Sensor devices and methods for use in sensing current through a conductor

• US 9,081,040 B2
• Filed: 07/30/2014
• Issued: 07/14/2015
• Est. Priority Date: 09/09/2011
• Status: Active Grant

• Current Assignee: Aclara Meters LLC (Hubbell, Inc.)
• Original Assignee: General Electric Company
• Inventors: Chamarti, Subramanyam Satyasurya, Bietz, Steven Lee
• Primary Examiner(s): Koval, Melissa
• Assistant Examiner(s): MILLER, DANIEL R
• Application Number:
  US14/447,053
• Publication Number:
  US 20140340072A1
• Time in Patent Office: 349 Days
• US Class Current: 1/1
• CPC Class Codes: G01R 1/18 Screening arrangements against electric or magnetic fields, e.g. against earth's field
• CPC Class Codes: G01R 1/20 Modifications of basic electric elements for use in electric measuring instruments; Structural combinations of such elements with such instruments
• CPC Class Codes: G01R 15/181 using coils without a magnetic core, e.g. Rogowski coils
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G01R 21/00 Arrangements for measuring electric power or power factor G01R7/12 takes precedence
• CPC Class Codes: G01R 22/06 by electronic methods
• CPC Class Codes: G01R 3/00 Apparatus or processes specially adapted for the manufacture or maintenance of measuring instruments , e.g. of probe tips
• CPC Class Codes: G01R 35/005 Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references G01R33/0035, G01R35/002 take precedence
• CPC Class Codes: Y10T 29/49071 by winding or coiling

Abstract

A utility meter and related methods are disclosed. The utility meter includes a sensor device positioned around a conductor to sense current flowing through the conductor. The sensor device includes a non-magnetic substrate, a coil comprising a plurality of turns wound about the substrate, and a dielectric material having a dielectric constant and positioned between the coil and the conductor. The utility meter also includes a meter control board in communication with the sensor device to determine an amount of electricity transmitted through the conductor from the power source to the user over time. The dielectric constant of the dielectric material is selected to reduce a capacitive coupling between the coil and the conductor and to reduce a sensitivity of the sensor device such that the meter control board comprises only one calibration coefficient for calibrating the sensor device over a current range.

Claims

1. A utility meter for use in transmitting electrical energy from a power source to a user, said utility meter comprising:

a sensor device positionable at least partially around a conductor to sense current flowing through said conductor and to output a signal representative of said sensed current, said sensor device comprising;

a non-magnetic substrate comprising a plurality of bobbins;

a coil comprising a plurality of turns wound about said substrate, said coil defining an aperture through which said conductor is to be received, wherein at least one of said plurality of turns is wound about each of said plurality of bobbins; and

a dielectric material having a dielectric constant and positioned adjacent to said coil and at least partially within said aperture such that said dielectric material is between said coil and said conductor when said conductor is received through said aperture; and

a meter control board in communication with said sensor device to receive said signal representative of said sensed current from said sensor device and to determine an amount of electricity transmitted through said conductor from the power source to the user over time;

wherein said dielectric constant of said dielectric material is selected to reduce a capacitive coupling between said coil and said conductor and to consequently reduce a sensitivity of said sensor device such that said meter control board comprises only one calibration coefficient for calibrating said sensor device over a current range.

2. The utility meter of claim 1, wherein said dielectric material comprises at least one of a thermoplastic material and a thermoset material.

3. The utility meter of claim 2, wherein said dielectric material comprises at least one of a polyethylene terephthalate (PET) material and a polybutylene terephthalate (PBT) thermoplastic material.

4. The utility meter of claim 1, further comprising a mount positioned at least partially within said aperture, said mount configured to support a conductor positioned in said aperture, and wherein said mount is fabricated at least partially from said dielectric material.

5. The utility meter of claim 4, further comprising an enclosure at least partially enclosing said substrate and said coil, said enclosure comprising said mount.

6. The utility meter of claim 1, wherein said dielectric material encloses at least a portion of said coil and at least a portion of said substrate.

7. The utility meter of claim 6, wherein the sensor device comprises said mount forming a friction fit with said conductor, wherein said mount defines at least one air-gap between said sensor device and said conductor, and wherein said mount comprises at least a portion of said dielectric material.

8. The utility meter of claim 1, wherein said sensor device is configured to sense current through said conductor within about ±

0.2% of an actual current through said conductor in a current range between of about 2.0 Amps to about 320 Amps.

9. The utility meter of claim 1, wherein said sensor device is configured to sense current through said conductor within about ±

0.5% of an actual current through said conductor in a current range between of about 2.0 Amps to about 25,000 Amps.

10. The utility meter of claim 7, wherein each of said plurality of bobbins comprise a thermoplastic material.

11. The utility meter of claim 10, wherein said conductor includes one of a bus bar and a multi-strand conductor.

12. The utility meter of claim 7, further comprising a second sensor device positionable at least partially around a second conductor and in communication with said meter control board.

13. The utility meter of claim 12, further comprising a third sensor device positionable at least partially around a third conductor and in communication with said meter control board.

14. The utility meter of claim 1, wherein said current range is about 2.0 A to about 25,000 A.

15. A method of fabricating a utility meter for use in transmitting electrical energy from a power source to a user, said method comprising:

providing a sensor device positionable at least partially around a conductor to sense current flowing through said conductor and to output a signal representative of said sensed current, wherein providing said sensor device comprises;

forming a coil comprising a plurality of turns wound about a non-magnetic substrate, said coil defining an aperture through which said conductor is to be received, wherein forming the coil includes winding at least one turn of the coil on each of a plurality of bobbins of the substrate;

positioning a dielectric material adjacent to said coil and at least partially within said aperture such that said dielectric material is between said coil and said conductor when said conductor is received through said aperture; and

connecting a meter control board with said sensor device to receive said signal representative of said sensed current from said sensor device and to determine an amount of electricity transmitted through said conductor from the power source to the user over time;

selecting said dielectric material such that a dielectric constant of said dielectric material reduces a capacitive coupling between said coil and said conductor and consequently reduces a sensitivity of said sensor device such that said meter control board comprises only one calibration coefficient for calibrating said sensor device over a current range.

16. The method of claim 15, wherein positioning the dielectric material adjacent to the coil includes at least partially enclosing the coil within an enclosure, said enclosure comprising the dielectric material.

17. The method of claim 15, further comprising configuring said sensor device to sense current through said conductor within about ±

0.2% of an actual current through said conductor in a current range between of about 2.0 Amps to about 320 Amps.

18. The method of claim 15, further comprising configuring said sensor device to sense current through said conductor within about ±

0.5% of an actual current through said conductor in a current range between of about 2.0 Amps to about 25,000 Amps.

19. The method of claim 15, further comprising:

positioning a second sensor device at least partially around a second conductor; and

positioning a third sensor device at least partially around a third conductor;

wherein said second sensor device and said third sensor device are connected with said meter control board.

20. The method of claim 15, wherein said current range is about 2.0 A to about 25,000 A.