JPS5953777B2 - Terminals of cryogenic cables, etc. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an end portion of a cryogenic cable or the like located across both a cryogenic temperature region and a normal temperature region.

At the end of a cryogenic cable, there is a large temperature difference between the cryogenic temperature and room temperature, which poses many technical problems.

One of them is the issue of the material of the bushing cone.
It was necessary to use a special material that does not cause cracks even when subjected to heat shrinkage and thermal stress due to cooling, and to create a special structure for the terminal part so that the bushing cone would not be directly exposed to extremely low temperatures.

For example, in order to prevent cracks from forming even under extremely low temperatures,
It is necessary to use a special material such as epoxy, which has a thermal expansion coefficient similar to that of the conductor material, such as copper, even at low temperatures.

Common rubber or plastic, which is inexpensive and easily available, has a coefficient of thermal expansion that is approximately one order of magnitude larger than that of conductive metals, and even if used as is for bushing cones, cracks are likely to occur and it cannot withstand use. was known.

The present invention has been made in view of the above points, and its purpose is to provide an end portion of a cryogenic cable, etc., in which a rubber/plastic elastic body can be used as a bushing cone due to a special structure. The gist is that a flange is fixedly installed in the shape of an eave around the center of a bushing cone made of an elastic insulator made of rubber or plastic surrounding the conductor. In the terminal section of a cryogenic cable, etc., which airtightly divides the cable into a cryogenic region, the bushing cone is disposed in the boundary layer part excluding a part on the normal temperature region side at the boundary with the conductor, and is non-adhesive to the conductor. A sliding body made of a material that does not lose its flexibility even at extremely low temperatures, which tends to be slippery due to its properties, and which is integrally bonded to the upper layer of the sliding body and is in close contact with the conductor in a part of the boundary layer on the normal temperature region side. It is characterized by comprising a semiconductive layer made of rubber and plastic that are integrated.

The present invention will be explained in detail based on illustrated embodiments.

In FIG. 1, 1 is a conductor, and 2 is a spindle-shaped bushing cone surrounding the conductor 1. In FIG.

This bushing cone 2 has an electrical insulator 2' made of rubber or plastic elastic material that is flexible at room temperature.

Further, the bushing cone 2 is provided with a buffer material at its boundary with the conductor 1 to absorb thermal contraction of the bushing cone 2 at extremely low temperatures and to prevent stress from remaining in the bushing cone 2. .

Thus, in this embodiment, the cushioning material is composed of a sliding body 3, semiconducting layers 4 and 6, and a good conductor 5, which will be explained next.

That is, the conductor 1 should be covered with a synthetic polymer tape, tube, metal foil, etc., which is slippery and can be used even at extremely low temperatures, so as to be located over almost the entire length of the boundary layer between the conductor 1 and the bushing cone 2, excluding a part of the upper part. A sliding body 3 is provided, which is formed by winding a material that does not lose flexibility and is difficult to bond, and a semiconductive layer 4 made of rubber or plastic is provided on top of the sliding body 3.

Note that the sliding body 3 and the semiconductive layer 4 are integrally bonded.

Further, this semiconductive layer 4 is applied in close contact with the conductor 1 by using an adhesive or the like if necessary in the upper boundary layer where the sliding body 3 is not present.

Further, a flexible, good conductor 5 made of, for example, woven metal wire is provided on this upper layer so as to cover the sliding body 3, and a semiconductive layer 6 made of rubber or plastic is further provided on this upper layer. There is.

The electrical insulator 2' made of the rubber/plastic elastic material described above is provided on top of the electrical insulator 2'.

The semiconductive layers 4 and 6 have a sufficient thickness to absorb circumferential shrinkage of the electrical insulator 2' made of rubber/plastic elastic material at extremely low temperatures.

Furthermore, a flange 7 is provided at the center of this bushing cone 2.
is fixedly provided in the shape of a canopy, thereby airtightly dividing the bushing cone 2 into two areas, upper and lower, with the lower part being housed in the cooling container 8, and the conductor end side of the upper part being housed in the insulator tube 9.
It is stored inside.

There is a liquid level of refrigerant 10 at a certain position in cooling container 8, the lower end of bushing cone 2 is immersed in refrigerant 10, and space 11 above refrigerant 10 is filled with refrigerant pressurized gas. A space 12 within the insulator tube 9 is filled with insulating oil or electrically insulating pressurized gas.

Note that 13 is a control valve for keeping the refrigerant pressurized gas in the cooling container 8 at a constant pressure, and 14 is a heat insulating material.

Since the present invention has the above-described configuration, even if the bushing cone 2 mainly composed of the electrical insulator 2' made of a rubber/plastic elastic body is thermally shrunk in the longitudinal direction and the circumferential direction at extremely low temperatures, the longitudinal direction Regarding contraction, the electric insulator 2' made of rubber/plastic elastic material slides on the surface of the conductor 1 by the sliding member 3, so that no stress remains, and regarding contraction in the circumferential direction, the stress is absorbed by the semiconductive layers 4 and 6. As a result, no cracks or the like occur in the electrical insulator 2' made of rubber/plastic elastic material.

In addition, since the bushing cone 2 of the present invention is tightly integrated with the conductor at the upper position on the room temperature side, it is affected by cryogenic temperatures (the cone portion located on the cryogenic side is exposed to cryogenic temperatures, so this part shrinks significantly). Therefore, even if the bushing cone is made of elastic insulator made of rubber or plastic, which has greater shrinkage than epoxy and is flexible at room temperature, there is no risk of compromising airtightness. Not at all.

Note that when the sliding body 3 is made of an electrically insulating material such as Teflon, a slight potential is generated depending on the resistance of the semiconducting layers 4 and 6, and a charging current flows. This is provided for the purpose of alleviating this potential difference since there is a risk that the resistance values of the conductive layers 4 and 6 may generate heat and cause destruction.

In the embodiment shown in FIG. 2, since the sliding body 3 is made of a conductive material, there is no risk of heat generation in the semiconductive layer 46 shown in FIG. A semiconductive layer 4' made of rubber or plastic is provided on the upper layer of the moving body 3, and an electrical insulator 2' made of an elastic material of rubber or plastic is provided on the upper layer.

Note that even if an insulating material is used for the sliding body 3, the semiconducting layer 4,
Depending on the resistance value of 6, it is also possible to omit the good conductor 5.

Furthermore, in the illustrated embodiment, the lower end of the bushing cone 2 is immersed in the refrigerant 10, and since the conductor 1 is not exposed in the refrigerant pressurized gas above, this space is used to ensure a sufficient insulation distance. There is no need to increase the packing density by making 11 thicker or increasing its gas pressure.

Therefore, this terminal part can be made smaller and lighter in weight, and the smaller size also allows less heat to enter, which is economical in terms of refrigerant liquefiers and the like.

Further, although the upper part of the bushing cone 2 is covered with an insulator tube 9 for high voltage, the bushing cone 2 can be simply used even if it is exposed.

When the pressurized refrigerant gas in the cryogenic region at the lower part of the bushing cone 2 is at high pressure, in order to reduce the pressure difference with the upper part, a reinforcing tube 15 made of reinforced plastic or the like is attached to the bushing cone 2, as shown in FIG. It is also possible to fill the space 12' between the reinforcing tube 15 and the bushing cone 2 with electrically insulating oil or pressurized gas at a higher pressure than the space 12'' between the reinforcing tube 15 and the insulator tube 9. .

The terminal part according to the present invention includes a terminal part of a cryogenic cable,
It can be used for connections in cryogenic electrical equipment and electrical test equipment at cryogenic temperatures, and can be applied to stress cone type bushings, capacitor type bushings, etc.

As explained above, the terminal part of the cryogenic cable, etc. according to the present invention has a structure that absorbs the heat shrinkage of the bushing cone and does not retain stress, so the bushing is made of a rubber/plastic elastic body that can be obtained easily at low cost. It is now possible to use it as a material for cones, and there are technical issues such as manufacturing technology, material price, etc.
It has great economic advantages.

[Brief explanation of the drawing]

The drawings show an embodiment of the terminal portion of a cryogenic cable, etc. according to the present invention, and FIG. 1 is a partially cutaway front view thereof, FIG. 2 is a partially cutaway front view of a bushing cone, and FIG. 3 is a partially cutaway front view of the terminal portion. FIG. 1 is a conductor, 2 is a bushing cone, 2' is an electric insulator made of rubber or plastic elastic material, 3 is a sliding body, 4. 6
．． 4' is a semiconductive layer, 5 is a good conductor, 7 is a flange, 8
1 is a refrigerant container, 9 is an insulator tube, 10 is a refrigerant, and 15 is a reinforcing cylinder.

Claims (1)

[Claims] 1. A flange is fixedly installed in the shape of an eave around the center of a bushing cone made of an elastic insulator made of rubber or plastic surrounding the conductor, and this flange allows the conductor terminal side of the bushing cone to be kept at room temperature and the other side kept at cryogenic temperature. In the terminal portion of a cryogenic cable, etc. that is airtightly divided into regions, the bushing cone is non-adhesive to the conductor disposed in the boundary layer portion excluding a part on the normal temperature region side at the boundary with the conductor. A sliding body made of a material that is easy to slip and does not lose its flexibility even at extremely low temperatures; and a sliding body that is integrally bonded to the upper layer of the sliding body and closely integrated with a conductor in a part of the boundary layer portion on the normal temperature region side. A terminal part of a cryogenic cable, etc., characterized by comprising a semiconductive layer made of rubber or plastic.