SUPERCONDUCTING FAULT CURRENT LIMITER

• US 20110026170A1
• Filed: 03/05/2009
• Published: 02/03/2011
• Est. Priority Date: 04/04/2008
• Status: Active Grant

• Current Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Original Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Inventors: Smith, Alexander C., Husband, Stephen M.
• Granted Patent: US 8,848,323 B2
• Time in Patent Office: Days
• US Class Current: 361/19
• CPC Class Codes: H10N 60/30 Devices switchable between superconducting and normal states

Abstract

A superconducting fault current limiter comprises a superconducting element having a plurality of superconducting portions and at least connector. Each superconducting portion has end regions and each connector is connected to the end regions of adjacent superconducting portions to electrically and thermally connect adjacent superconducting portions of the superconducting fault current limiter together. Each connector provides a local reduction in the critical current and quench current of the end regions of the superconducting portions in contact with the at least one connector. This provides a phased transition of the superconducting fault current limiter in relation to the severity of a fault current.

Claims

1-15. -15. (canceled)

16. A superconducting fault current limiter comprising a superconducting element and means to produce a local increase of temperature of the superconducting element to provide a local reduction in the critical current and quench current of the superconducting element.

17. A superconducting fault current limiter as claimed in claim 16 wherein the superconducting element having a plurality of superconducting portions and at least one connector, each superconducting portion having end regions, each connector being connected to the end regions of adjacent superconducting portions to electrically and thermally connect adjacent superconducting portions of the superconducting fault current limiter together such that each connector provides a local reduction in the critical current and quench current of the end regions of the superconducting portions in contact with the at least one connector.

18. A superconducting fault current limiter as claimed in claim 17 wherein the at least one connector comprises a metal.

19. A superconducting fault current limiter as claimed in claim 18 wherein the at least one connector comprises copper.

20. A superconducting fault current limiter as claimed in claim 17 wherein the superconducting portions comprise magnesium diboride.

21. A superconducting fault current limiter as claimed in claim 17 wherein the superconducting portions and the at least one connector are arranged around a former.

22. A superconducting fault current limiter as claimed in claim 21 wherein the superconducting portions and the at least one connector are wound in a coil around the former.

23. A superconducting fault current limiter as claimed in claim 16 wherein the ends of the superconducting fault current limiter are connected to an electrical circuit by end connectors.

24. A superconducting fault current limiter as claimed in claim 23 wherein the end connectors comprise copper.

25. A superconducting fault current limiter as claimed in claim 23 wherein the end connectors are arranged in contact with a cooler.

26. A superconducting fault current limiter as claimed in claim 17 wherein the at least one connector is not arranged in contact with a cooler.

27. A superconducting fault current limiter as claimed in claim 17 comprising a plurality of connectors.

28. A superconducting fault current limiter as claimed in claim 16 wherein the means to produce a local increase of temperature of the superconducting element comprising a first epoxy resin with a first predetermined thermal conductivity positioned at one or more positions in a groove on a former, a second epoxy resin with a second predetermined thermal conductivity positioned in the remainder of the groove and the first epoxy resin having a lower thermal conductivity than the second epoxy resin, the superconducting element being located in the groove in the former by the epoxy resin.

29. A superconducting fault current limiter as claimed in claim 16 wherein the means to produce a local increase of temperature of the superconducting element comprising at least one region with a local increases in the depth of a groove in a former, the at least one region being arranged at one or more positions in the groove of the former, the superconducting element being located in the groove in the former by an epoxy resin, the former having a greater thermal conductivity than the epoxy resin,

30. A superconducting fault current limiter as claimed in claim 16 wherein the means to produce a local increase of temperature of the superconducting element comprising an additional high magnetic permeability cylindrical sleeve around a portion of the superconducting element to increase the local magnetic field.