Current measurement apparatus

• US 7,746,059 B2
• Filed: 03/29/2005
• Issued: 06/29/2010
• Est. Priority Date: 04/29/2004
• Status: Active Grant

• Current Assignee: Lem Heme Limited (LEM Holding SA)
• Original Assignee: Lem Heme Limited (LEM Holding SA)
• Inventors: Ebenezer, Desmond, Zwolinski, Albert
• Primary Examiner(s): Hollington; Jermele M
• Application Number:
  US10/599,843
• Publication Number:
  US 20070210787A1
• Time in Patent Office: 1,918 Days
• Field of Search: None
• US Class Current: 324/127
• CPC Class Codes: G01R 15/181 using coils without a magnetic core, e.g. Rogowski coils

Abstract

The current measurement apparatus comprises a Rogowski coil 20 comprising a wire or conductor which forms a coil 22 and returns through the coil 22 as a central conductor. The coil 22 and the central conductor are formed from a single conductor or wire and, therefore, no electrical join (for example, a solder join or crimp) is required at the end of the Rogowski coil. The wire 28 used to form the coil 22 and the central conductor 24 is insulated prior to forming the Rogowski coil. The insulated coating 30 provides better insulation between individual coils and also helps to provide a more even spacing between the coils.

Claims

1. Current measurement apparatus comprising a Rogowski coil wherein the Rogowski coil comprises a seamless conductive member, wherein the conductive member by itself is seamless, said single conductive member forms a coil and a central conductor extending through the coil wherein said conductive member forms single homogeneous wire and said homogeneous wire is insulated prior to forming the Rogowski coil.

2. Current measurement apparatus according to claim 1 in which the wire is insulated by insulating material.

3. Current measurement apparatus according to claim 2 in which the insulating material is resistant to physical damage.

4. Current measurement apparatus according to claim 2 in which the complete outer surface of the wire is coated with an insulating material.

5. Current measurement apparatus according to claim 4 in which the complete outer surface of the wire is coated with an insulating material which provides reinforced insulation.

6. Current measurement apparatus according to claim 2 in which the insulating material comprises a wrapping for the wire.

7. Current measurement apparatus according to claim 2 in which the insulating material is an extrusion.

8. Current measurement apparatus according to claim 1 in which the insulation coating is less than or equal to 0.125 mm.

9. Current measurement apparatus according to claim 1 in which the Rogowski coil is formed by providing a straight central conductor section and winding a coil around at least a part of the straight electrical conductor section.

10. Current measurement apparatus according to claim 1 in which the Rogowski coil comprises an inner sheath.

11. Current measurement apparatus according to claim 1 in which the wire comprises copper wire.

12. Current measurement apparatus according to claim 1 in which the Rogowski coil comprises an end wherein the end does not require an insulation cap.

13. Current measurement apparatus according to claim 1 in which the wire comprises a plurality of layers of insulating material.

14. Current measurement apparatus according to claim 1 in which the Rogowski coil comprises a first end and a second end.

15. Current measurement apparatus according to claim 14 in which, in use, the first end is arranged, in use, to locate adjacent to the second end.

16. Current measurement apparatus according to claim 14 in which, a first end member located on the first end is arranged, in use, to engage a second end member located on the second end.

17. Current measurement apparatus according to claim 1 in which a first end member located on one end of the Rogowski coil is arranged, in use, to cooperate with a second end member located on a second end of the Rogowski coil.

18. Current measurement apparatus according to claim 1 in which, in use, a first end of the Rogowski coil is arranged, in use, to cooperate with a second end member located on the second end of the Rogowski coil in order to form a contiguous loop.

19. Current measurement apparatus according to claim 1 in which a first end of the Rogowski coil is arranged to magnetically cooperate with a second end of the Rogowski coil.

20. Current measurement apparatus according to claim 16 in which the first end member comprises a female member and the second end member comprises a male member.

21. Current measurement apparatus according to claim 16 in which the first end member is arranged, in use, to be secured to the second end member solely by magnetic force.

22. A method of forming current measurement apparatus comprising forming a Rogowski coil from a seamless conductive member, wherein the conductive member by itself is seamless;

forming said seamless conductive member into a coil and a central conductor extending through the coil;

insulating said seamless conductive member before forming said coil and central conductor.

23. A Rogowski coil having a seamless conductive member, wherein said conductive member by itself is seamless, said seamless conductive member forms a coil and a central conductor extending through a center of the coil, and the seamless conductive element is insulated.