Fault current limiter with shield and adjacent cores

1. In a fault current limiter (FCL) of a saturated high permeability core type having at least one phase coil wound around a high permeability material, a method of suppressing a voltage differential during a fault zero current condition, comprising:

utilizing one of an electromagnetic screen or an electromagnetic shield around the phase coil to suppress a time derivative of current waveform levels during zero current conditions.

2. The method of claim 1 , wherein the fault current limiter includes

first and second high permeability columns;

first phase coil wound around the first high permeability column;

second phase coil wound around the second high permeability column; and

high permeability saturation unit surrounding the first and second high permeability columns for substantially saturating the columns during non fault operation, and

wherein the electromagnetic screen or shield is formed around the first and second phase coils.

3. The method as claimed in claim 2 , wherein the screen or shield is placed between the phase coils and the magnetic saturation unit so as to reduce the AC flux in the vicinity of the magnetic saturation unit.

4. The method as claimed in claim 2 , wherein the electromagnetic shield is separate from the structure or any dielectric system of the FCL.

5. The method as claimed in claim 2 , wherein the electromagnetic shield is integral to the structure or dielectric system of the FCL.

6. The method as claimed in claim 2 , wherein the electromagnetic shield is incorporated into an otherwise non-magnetic or non-conductive material or structure.

7. The method as claimed in claim 2 , wherein the electromagnetic shield is incorporated into a composite tank including at least one of the mechanical structure and part of the dielectric system of a FCL.

8. The method as claimed in claim 2 , wherein the electromagnetic shield is separate from an otherwise non-magnetic or non-conductive material or structure.

9. The method as claimed in claim 2 , wherein the electromagnetic shield is separate from a composite tank including at least one of the mechanical structure and part of the dielectric system of a FCL.

10. The method as claimed in claim 1 , wherein the electromagnetic shield suppresses a first transient peak in the fault current waveform during a fault condition.

11. A fault current limiter, comprising:

first and second high permeability columns;

first phase coil wound around the second high permeability column;

an electrically conductive shield substantially encapsulating the phase coils; and

magnetic saturation unit surrounding the first and second high permeability columns for substantially saturating the columns during non fault operation,

wherein the phase coils and the permeability columns are arranged substantially adjacent and parallel to one another.

12. The limiter of claim 11 , wherein the first and second phase coils are wound around respective columns with an opposite helix pattern.

13. The limiter of claim 11 , wherein the phase coil and corresponding high permeability column are substantially concentric.

14. The limiter of claim 11 , wherein the first and second high permeability columns include a cross section having an elongated segment with said elongated segments being arranged in a substantially opposed manner.

15. The limiter of claim 11 , wherein the electrically conductive shield is formed from a metallic material.

16. The limiter of claim 11 , wherein the first and second phase coils are aligned and have their mid points in a common plane.

17. The limiter of claim 11 , wherein the first and second phase coils are adjacent one another and wound in an opposite sense.

18. In a fault current limiter of a saturated high permeability core type having at least one phase wound around a high permeability material, a method of suppressing a time derivative of a transient fault current during a zero current condition, comprising:

utilizing one of a screen or a shield around the phase coil to suppress a magnitude of di/dt at the zero current condition.