RU70595U1 - SUPERCONDUCTING CABLE - Google Patents

Abstract

The proposal relates to superconducting cables with a current-carrying core made of a material with high-temperature superconductivity.

The technical result achieved is an increase in the resistance of the cable to short circuits while maintaining small losses on alternating current.

The superconducting cable contains a central supporting element (1), at least two coils (2, 3) of a high-temperature superconductor, electrical insulation (4) and a cryogenic shell

(5). High temperature superconductor coils are separated by a layer

(6) high resistance conductor.

The specific resistance of the layer (6) of the high-resistance conductor separating the coils (2, 3) lies in the range (5-50) 10 ^-6 ohm · cm. The layer (6) can be made of stainless steel tapes. 2 C.p.F., 1 ill.

Description

Technical field

The proposal relates to superconducting cables with a current-carrying core made of a material with high-temperature superconductivity.

State of the art

A known design of a superconducting cable, adopted as a prototype, contains a central supporting element on which at least two coils (layers) of a high-temperature superconductor are located, separated by an insulating layer (RU 2099806, Н01В 12/02, 1997).

The disadvantage of the prototype is that the cable design does not allow direct current flow between the coils due to the presence of an electrically insulating layer. In this case, during short circuits in the network, overload currents flowing from the coils to the central load-bearing element is difficult and only possible through the cable current inputs, which can lead to overheating of the high-temperature superconductor coils and their destruction. On the other hand, the complete absence of a layer separating the midwife can lead to a noticeable increase in losses in the cable when it is operated at alternating current of industrial frequency in normal mode.

Utility model creature disclosure

The objective of the utility model is to ensure the possibility of current flowing between the coils of a high-temperature superconductor in the event of a short circuit, but at the same time to maintain small losses on alternating current during normal operation.

The technical result achieved by the utility model is to increase the resistance of the cable to short circuits while maintaining low losses on alternating current.

The object of the utility model is a superconducting cable containing a central supporting element, at least two coils of a high-temperature superconductor, electrical insulation and a cryogenic sheath, characterized in that the coils of a high-temperature superconductor are separated by a layer of a high-resistance conductor.

This allows you to solve the problem of the utility model and obtain the above technical result.

The utility model has two developments related to particular cases of its implementation. According to the first development, the resistivity of a layer of a high-impedance conductor separating the coils of a high-temperature superconductor lies in the range (5-50) 10 ^-6 ohm · cm. According to a second development, the high-resistance conductor layer separating the high temperature superconductor coils is made of stainless steel tapes.

Utility Model Implementation

Figure 1 presents an example implementation of a utility model, taking into account its development. The cable comprises a central support element 1, on which the layers 2 and 3 of the high-temperature superconductor, the electrical insulation 4 and the cryogenic sheath 5 are located in layers. The powders 2 and 3 are separated by a layer 6 of the high-resistance conductor. The resistivity of the layer 6 of the high-resistance conductor lies in the range (5-50) · 10 ^-6 ohm · cm. Layer 6 can be made, for example, of stainless steel tapes.

The Central bearing element 1 consists of a mold 7, made, for example, in the form of a corrugated pipe or in the form of a spiral, a bundle of 8 copper wires superimposed on the former 7, and a copper foil 9, which is wrapped in a bundle 8.

The midwives 2 (inner) and 3 (outer) of the high-temperature superconductor are made of twenty to thirty superconducting tapes each. The directions of twisting of superconducting tapes in coils 2 and 3 are opposite: for example, left twist in cove 2 and right twist in cove 3. The number of coils is not less than two. The outer layer 3 is wrapped with a thin ribbon 10 of stainless steel that acts as a bandage. Elements 1-3 and 6-10 form a current-carrying core of a superconducting cable, on top of which there is an electrical insulation 4 in the form of paper tapes and a screen 11.

The device according to the utility model works as follows.

A shielded core is placed in a cryogenic shell 5, made in the form of a flexible long cryostat, coated on the outside with a protective sheath. During operation, the ends of the core are connected to current inputs, the conclusions of the screen 11 are grounded.

When operating as part of a superconducting cable, the current-carrying core must have, on the one hand, sufficient flexibility to wind the cable onto a drum of the appropriate diameter, and, on the other hand, rigidity, excluding bending of the cable with a radius less than permissible. These properties can be ensured by performing the mold 7 in the form of a corrugated pipe or in the form of a spiral with a given pitch and diameter.

A bundle of 8 copper wires protects the coils 2 and 3 in the event of a cable overload with a short circuit current. Protection is provided due to the transfer of part of the current from the superconductor to the beam 8. The copper foil 9 ensures the smoothness of the surface of the element 1, on which the inner core 2 is laid.

The magnitude of the pitch and the direction of twisting, with which the coils 2 and 3 are laid, provide a uniform distribution of current over the coils when working on alternating current due to the equality of the inductances of the coils 2 and 3. In the superconducting state of the coils, the current practically does not flow through the high-resistance layer 6 and this layer only performs the function of a band brace for the inner layer.

At the same time, AC losses in the cable core are as small as in the case of using an electrical insulating separation layer.

Paper electrical insulation, in addition to the main function, provides equalization of electric potential along the cable, for which it includes layers of cable semiconductor paper.

The shield 11, grounded in the current inputs, prevents electromagnetic radiation and further aligns the electric potential along the cable.

Powders 2 and 3 work as parallel conductors. The presence of a layer separating a layer 6 of a high-resistance conductor allows, in case of a short circuit, the overload current to flow from the external layer 3 into the internal layer 2 in contact with the copper elements 8 and 9. This allows maximum use of the current-carrying capacity of each layer while maintaining small losses in the cable in normal mode on alternating current. The possibility of direct current flow between the coils through the high-resistance conductor layer separating them provides increased cable resistance to short circuits.

Claims (3)

1. A superconducting cable comprising a central support member, at least two coils of a high-temperature superconductor, electrical insulation and a cryogenic sheath, characterized in that the coils of a high-temperature superconductor are separated by a layer of a high-resistance conductor. 2. The cable according to claim 1, characterized in that the resistivity of the layer of high-resistance conductor separating the high temperature superconductor coils lies in the range (5-50) 10 ^-6 Ohm · cm. 3. The cable according to claim 2, characterized in that the layer of high-impedance conductor separating the coils of the high-temperature superconductor is made of stainless steel tapes.