance due to creeping discharge or the like.

Further, since the power cable 15 and the upper gas filling portion 5b are hermetically sealed by the sealing structure using the O-ring 18, there is an advantage that they can be easily attached and detached. In addition, in the first to third embodiments, the filling portion as shown in the fourth embodiment may be configured to connect the connecting portion to the power cable.

[0038]

As described above, according to the present invention, it is possible to provide a superconducting device capable of improving the insulation performance at the connection between the current lead and the superconducting coil and obtaining high reliability.

[Brief description of drawings]

FIG. 1 is a sectional view showing an attachment portion of a current lead in a first embodiment of a superconducting device according to the present invention.

FIG. 2 is a sectional view showing a mounting portion of a current lead according to a second embodiment of the present invention.

FIG. 3 is a sectional view showing a mounting portion of a current lead according to a third embodiment of the present invention.

FIG. 4 is a sectional view showing a mounting portion of a current lead according to a fourth embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a connection portion of a current lead in the example.

FIG. 6 is a cross-sectional view showing a mounting portion of a current lead of a conventional superconducting device.

[Explanation of symbols]

1, 21 ... Current lead, 2, 22 ... Conductor, 3, 23 ... Insulator, 5a, 5b, 24 ... Gas filling section, 24a ... Gas chamber, 6, 25 ... Sub-flange, 26 ... Mounting section, 4, 27
... Fixed flange, 28 ... Mounting screw, 29 ... Gas supply pipe,
30 ... Gas discharge pipe, 31 ... Connection part, 32 ... Electrostatic shield, 33 ... Electrode, 11, 34 ... Connection conductor, 35 ... Mounting ring, 13 ... Mounting flange, 14 ... Connection part, 15 ... Power cable, 16 ... Seal part, 17 ... Lid, 18 ... O-ring.

Claims (4)

[Claims] 1. A current lead having a refrigerant flow path for circulating a gasified refrigerant therein is connected to a superconducting coil provided by being immersed in a refrigerant liquid contained in a container, and the current lead is connected to the superconducting coil. In a superconducting device adapted to be attached to a fixed flange on the container side via a sub-flange, a portion corresponding to the fixed flange of the current lead is tapered, and a tapered surface of the current lead is provided at an opening end of the sub-flange. A superconducting device, characterized in that a mounting portion having a tapered surface matching with is provided, and the current lead is inserted into the opening of the sub-flange and held by the mounting portion for mounting. 2. The superconducting device according to claim 1,
A superconducting device, characterized in that a screw portion is provided on the atmosphere side of the taper surface of the mounting portion of the sub-flange, and the current lead is fixed by the screw portion. 3. The superconducting device according to claim 1,
A superconducting device, characterized in that a screw portion is provided on the atmosphere side of the taper surface of the mounting portion of the sub-flange, and a fixing ring is screwed onto the screw portion to fix the current lead and the sub-flange. 4. A superconducting coil provided by being immersed in a refrigerant liquid contained in a container is connected to a current lead having a refrigerant flow path for circulating a gasified refrigerant therein, and the current lead is connected to the superconducting coil. In a superconducting device adapted to be attached to a fixed flange on the container side via a sub-flange, a connecting portion for connecting a current lead to an external power cable has a size such that it exists in an insulating gas atmosphere, and a bottom portion is lower than the fixing flange surface. A superconducting device, characterized in that the current lead is provided with a gas filling portion formed so as to be located at the position.