Superconducting fault current limiter and cooling method for superconducting element within superconducting fault current limiter

Patent metadata

Field	Value
Publication number	US-10178799-B2
Application number	US-201414767878-A
Country	US
Kind code	B2
Filing date	Feb 7, 2014
Priority date	Feb 13, 2013
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

A superconducting fault current limiter (10) is provided with superconducting elements (71, 72) that are in a superconducting state during electrification with a current value in a fixed range and in a normal conducting state during electrification with a fault current in which the current value exceeds the fixed range and is further provided with a coolant vessel (20), which accommodates a liquid coolant (60) and a plurality of superconducting elements, and a cooling means (40) that cools the liquid coolant within the coolant vessel. Within the liquid coolant, the superconducting element (71) for which the critical current is smallest among the plurality of superconducting elements is disposed on the upper side of any other superconducting elements (72). Thus, the superconducting element (71) is cooled, and the life of the superconducting fault current limiter as a whole is extended.

First claim

The invention claimed is:

1. A superconducting fault current limiter comprising superconducting elements which are in a superconducting state when an electric current flows within a range of electric current values and which change to a normal conducting state when a fault current flows exceeding the range, comprising:
a coolant vessel which accommodates a liquid coolant and the superconducting elements; and
a cooling means which cools the liquid coolant in the coolant vessel, wherein among the superconducting elements, a first superconducting element with a lowest critical current is disposed over a second superconducting element in the liquid coolant and wherein vaporized gas bubbles from the second superconducting element assist vaporized gas, on a surface of the first superconducting element, to be released.

2. The superconducting fault current limiter according to claim 1 , wherein the superconducting elements are disposed in the liquid coolant such that a superconducting element with a lower critical current is located at a higher location in the liquid coolant than another superconducting element with a higher critical current than the lower critical current of the superconducting element.

3. The superconducting fault current limiter according to claim 1 , wherein the superconducting elements are arranged in a plane parallel to a vertical direction, and wherein each pair of vertically adjacent two superconducting elements is disposed such that an upper superconducting element has a lower critical current than a lower superconducting element.

4. The superconducting fault current limiter according to claim 3 , wherein a plurality of sets, each composed of the superconducting elements arranged in the plane parallel to the vertical direction, is arranged such that the superconducting elements are disposed three-dimensionally as a whole.

5. The superconducting fault current limiter according to claim 1 , further comprising an element cover which has open upper and lower ends and which is disposed in the coolant vessel surrounding the superconducting elements.

6. A superconducting fault current limiter comprising a plurality of superconducting elements which are in a superconducting state when an electric current flows within a certain range of electric current values and which change to a normal conducting state when a fault current flows exceeding the certain range, comprising:
a coolant vessel which accommodates a liquid coolant and the plurality of superconducting elements; and
a cooling means which cools the liquid coolant in the coolant vessel, wherein at least two superconducting elements of the plurality of superconducting elements are vertically arranged in the liquid coolant, such that vaporized gas bubbles from a lower element of the at least two superconducting elements assists a release of vaporized gas on a surface of a higher element of the at least two superconducting elements, and wherein the superconducting fault current limiter further comprises an element cover which has open upper and lower ends and which surrounds the at least two superconducting elements.

7. The superconducting fault current limiter according to claim 6 , wherein a lower superconducting element of the at least two superconducting elements surrounded by the element cover is disposed such that a lower end of the lower superconducting element is located higher than a lower end of the element cover.

8. The superconducting fault current limiter according to claim 6 ,
wherein the at least two superconducting elements are disposed such that the following expression (I) is satisfied,
tan −1 ( L/R )≤70°  (I)

where R is a distance from centers of the at least two superconducting elements to an inner surface of the element cover in a longitudinal direction in a plan view of the at least two superconducting elements, and L is an inter-center distance between the at least two superconducting elements in a vertical direction of the at least two superconducting elements.

9. A cooling method for superconducting elements in a superconducting fault current limiter which comprises the superconducting elements which are in a superconducting state when an electric current flows within a certain range of electric current values and which change to a normal conducting state when a fault current flows exceeding the certain range, comprising:
disposing the superconducting elements such that a superconducting element with a lowest critical current is located over another superconducting element in a liquid coolant in a coolant vessel; and
cooling the superconducting element with the lowest critical current by using bubbles which are produced on the other superconducting element disposed below the superconducting element with the lowest critical current.

10. The cooling method for the superconducting elements in the superconducting fault current limiter according to claim 9 , wherein the superconducting element with the lowest critical current is cooled when the liquid coolant is in a film boiling state on a surface of the superconducting element with the lowest critical current.

11. The cooling method for the superconducting elements in the superconducting fault current limiter according to claim 9 , wherein the superconducting elements are disposed in the liquid coolant such that a first superconducting element with a lower critical current than a second super conducting element with a higher critical current is at a higher location than the second super conducting element.

12. The cooling method for the superconducting elements in the superconducting fault current limiter according to claim 9 , wherein the superconducting elements are arranged in a plane parallel to a vertical direction, and wherein the superconducting elements are disposed such that an upper superconducting element of each pair of vertically adjacent two superconducting elements has a lower critical current than a lower superconducting element.

13. The cooling method for the superconducting elements in the superconducting fault current limiter according to claim 12 , wherein a plurality of sets, each composed of the superconducting elements arranged in the plane parallel to the vertical direction, are disposed so that the superconducting elements are disposed three-dimensionally as a whole.

14. The cooling method for the superconducting elements in the superconducting fault current limiter according to claim 9 , wherein the superconducting elements are disposed in an element cover which has open upper and lower ends and which is disposed in the coolant vessel.

15. A cooling method for a plurality of superconducting elements in a superconducting fault current limiter which comprises the plurality of superconducting elements which are in a superconducting state when an electric current flows within a range of electric current values and which change to a normal conducting state when a fault current flows exceeding the range, comprising:
disposing vertically at least two of the plurality of superconducting elements in an element cover which has open upper and lower ends and which is disposed in a liquid coolant in a coolant vessel, resulting in at least two vertically arranged superconducting elements; and
leading bubbles produced on a lower superconducting element of the plurality of superconducting elements toward an upper superconducting element of the plurality of superconducting elements.

16. The cooling method for the plurality of superconducting elements in the superconducting fault current limiter according to claim 15 , wherein the upper superconducting elem

Assignees

• Furukawa Electric Co Ltd

Inventors

• Kasahara Hajime
• Nakayama Tomohiro
• Matsui Masakazu

Classifications

• H05K7/20236 Primary

  by immersion · CPC title

• H02H9/023

  Current limitation using superconducting elements · CPC title

• H01L39/16

  Electricity · mapped topic

• Y02E40/68

  Cross-Sectional Technologies · mapped topic

• H02H7/001 Primary

  for superconducting apparatus, e.g. coils, lines, machines · CPC title