JPH05114754A - Current lead insulating support structure of superconductive equipment - Google Patents

Abstract

PURPOSE:To prevent troubles such as breakage of a bellows and a ceramic tube by a method wherein reinforcements whose upper lower end are linked to an upper flange provided to the normal-temperature terminal of a current lead and a lower flange connected to a vacuum heat insulating chamber respectively are provided. CONSTITUTION:The upper and the lower end of a reinforcing member 20 are linked and fixed to an upper flange 5 provided to the normal-temperature terminal 1A of a current lead 1 and a lower flange 6 connected to a vacuum heat insulating chamber 2 respectively. The reinforcing member 20 is arranged in a dry coolant gas atmosphere shut off from the outside air, and a cylindrical insulator (FRP tube) 21 can be protected against contaminants. By this setup, a normal-temperature port 7 can be mechanically reinforced without deteriorating a ceramic tube 3 in voltage-resistant properties, a current lead 1 can be prevented from swinging due to an external force, and troubles such as the deformation of a bellows 4 or breakage of the ceramic tube 3 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating support structure for a current lead for supplying an exciting current from an external power source to a superconducting device such as a superconducting magnet having a high voltage and a large capacity.

[0002]

2. Description of the Related Art A superconducting device such as a superconducting magnet is inserted from the outside into a vacuum heat insulating container for holding the superconducting device while holding the superconducting state, and a current lead for passing an exciting current from an external power source to the superconducting device main body is In some cases, the flowing current exceeds 10 KA, and the cross-sectional area and weight of the conductor are large, so high mechanical strength is required for the insulating support structure. Also, since the low temperature terminal side of the current lead becomes extremely low temperature, its heat effect extends to the room temperature terminal, and moisture in the atmosphere freezes or condenses on the outside air side of the room temperature terminal or the insulating support structure, and Since the heat generated by the flow of heat melts and wets the surface of the insulating material to cause wet fouling, an insulating structure having high wet fouling resistance is required to maintain the withstand voltage performance.

FIG. 3 is a side sectional view showing a conventional current lead insulating and supporting structure of a superconducting device, and FIG. 4 is a plan view of a main part of FIG. 3 seen from above. In the figure, the current lead 1 is inserted into the vacuum heat insulating container 2 while being insulated and supported by the room temperature port 7, and is immersed in a cooling medium such as liquid helium in the vacuum heat insulating container 2 to maintain the superconducting state. An exciting current from a room temperature terminal 1A that is conductively connected to a superconducting device such as a superconducting magnet (not shown) and conductively connected to an external power source is passed to the superconducting device. In addition, the room temperature port 7 includes the upper flange 5 provided near the room temperature terminal 1A of the current lead, and the vacuum insulation container 2
It is composed of a lower flange 6 which is connected to the side in a sealed manner and a series body of ceramic porcelain tube 3 and a bellows 4 which connect the flanges 5 and 6 to each other in a sealed manner. , Evaporated refrigerant gas (eg helium gas)
Define a filled space, through which the main part of the current lead is inserted into the vacuum insulation container 2.

The room temperature port 7 constructed as described above is
Connection of conductors to room temperature terminals, external force due to earthquake, etc., or excessive axial force due to electromagnetic force acting on the current lead when current is interrupted, external force such as bending load, twisting load, etc. applied to the ceramic porcelain tube In order to prevent the above, and in order to absorb the thermal stress due to the temperature difference, the ceramic porcelain tube 3 is provided with the bellows 4 in series, so that there occurs the inconvenience that the current lead sways each time the external force is applied. Therefore, in order to avoid such an inconvenience, the reinforcing portion 10 in which the protective insulating cylinder 11 is connected to the support seats 12 and 13 radially protruding from the flanges 5 and 6 using the bolts 14 is used.
Is provided outside the room temperature port 7 and absorbs the external force to prevent the current lead from shaking or vibrating due to the external force. It has already been proposed (1991 Utility Model Publication No. 7966).

In the current lead insulating support structure having the above-mentioned reinforcing portion 10, the rigidity of the protective insulating cylinder formed in a tubular shape and having a large section modulus is utilized to make use of the pair of flanges 5, 5.
Since the six members can be firmly connected to each other, there is little change with respect to a dynamic external force, and an insulating support structure for the current lead can be obtained without the risk of the deformation of the bellows due to the external force or the damage of the ceramic porcelain tube due to an excessive external force. By the way, the conventional reinforcing portion 1
0, a fiber reinforced plastic cylinder (FRP tube) is used as the protective insulating cylinder 11 because high rigidity and withstand voltage performance are required, and its length is the length of the ceramic porcelain tube 3 which is structurally a room temperature port. It is formed to have a dimension that is sufficiently longer than the length. Therefore, when the ceramic porcelain tube or the protective insulating tube is dry, the withstand voltage of the current lead insulating support structure is determined by the creepage insulation distance of the ceramic porcelain tube 3. Therefore, the creepage insulation distance of the ceramic porcelain tube 3 is determined on the assumption that the freezing of the surface of the room temperature terminal 1A and the room temperature port 7 is melted by the heat generated by the flow of the electric current and the surface of the ceramic porcelain tube becomes wet. It has been considered that a room temperature port having the required withstand voltage performance can be constructed.

[0006]

However, the reinforcing portion 10
In a high voltage current lead insulation support structure having
When the surfaces of the ceramic porcelain tube and the protective insulating tube become wet (called wet stain), creeping dielectric breakdown occurs on the surface of the protective insulating tube 13 made of an FRP tube having a longer creeping insulation distance than the ceramic porcelain tube. However, it has been found that there is a problem in that an insulating support structure for a current lead having a desired withstand voltage performance cannot be obtained, and an improvement thereof is required.

An object of the present invention is to obtain a current lead insulating support structure for a superconducting device which can mechanically protect a room temperature port without affecting the withstand voltage performance and thus can prevent the current lead from swinging due to an external force. It is in.

[0008]

In order to solve the above-mentioned problems, according to the present invention, a lower flange connected to a vacuum heat insulating container for holding a superconducting device while holding its superconducting state, and the superconducting device are provided. A current-supplying current lead is provided with a room temperature port which is connected to an upper flange provided on the room temperature terminal side through a ceramic porcelain tube and a bellows series body, and shuts off the main part of the current lead from the outside air. In such a state that it is insulated and supported, a normal temperature port isolated from the outside air is made of a cylindrical insulating material arranged substantially coaxially so as to surround the current lead, and the upper and lower ends thereof are the upper flange. And a reinforcing portion connected to the lower flange, respectively.

Further, the reinforcing portion fixes the fiber reinforced plastic cylinder as a tubular insulating material, the support seat radially protruding from the pair of upper and lower flanges, and the fiber reinforced plastic cylinder to the support seat. It shall consist of a bolt and.

Further, the support seats radially protruding from the lower flange and the bolts connected to the support seats are made of an insulating material.

[0011]

The structure of the present invention, as a result of pursuing the cause that the withstand voltage performance is significantly lowered due to wet contamination of the protective insulating cylinder having a longer creepage insulation distance than that of the ceramic porcelain tube,
In the case of a ceramic porcelain tube, even if a leakage current flows through a wet creeping surface, the heat generated by the leakage current evaporates water and the surface of the ceramic porcelain tube dries, and the ceramic material, which is an excellent heat-resistant inorganic material, withstands the heat generated by the current. Since a carbonized current path (called tracking) is not formed, insulation recovery is excellent, and the withstand voltage performance is not significantly degraded. On the other hand, in the case of the protective insulating cylinder made of FRP material, the plastic of the surface layer of the FRP material is carbonized due to the heat generated by the leakage current, so tracking is likely to occur, and the self-healing property of the insulation is low. The fact that dielectric breakdown is likely to develop has been found, and it is constructed as follows based on the obtained fact. That is, a reinforcement made of a cylindrical insulating material which is arranged substantially coaxially so as to surround the current lead in a room temperature port which is shielded from the outside air, and whose upper and lower ends are respectively connected to the upper flange and the lower flange. Since the normal-temperature port is mechanically reinforced from the inside by arranging the part, it is possible to avoid swaying of the current lead due to external force and the accompanying damage to the bellows, the ceramic porcelain tube, etc. In a dry refrigerant gas atmosphere defined by the ambient temperature port as the outside air, the withstand voltage performance of the cylindrical insulating material is normally maintained. Decrease in withstand voltage performance is small The creepage insulation distance of the ceramic porcelain tube determines the decrease in withstand voltage performance due to wetting of the reinforcement part almost completely, so it does not affect the withstand voltage performance at room temperature. - the ability to strengthen the door mechanically can be obtained.

The tubular insulating material is made of a fiber reinforced plastic cylinder (FRP tube).
By constructing the reinforcing part by connecting the bolts that penetrate the tube to the support seats that are radially projected from the pair of upper and lower flanges, respectively, the high rigidity of the FRP tube and the excellent withstand voltage performance in a dry state can be obtained. By utilizing and, it is possible to obtain the function of ensuring mechanical stability against external force and insulation performance against wet fouling.

Further, if the support seats radially protruding from the lower flange and the bolts connected to the support seats are made of an insulating material, the reinforcing portion can be supported at room temperature without increasing the inner diameter of the room temperature port. -It can be provided inside.

[0014]

EXAMPLES The present invention will be described below based on examples. FIG. 1 is a side sectional view showing a current lead insulating and supporting structure of a superconducting device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA in FIG. Duplicated description will be omitted by giving reference numerals. In the figure, the upper flange 5 of the room temperature port 7 is divided into a flange 5A on the side of the current lead 1 and a flange 5B on the side of the bellows 4, and the two are airtightly bolted through packing to allow room temperature. A refrigerant gas space 27 isolated from the outside air is formed inside the port 7, and the current lead 1 is easily attached to and detached from the room temperature port 7. The reinforcing portion 20 is provided in the refrigerant gas space 27 that is shielded from the outside air by the room temperature port 7, and is a cylindrical insulating material, for example, FR, which is arranged substantially coaxially so as to surround the current lead 1.
The P-tube 21 and support seats 22 and 23 radially protruding from the pair of upper and lower flanges 5B and 6, respectively.
And a bolt 24 penetrating the FRP tube and fixing the FRP tube to the support seat. Further, in the assembling work of the current lead insulating and supporting structure, if the reinforcing portion 20 is previously bolted inside the room temperature port 7, the work of attaching to the vacuum insulation container 2 and then the work of attaching the current lead 1 are performed. Well, by dividing the upper flange 5 into 5A and 5B, the assembling work of the reinforcing portion is facilitated.

In the current lead insulating and supporting structure for superconducting equipment constructed as described above, the reinforcing portion 20 mechanically reinforces the room temperature port 7 from its inner side, and the reinforcing portion 2
Since 0 is placed in a dry refrigerant gas atmosphere that is cut off from the outside air to prevent wet contamination of the FRP tube, the room temperature port is mechanically reinforced without impairing the withstand voltage performance of the ceramic porcelain tube. The current lead 1 can be prevented from swaying due to an external force, and the swaying of the current lead can be suppressed, so that the progress to a serious accident such as deformation of the bevel 4 or damage to the ceramic insulator tube 3 can be prevented. it can.
Further, the withstand voltage performance of the room temperature port 7 is determined by the creepage insulation distance of the ceramic porcelain tube 3, and it is possible to obtain a current lead insulation support structure having high insulation reliability by utilizing the wet stain resistance of the ceramic porcelain tube. it can.

In the reinforcing portion 20, both the support seat 22 projecting from the lower flange 6 and the bolt 24 connected to the support seat 22 may be made of an insulating material. A lower flange 6 and
Since it is possible to prevent the insulation distance from the current lead 1 at a high potential from being shortened by the support seats and bolts protruding from the lower flange and degrading the withstand voltage performance of this portion, it is necessary to install the reinforcing portion internally. It is possible to obtain an advantage that the diameter of the room temperature port 7 is prevented from increasing due to the above, and the reinforcing portion can be downsized by using the FRP tube whose diameter is reduced as compared with the conventional protective insulating cylinder.

[0017]

As described above, the present invention comprises a cylindrical insulating material which is coaxially arranged so as to surround a current lead in a room temperature port which is insulated from the outside air, and whose upper and lower ends are upper parts. It is configured to include a reinforcing portion connected to each of the flange and the lower flange. As a result, the room temperature port is mechanically reinforced from the inside to prevent the current lead from swaying due to an external force and the resulting damage to the bellows, the ceramic porcelain tube and the like. Wet fouling is avoided in a dry refrigerant gas atmosphere defined as, and the withstand voltage of the room temperature port can be determined by the creepage insulation distance of the ceramic porcelain tube in which the decrease in withstand voltage performance due to wet fouling is small. This makes it possible to almost completely eliminate the deterioration of the withstand voltage performance due to the wet contamination of the protective insulating cylinder, which has been a problem in the prior art. Therefore, it is possible to provide a superconducting device having a current lead insulating support structure having a function of mechanically strengthening a room temperature port without affecting the withstand voltage performance.

The tubular insulating material is a fiber reinforced plastic cylinder (FRP tube).
If the tube is configured to be bolted to the support seats radially protruding from each of the pair of upper and lower flanges, the high rigidity of the FRP tube and the excellent withstand voltage performance in a dry state are utilized to apply an external force. It is possible to economically and advantageously provide a superconducting device provided with a current lead insulating support structure having excellent mechanical stability against heat damage and excellent insulation reliability against wet fouling.

Further, if the support seats radially protruding from the lower flange and the bolts connected to the support seats are made of insulating material, the inner diameter of the room temperature port can be prevented from increasing and the reinforcing portion can be made to be conventional. The advantage that it can be made smaller can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing a current lead insulation support structure for a superconducting device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

FIG. 3 is a side sectional view showing a conventional current lead insulation support structure for a superconducting device.

FIG. 4 is a plan view of a main part when FIG. 3 is viewed from above.

[Explanation of symbols]

 1 Current Lead 1A Room Temperature Terminal 1B Low Temperature Terminal 2 Vacuum Insulation Container 3 Ceramic Insulator Tube 4 Bellows 5 Upper Flange 6 Lower Flange 7 Room Temperature Port 10 Reinforcement 11 Protective Insulation Cylinder (FRP Tube) 12 Support Seat 13 Support Seat 14 Bolts 20 Reinforcement part 21 Cylindrical insulator (FRP tube) 22 Support seat 23 Support seat 24 Bolt 27 Refrigerant gas space

Claims (3)

[Claims] 1. A ceramic comprising a lower flange connected to a vacuum heat insulation container for holding the superconducting device while holding the superconducting state, and an upper flange provided on a room temperature terminal side of a current lead for supplying a current to the superconducting device. An ordinary temperature port which is insulated from the outside air, which is provided with an ordinary temperature port connected through a series body of an insulator and a bellows and which insulates and supports the main portion of the current lead from the outside air. A cylindrical insulating material arranged substantially coaxially so as to surround the current lead, and upper and lower ends thereof are respectively connected to the upper flange and the lower flange, and a reinforcing portion is provided. Current lead insulation support structure for superconducting equipment. 2. A reinforcing portion, a fiber-reinforced plastic cylinder as a tubular insulating material, a support seat radially protruding from a pair of upper and lower flanges, and the fiber-reinforced plastic cylinder fixed to the support seat. The current lead insulating and supporting structure for a superconducting device according to claim 1, characterized in that it comprises a bolt. 3. A current lead insulating support structure for a superconducting device according to claim 2, wherein the support seats radially protruding from the lower flange and the bolts connected thereto are made of an insulating material.