JPH1070828A - Terminal structure for cryogenic cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a terminal structure which eliminates the generation of an evaporation gas due to the gasification of a refrigerant liquid and which prevents a drop in an insulating performance due to the gas by a method wherein the refrigerant liquid which cools a conductor derivation rod is pressurized by a gas whose boiling point is lower than that of the refrigerant liquid. SOLUTION: A gas pressurization device 13 is connected to a refrigerant gas layer 9, and a gas is supplied through the pressurization device 13 so as to pressurize a refrigerant liquid layer 8 which is used to cool a conductor derivation rod 2. As the gas which is used to pressurize the layer, a gas such as, e.g. helium, hydrogen, neon or the like, whose boiling point is lower than that of liquid nitrogen as a refrigerant liquid is used. In this manner, when the liquid nitrogen is pressurized by the gas, its boiling point is raised to about 84K from about 77K at atmospheric pressure when the pressure of the liquid nitrogen becomes two atmospheric pressure. Consequently, until the temperature of the liquid nitrogen reaches 85K, a vapor is not generated, and a gas is not generated. Thereby, it is possible to obtain a terminal part whose insulating performance is not lowered and whose reliability is high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal structure of a cryogenic cable used for an electric power transmission cable.

[0002]

2. Description of the Related Art FIG. 2A is a longitudinal sectional view of an example of a conventional terminal structure of a cryogenic cable, and FIG. 2B is an explanatory view of a problem. In the terminal of the cryogenic cable, the cooling of the cable body and the terminal is separated. A conductor 2 of a cryogenic cable body 1 such as a superconducting cable cooled by a refrigerant liquid such as high-pressure liquid nitrogen penetrates an FRP sleeve 1A covering an end of the cryogenic cable body 1 and a conductor extraction rod 3 Is connected to The conductor extraction rod 3 extends vertically through the refrigerant liquid layer 8 such as liquid nitrogen and the refrigerant gas layer 9 such as nitrogen gas in the container surrounded by the vacuum heat insulating layer 7 and penetrates the flange 12. SF6 filled inside the insulator 10
And the like are drawn out through a fluid insulating layer 11. The conductor drawing rod 3 is provided with an insulating coating layer 4 of ethylene propylene rubber or the like from near the liquid surface of the refrigerant liquid layer 8 to the middle of the fluid insulating layer 11, and further near both ends of the insulating coating layer 4. Stress cones 5 and 6 are mounted.

[0003]

In the terminal of the cryogenic cable having the above-mentioned structure, the lower end portions of the insulating coating layer 4 and the stress cone 5 located in the refrigerant liquid layer 8 are formed as shown in FIG.
As shown in FIG. 2, since the refrigerant liquid is formed in a direction perpendicular to the axial direction of the conductor extraction rod 1, when the refrigerant liquid is vaporized by invasion heat or Joule heat of the conductor extraction rod 3, portions A and B in FIG. There is a possibility that the evaporative gas accumulates. In general, the insulation strength between the evaporative gas and the liquid is smaller in the case of the evaporative gas.
In V / mm, the ratio is 9: 1. When this vaporized gas is suspended in the refrigerant liquid layer 8, there is a danger that insulation strength is reduced and dielectric breakdown is caused.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a terminal structure of a cryogenic cable in which the generation of evaporative gas due to the vaporization of refrigerant liquid is provided. In a terminal structure of a cryogenic cable, in which an insulating coating layer and a stress cone are provided on a conductor drawing rod for drawing a cable conductor from a cryogenic part to a room temperature part, a refrigerant liquid for cooling the conductor drawing rod has a boiling point higher than the refrigerant liquid. The terminal structure of a cryogenic cable pressurized with a gas having a low temperature.

[0005]

FIG. 1 is a longitudinal sectional view of a specific example of a terminal structure of a cryogenic cable according to the present invention. In the drawings, the same reference numerals as those in FIG. 2A denote the same parts.
The conductor 2 of the cryogenic cable main body 1 penetrates the FRP sleeve 1A that covers the end of the cryogenic cable main body 1, and is connected to the conductor drawing rod 3. The conductor extraction rod 3 extends vertically through the refrigerant liquid layer 8 and the refrigerant gas layer 9 in the container surrounded by the vacuum insulation layer 7, penetrates through the flange 12, and
0 is drawn out through a fluid insulating layer 11 such as SF6 filled inside. The conductor withdrawal rod 3 is provided with an insulating coating layer 4 from near the liquid surface of the refrigerant liquid layer 8 to the middle of the fluid insulating layer 11, and stress cones 5 and 6 are provided near both ends of the insulating coating layer 4. It is installed.

In the terminal structure of the present invention, a gas pressurizing device 13 is connected to the refrigerant gas layer 9, and gas is supplied through the pressurizing device 13 to pressurize the refrigerant liquid layer 8. As a gas used for pressurization, helium, hydrogen, neon, or the like having a lower boiling point than liquid nitrogen is used. By pressurizing liquid nitrogen or the like with a gas as described above, for example, when the pressure of liquid nitrogen becomes 2 atm, the boiling point increases from the atmospheric pressure of about 77K to about 84K. Therefore, no evaporation occurs until the temperature of the liquid nitrogen reaches 84 K, and no gas is generated.

[0007] When the intrusion heat or Joule heat is generated for a long time, the temperature of the refrigerant liquid such as liquid nitrogen gradually rises, and eventually reaches the boiling point at that pressure. Therefore, as shown in FIG.
If the refrigerant liquid layer 8 is cooled through the heat exchange section 15 and the capacity of the refrigerator 14 is made equal to the intrusion heat or Joule heat, the temperature of the refrigerant liquid layer 8 does not rise, and the evaporative gas Is gone.

[0008]

As described above, according to the terminal structure of the cryogenic cable of the present invention, there is no generation of evaporative gas due to the vaporization of the refrigerant liquid, and there is no decrease in insulation performance due to this. Part is obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a specific example of a terminal structure of a cryogenic cable according to the present invention.

FIG. 2A is a longitudinal sectional view of an example of a conventional cryogenic cable terminal structure, and FIG. 2B is an explanatory diagram of a problem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cryogenic cable main body 2 Cable conductor 3 Conductor lead-out rod 4 Insulation coating layer 5, 6 Stress cone 7 Vacuum barrier layer 8 Refrigerant liquid layer 9 Refrigerant gas layer 10 Insulator 11 Fluid insulation layer 12 Flange 13 Gas pressurizer 14 Refrigerator 15 Heat exchange section

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeo Nagaya 20-1 Kitakanyama, Odaka-cho, Midori-ku, Nagoya-shi, Aichi Prefecture Inside Chubu Electric Power Co., Inc. (72) Inventor Takaaki Shimonosono Midori-ku, Nagoya-shi, Aichi Otakamachi character Kita-Kanzan 20 No. 1 Chubu Electric Power Co., Inc.

Claims (1)

[Claims] 1. A refrigerant liquid for cooling a conductor of a cryogenic cable in a terminal structure of the cryogenic cable, wherein an insulating coating layer and a stress cone are provided on a conductor drawing rod for drawing a conductor of the cryogenic cable from a cryogenic part to a room temperature part. Cryogenic cable is pressurized with a gas having a lower boiling point than the refrigerant liquid.