Magnetic shield for current transformer in electronic watt-hour meter

• US 8,664,935 B2
• Filed: 11/24/2010
• Issued: 03/04/2014
• Est. Priority Date: 11/24/2010
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Shaw, Bradley Douglas, Ingram, Dwight Wayne
• Primary Examiner(s): Hollington, Jermele M
• Assistant Examiner(s): NGUYEN, TRUNG Q
• Application Number:
  US12/953,713
• Publication Number:
  US 20120126787A1
• Time in Patent Office: 1,196 Days
• Field of Search: None
• US Class Current: 324/110
• 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

Abstract

An electronic watt-hour meter; a current transformer operatively coupled to the electronic watt-hour meter; a first shield on a first side of the current transformer; and a second shield on a second side of the current transformer, wherein the second side is substantially parallel to the first side, wherein the first shield and the second shield each include a substantially magnetically permeable and conductive metal.

Claims

1. An electronic watt-hour meter, comprising:

a current transformer operatively coupled to the electronic watt-hour meter;

a first shield on a first side of the current transformer; and

a second shield on a second side of the current transformer, wherein the second side is substantially parallel to the first side,

wherein the first shield and the second shield each include a substantially disc shaped body;

an aperture through approximately a center of the body; and

a gap in the body, the gap extending from an edge of the body to the aperture and a substantially magnetically permeable and conductive metal, and wherein the aperture accommodates a potential link through the current transformer.

2. The electronic watt-hour meter of claim 1, wherein the substantially magnetically permeable and conductive metal includes a low carbon steel.

3. The electronic watt-hour meter of claim 2, wherein the low carbon steel includes less than approximately 0.26 percent carbon content.

4. The electronic watt-hour meter of claim 1, wherein the current transformer is substantially torodial in shape.

5. The electronic watt-hour meter of claim 1, wherein one of the first shield and the second shield is thicker than the other of the first shield and the second shield.

6. The electronic watt-hour meter of claim 1, wherein at least one of the first shield and the second shield substantially shields up to approximately 5000 gauss from an external magnet.

7. An electronic watt-hour meter, comprising:

a current transformer operatively coupled to the electronic watt-hour meter;

a first shield on a first side of the current transformer;

a second shield on a second side of the current transformer, wherein the second side is substantially parallel to the first side;

wherein at least one of the first shield and the second shield substantially shields up to approximately 5000 gauss from an external magnet and

wherein the first shield and the second shield each include a substantially disc shaped body;

an aperture through approximately a center of the body; and

a gap in the body, the gap extending from an edge of the body to the aperture and a substantially magnetically permeable and conductive metal, and wherein the aperture accommodates a potential link through the current transformer.