Shielded Rogowski coil assembly and methods

• US 7,564,233 B2
• Filed: 11/06/2006
• Issued: 07/21/2009
• 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:
  US11/593,239
• Publication Number:
  US 20080106253A1
• Time in Patent Office: 988 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

Shielded Rogowski coil systems having separate interface cables and methods for eliminating and monitoring noise in signal transmissions over the cables. An embodiment of a Rogowksi coil system includes a first Rogowski coil surrounding a conductor and generating a first voltage output signal, and a second Rogowski coil surrounding the conductor and generating a second voltage signal, wherein the first voltage output signal and the second voltage output signal are processed to address noise components in the output signals. An exemplary method of eliminating and monitoring current with a Rogowski coil includes providing first and second Rogowski coils, connecting an interface conductor to each coil, obtaining distinct voltage outputs from each coil, and applying a noise effect algorithm to the voltage outputs.

Claims

1. A Rogowski coil assembly, comprising:

a first Rogowski coil comprising a first printed circuit board and a first conductive winding thereon, the first Rogowski coil surrounding a conductor and generating a first voltage output signal proportional to a rate of change of current flowing through the conductor;

a second Rogowski coil comprising a second printed circuit board and a second conductive winding thereon, the second coil surrounding the conductor and generating a second voltage output signal proportional to the rate of change of current flowing through the conductor;

a pair of interface cables, each of the pair of interface cables being coupled to one of the first and second Rogowski coils at an end of the conductive winding thereof, each of the interface cables transmitting one of the first and second voltage output signals; and

at least one magnetic shield disposed around a termination of at least one of the interface cables, at an end of its corresponding conductive winding, the at least one magnetic shield being configured to prevent voltages from being induced in the interface cables at the terminations thereof.

2. The Rogowski coil assembly of claim 1, wherein the first and second Rogowski coils extend in opposite directions.

3. The Rogowski coil assembly of claim 1, wherein each termination of the first and second interface cables is separately magnetically shielded to prevent voltages from being induced in the interface cables at the termination locations.

4. The Rogowski coil assembly of claim 1, wherein the first and second interface cables are surrounded by a common magnetic shield.

5. The Rogowski coil assembly of claim 1, wherein at least one of the first and second interface cables comprises a coaxial cable.

6. The Rogowski coil assembly of claim 1, at least one of the interface cables comprising a twisted pair wire.

7. The Rogowski coil assembly of claim 1, wherein the first and second interface cables are connected in series.

8. The Rogowski coil assembly of claim 1, further comprising a microprocessor based device connected to each of the first and second interface cables, the microprocessor based device programmed to determine a level of noise in the first and second output voltage signals.

9. The Rogowski coil assembly of claim 1, further comprising a microprocessor based device connected to each of the first and second interface cables, the microprocessor based device programmed to cancel noise in the first and second output voltage signals.

10. A Rogowski coil system, comprising:

a conductor;

a first Rogowski coil comprising a conductive circuit board and a right handed coil formed thereon, the right handed coil receiving the conductor and generating a first voltage output when the conductor is energized;

a second Rogowski coil comprising a conductive circuit board and a left handed coil formed thereon, the left-handed coil receiving the conductor and generating a generating a second voltage output when the conductor is energized;

a first interface cable terminated to the first Rogowski coil;

a second interface cable separately provided form the first interface cable, each of the interface conductors transmitting one of the first and second voltage output signals; and

at least one magnetic shield, each magnetic shield disposed around a termination of at least one of the interface cables, at an end of its corresponding conductive winding, the at least one magnetic shield being configured to prevent voltages from being induced in the interface cables at the terminations thereof.

11. The Rogowski coil assembly of claim 10, wherein the Rogowski coil assembly comprises a pair of magnetic shields, each termination of the first and second interface cables being separately magnetically shielded by one of the magnetic shields.

12. The Rogowski coil assembly of claim 10, wherein the first and second interface cables are surrounded by a common magnetic shield.

13. The Rogowski coil assembly of claim 10, wherein each of the interface coils comprises at least one of a coaxial cable and a twisted pair wire.

14. The Rogowski coil assembly of claim 10, wherein the first and second interface cables are connected in series.

15. The Rogowski coil assembly of claim 10, further comprising a microprocessor based device connected to each of the first and second interface cables, the microprocessor based device programmed to determine a level of noise in the first and second output voltage signals.

16. The Rogowski coil assembly of claim 10, further comprising a microprocessor based device connected to each of the first and second interface cables, the microprocessor based device programmed to cancel noise in the first and second output voltage signals.