Split Rogowski coil current measuring device and methods

• US 20080106254A1
• Filed: 11/06/2006
• Published: 05/08/2008
• Est. Priority Date: 11/06/2006
• Status: Active Grant

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Cooper Technologies Company (Eaton Corporation PLC.)
• Inventors: Kojovic, Ljubomir A.
• Granted Patent: US 7,538,541 B2
• Time in Patent Office: Days
• US Class Current: 324/127
• CPC Class Codes: G01R 15/181 using coils without a magnetic core, e.g. Rogowski coils
• CPC Class Codes: G01R 15/247 Details of the circuitry or construction of devices covered by G01R15/241 - G01R15/246
• CPC Class Codes: H01F 38/30 Constructions
• CPC Class Codes: H01F 5/003 Printed circuit coils

Abstract

A split Rogowski coil assembly having distinct coil loops formed on printed circuit boards that are not joined to one another.

Claims

1. A Rogowski coil assembly, comprising:

a first Rogowski coil portion comprising a first coil surrounding a first portion of a conductor and generating a first voltage output signal at a first location other than at the ends of the first coil;

a second Rogowski coil portion comprising a second coil adjacent to the first Rogowski coil portion and surrounding a second portion of the conductor and generating a second voltage output signal at a second location other than at the ends of the second coil,

wherein the first voltage output signal and the second voltage output signal are combined to provide a third output signal, the third output signal being processed to determine a current flowing through the conductor.

2. The Rogowski coil assembly of claim 1, wherein the third output signal is integrated to determine the current flowing through the conductor.

3. The Rogowski coil assembly of claim 1, wherein the first coil portion further comprises first and second printed circuit boards and the second coil portion further comprises third and fourth printed circuit boards,

wherein the first and second circuit boards comprise a first winding of the first coil and a second winding of the first coil connected in respective opposite directions;

and

wherein the third and fourth circuit boards comprise a third winding of the second coil and a fourth winding of the second coil connected in respective opposite directions.

4. The Rogowski coil assembly of claim 1, wherein the first coil portion and the second coil portion are separately provided and configured to be installed around the conductor without disconnecting the conductor.

24. The Rogowski coil assembly of claim 1, wherein the first and second Rogowski coil portions are substantially U-shaped.

25. The Rogowski coil assembly of claim 1, wherein the first Rogowski coil portion does not completely surround the conductor,

wherein the second Rogowski coil portion does not completely surround the conductor.

26. The Rogowski coil assembly of claim 3, wherein the first and second windings comprise a substantially continuous loop,

wherein the third and fourth windings comprise a substantially continuous loop.

5. A Rogowski coil assembly, comprising:

a first printed circuit board assembly comprising first and second circuit boards, the first circuit board having a first section of coil formed thereon and the second circuit board having a second section of coil formed thereon, the first and second sections of coil being connected in series with one another to form a larger continuous section of coil, the first and second circuit boards defining a first coil loop generating a first voltage output when placed around a conductor; and

a second printed circuit board assembly separately provided from the first printed circuit board assembly, the second printed circuit board assembly comprising third and fourth circuit boards, the third circuit board having a third section of coil formed thereon and the fourth circuit board having a fourth section of coil formed thereon, the third and fourth sections of coil being connected in series with one another to form a larger continuous section of coil, the third and fourth circuit boards defining a second coil loop generating a second voltage output when placed around the conductor,

wherein a total voltage output of the coil assembly is the sum of the first voltage output and the second voltage output.

6. The Rogowski coil assembly of claim 5, wherein the first and second circuit boards comprise coil sections that are wound in the same direction on each printed circuit board.

7. The Rogowski coil assembly of claim 5, wherein the third and fourth circuit boards comprise coil sections wound in opposite directions on each printed circuit board.

8. The Rogowski coil assembly of claim 5, wherein the first voltage output and the second voltage output are connected in series with one another to provide the total voltage output of the coil.

9. The Rogowski coil assembly of claim 5, wherein the first coil loop and the second coil loop are not joined.

27. The Rogowski coil assembly of claim 5, wherein the first voltage output and the second voltage output are measured at a location other than at ends of the respective coils.

28. The Rogowski coil assembly of claim 5, wherein the first and second pairs of circuit boards are substantially U-shaped.

10. A Rogowski coil system, comprising:

a conductor;

a Rogowski coil formed in at least a first portion and a second portion separately provided from one another and having unconnected coil loops in the respective portions, each of the portions generating a respective voltage output when an energized conductor is passed through the coil; and

a measuring device that combines a respective voltage output signal of the distinct coil portions,

wherein the first portion and the second portion are configured to be placed around the energized conductor without de-energizing the conductor.

11. The system of claim 10, wherein each of the coil loops are formed on a pair of printed circuit boards connected in series to one another.

12. The system of claim 10, further comprising a current calculating device that determines the current in the conductor using the combined voltage signals.

13. The Rogowski coil system of claim 10, wherein the combined voltage signal is integrated to determine the current flowing through the conductor.

14. The Rogowski coil assembly of claim 10, wherein the first and second portions each comprise a plurality of printed circuit boards having windings connected in opposite directions, the windings of the first and second portions being connected in series with one another.

15. A method of monitoring current with a Rogowski coil assembly, the method comprising:

providing a first Rogowski coil section forming a first portion of a Rogowski coil;

providing a second Rogowski coil section forming a second portion of the Rogowski coil;

positioning the first and second Rogowski coil sections about a conductor without directly connecting the first and second Rogowski coil sections to each other;

obtaining distinct voltage outputs from each of the first and second Rogowski coil sections at locations other than at the ends of the first and second coil sections; and

summing the voltage outputs of the first and second Rogowski coil sections.

16. The method of claim 15, further comprising integrating the summed voltage outputs to provide a signal corresponding to the current flowing in the conductor.

17. The method of claim 15, further comprising connecting the summed voltage output to a voltage measuring device.

18. A split Rogowski coil, comprising:

a separately provided first coil assembly and second coil assembly, each defining a distinct closed loop portion of the Rogowski coil when installed around a conductor, the current flowing through the conductor being proportional to the sum of the voltages generated in the first and second coil assemblies.

19. The split Rogowski coil of claim 18, wherein each of the first and second coil assemblies comprises a plurality of circuit boards comprising windings connected in opposite directions.

20. The split Rogowski coil of claim 18, wherein one of the first and second coil assemblies comprises a pair of circuit boards, and one of the circuit boards comprises coil sections wound in the same direction.

21. The split Rogowski coil of claim 18, wherein one of the first and second coil assemblies comprises a pair of circuit boards, and one of the circuit boards comprises coil sections wound in an opposite direction.

22. The split Rogowski coil of claim 18, further comprising interface cables connecting the first coil assembly and the second coil assembly in series.

23. The split Rogowski coil of claim 18, wherein the closed loop portions are not directly connected with one another in each of the first coil assembly and the second coil assembly.