RU2588607C1 - High-voltage current lead of superconducting short-circuit current limiter - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: proposed engineering solution relates to superconducting power of electric engineering and can be used for connection to electric network of high-voltage superconducting current limiter of short-circuit in cryostat with liquid nitrogen. Current leads (3) and (4) are located coaxially. Current lead (3) protrudes from current distributor (4). Top ends of current leads (3) and (4) are complete with terminals for connection to electric network. Lower ends of current leads (3) and (4) are immersed in liquid nitrogen, filling cryostat (2). Nitrogen vapour in cavity of current lead (4) serves as gaseous insulation between current conductors (3) and (4). Insulator (5) electrically separates protruding part of current lead (3) of current distributor (4). Insulator (6) electrically separates the cover (7) of current distributor (4). In upper part of cryostat (2) there is dielectric heat screen (8), covering external current lead (4).

EFFECT: decreased overall dimensions and heat transfer from external medium in cryostat high-voltage device.

1 cl, 1 dwg

Description

The proposed technical solution relates to the field of superconducting power electrical engineering and can be used to connect to the electric network a high-voltage superconducting short-circuit current limiter placed in a cryostat with liquid nitrogen.

A device is known (Patent JP 2009268340 A, IPC H01R 4/68, H02G 15/34, published 12.11.2009) for connecting an electric superconducting apparatus to a power source, according to which the connection is made by insulated conductors through the dielectric cover of the cryostat.

This device does not provide electrical strength sufficient for high-voltage apparatus.

The closest analogue (prototype) is the solution (Patent US 2008119077 A1, IPC H01R 13/53, H02G 15/34, published May 22, 2008), in which the current lead of a high-voltage superconducting current limiter located in a cryostat with liquid nitrogen contains two separate current conductors isolated from cryostat and from each other. The conductors of the prototype have solid insulation. To ensure electrical strength, the upper ends of the bushings in which the conductors are located are spaced apart over a long distance.

The disadvantage of the prototype is that in its design, ensuring electrical strength requires a significant increase in the dimensions of the device, and an increase in dimensions, in turn, increases the total heat transfer to the cryostat.

Disclosure of the invention

The proposed design provides a technical result, consisting in reducing the dimensions of the device required to ensure electrical strength, and, as a result, reducing heat transfer from the external environment to the cryostatic high-voltage apparatus.

The subject of the invention is the current lead of a high voltage superconducting current limiter located in a cryostat with liquid nitrogen, containing two vertical conductors isolated from the cryostat and from each other, characterized in that the conductors are made coaxially in the form of external and protruding internal conductors, separated by gas insulation and equipped with a first finned insulator separating the protruding part of the internal current path from the external current path, and a second finned insulator separating external conductor from the cryostat, while in the upper part of the cryostat a dielectric heat shield is installed, covering the external conductor.

The design of the proposed device is illustrated in the drawing.

The drawing shows:

1 - high voltage superconducting limiter (COT) short circuit current;

2 - cryostat;

3 - internal conductor;

4 - external conductor;

5 - the first finned insulator;

6 - the second finned insulator;

7 - cryostat cover;

8 - dielectric heat shield.

Conductors 3 and 4 are located coaxially. The conductor 3 protrudes from the conductor 4. The upper ends of the conductors 3 and 4 have terminals for connecting to the electrical network. The lower ends of the conductors 3 and 4 are connected to COT 1, which is immersed in liquid nitrogen filling the cryostat 2. The nitrogen vapor in the cavity of the current lead 4 serves as a gaseous insulation between the conductors 3 and 4. The insulator 5 electrically separates the protruding part of the current lead 3 from the current lead 4. Insulator 6 electrically separates the cover 7 from the conductor 4.

In the upper part of the cryostat 2 is installed a dielectric heat shield 8, covering the conductor 4.

The device operates as follows.

In the operating mode (at operating currents), COT 1 is in a superconducting state and there is no voltage between the coaxially located conductors 3 and 4. When a short circuit current flows through the COT, it leaves the superconducting state and a high voltage arises between the conductors 3 and 4. In this case, the electric strength of the gap between the conductors 3 and 4 is ensured by gas insulation formed by the vapor of liquid nitrogen and the insulator 5. The electric strength of the gap between the current lead 4 and the cryostat 2 with the cover 7 is provided by the insulator 6.

The dielectric heat shield 8 reduces the influx of heat through the conductors 3 and 4 into the cryostat and increases the temperature of its cover 7, preventing it from freezing, which reduces the electric strength.

Coaxial arrangement of conductors 3 and 4 electrically separated by gas insulation in the form of nitrogen vapor, the use of an insulator 5 separating the protruding part of the current lead 3 from the current lead 4, an insulator 6 separating the lid 7 of the cryostat 2 from the current lead 4, and the heat shield 8 provides a compact design of the device when meeting the requirements for electric strength and, as a consequence, reducing heat transfer from the external environment to a cryostatic high-voltage apparatus 1.

Claims (1)

The current lead of a high-voltage superconducting current limiter located in a cryostat with liquid nitrogen, containing two vertical conductors isolated from the cryostat and from each other, characterized in that the conductors are made coaxially in the form of an external and protruding internal conductors, separated by gas insulation and equipped with a first finned an insulator separating the protruding portion of the internal current path from the external current path, and a second finned insulator separating the external current path from the cryostat while a dielectric heat shield is installed in the upper part of the cryostat, covering the external conductor.

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