Rogowski coil assembly and methods

• US 7,902,812 B2
• Filed: 06/02/2009
• Issued: 03/08/2011
• 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.
• Primary Examiner(s): Hollington; Jermele M
• Application Number:
  US12/476,501
• Publication Number:
  US 20090230948A1
• Time in Patent Office: 644 Days
• Field of Search: None
• US Class Current: 324/117.00R
• 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 27/36 Electric or magnetic shields or screens movable for varying inductance H01F21/10
• CPC Class Codes: H01F 27/366 made of ferromagnetic material
• CPC Class Codes: H01F 38/30 Constructions
• CPC Class Codes: H01F 5/003 Printed circuit coils

Abstract

A Rogowski coil assembly includes a first Rogowski coil that surrounds a conductor and generates a first voltage output signal. A second Rogowski coil also surrounds the conductor. The second Rogowski coil generates a second voltage output signal. A relay device communicates with the first and second Rogowski coils and processes the first and second voltage output signals. For example, the relay device can process the voltage output signals to calculate an amount of noise in the first and second output voltage signals and/or to minimize the amount of noise in the first and second output voltage signals.

Claims

1. A Rogowski coil assembly, comprising:

a first Rogowski coil surrounding a conductor and generating a first voltage output signal;

a second Rogowski coil surrounding the conductor and generating a second voltage output signal; and

a relay device interfaced with the first and second Rogowski coils and programmed to process the first voltage output signal and the second voltage output signal to calculate a level of noise in the first and second output voltage signals, wherein the relay device is further programmed to process the first output signal and the second voltage output signal to minimize the level of noise in the first and second output voltage signals.

2. The Rogowski coil assembly of claim 1, wherein each of the first Rogowski coil and the second Rogowski coil is fabricated on a printed circuit board.

3. The Rogowski coil assembly of claim 1, wherein the first and second Rogowski coils are electrically connected in opposite directions.

4. The Rogowski coil assembly of claim 1, further comprising first and second interface cables, each of the first and second interface cables being coupled to one of the first and second coils, each of the first and second interface cables being terminated to its respective coil at one end thereof, each termination of the first and second interface cables being separately magnetically shielded to prevent voltages from being induced in the interface cables at the terminations.

5. The Rogowski coil assembly of claim 1, further comprising first and second interface cables, each of the first and second interface cables being coupled to one of the first and second coils, the first and second interface cables being surrounded by a common magnetic shield.

6. The Rogowski coil assembly of claim 1, further comprising first and second interface cables, each of the first and second interface cables being coupled to one of the first and second coils, at least one of the cables comprising a coaxial cable.

7. The Rogowski coil assembly of claim 1, further comprising first and second interface cables for the respective first and second coils, at least one of the cables comprising a twisted pair wire.

8. The Rogowski coil assembly of claim 1, further comprising first and second interface cables for the respective first and second coils, the interface cables being connected in series.

9. The Rogowski coil assembly of claim 1, further comprising first and second interface cables coupling the respective first and second coils to the relay device.

10. A Rogowski coil assembly, comprising:

a first Rogowski coil surrounding a conductor and generating a first voltage output signal;

a second Rogowski coil surrounding the conductor and generating a second voltage output signal; and

a relay device interfaced with the first and second Rogowski coils and programmed to process the first voltage output signal and the second voltage output signal to minimize an amount of noise in the first and second output voltage signals.

11. The Rogowski coil assembly of claim 10, wherein the relay device is further programmed to process the first output signal and the second voltage output signal to calculate the amount of noise in the first and second output voltage signals.

12. The Rogowski coil assembly of claim 10, wherein each of the first Rogowski coil and the second Rogowski coil is fabricated on a printed circuit board.

13. The Rogowski coil assembly of claim 10, wherein the first and second Rogowski coils are electrically connected in opposite directions.

14. The Rogowski coil assembly of claim 10, further comprising first and second interface cables, each of the first and second interface cables being coupled to one of the first and second coils, each of the first and second interface cables being terminated to its respective coil at one end thereof, each termination of the first and second interface cables being separately magnetically shielded to prevent voltages from being induced in the interface cables at the terminations.

15. The Rogowski coil assembly of claim 11, further comprising first and second interface cables, each of the first and second interface cables being coupled to one of the first and second coils, the first and second interface cables being surrounded by a common magnetic shield.

16. The Rogowski coil assembly of claim 10, further comprising first and second interface cables, each of the first and second interface cables being coupled to one of the first and second coils, at least one of the cables comprising a coaxial cable.

17. The Rogowski coil assembly of claim 10, further comprising first and second interface cables for the respective first and second coils, at least one of the cables comprising a twisted pair wire.

18. The Rogowski coil assembly of claim 10, further comprising first and second interface cables for the respective first and second coils, the interface cables being connected in series.

19. The Rogowski coil assembly of claim 10, further comprising first and second interface cables coupling the respective first and second coils to the relay device.

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

providing a first Rogowski coil comprising a first winding;

providing a second Rogowski coil comprising a second winding extending opposite to the first winding;

connecting an interface cable to each of the first and second Rogowski coils;

obtaining distinct voltage outputs from each of the first and second Rogowski coils, via the interface cables; and

minimizing an amount of noise in the voltage outputs by using a microprocessor based device to apply a noise effect algorithm to the voltage outputs.