Non-intrusive monitoring of power and other parameters

• US 8,907,664 B2
• Filed: 11/28/2012
• Issued: 12/09/2014
• Est. Priority Date: 11/06/2009
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Leeb, Steven B., Clifford, Zachary A., Cooley, John J., Avestruz, Al-Thaddeus
• Primary Examiner(s): Aurora, Reena
• Application Number:
  US13/687,336
• Publication Number:
  US 20130141088A1
• Time in Patent Office: 741 Days
• Field of Search: 324/228, 324/522, 324/76.11
• US Class Current: 324/228
• CPC Class Codes: G01R 31/3277 of low voltage devices, e.g. domestic or industrial devices, such as motor protections, relays, rotation switches
• CPC Class Codes: G01R 33/12 Measuring magnetic properties of articles or specimens of solids or fluids involving magnetic resonance G01R33/20

Abstract

Methods and apparatus for non-intrusive power monitoring and current measurement in a circuit breaker without modification of the breaker panel or the circuit breaker itself. In one example, an inductive pickup sensor senses current from the breaker face, an inductive link transmits power through a steel breaker panel door, and a passive balanced JFET modulator circuit modulates a carrier signal on the inductive link with information regarding the sensed current. A demodulated breaker current signal is available outside of the breaker panel door. The JFET modulator circuit does not require DC power to modulate the carrier signal with the information regarding the sensed current from the breaker. Such methods and apparatus may be interfaced with a spectral envelope load detection system that can monitor multiple loads from a central location.

Claims

1. A system for monitoring a circuit breaker of a circuit breaker unit, the circuit breaker unit comprising a ferromagnetic material separating an interior of the circuit breaker unit from an exterior of the circuit breaker unit, the system comprising:

a field sensor configured to sense a field in a proximity of the circuit breaker; and

a coupler configured to transmit a signal from the interior of the circuit breaker unit such that the signal passes through the ferromagnetic material to the exterior of the circuit breaker unit, wherein the signal represents the field sensed by the field sensor.

2. The system of claim 1, wherein the ferromagnetic material comprises steel.

3. The system of claim 1, wherein the circuit breaker unit comprises a door, and the door comprises the ferromagnetic material.

4. The system of claim 1, wherein the field sensor comprises a magnetic field sensor configured to sense a magnetic field produced by a current-carrying conductor of the circuit breaker.

5. The system of claim 1, wherein the coupler is configured to receive a carrier signal.

6. The system of claim 5, further comprising:

a mixer configured to modulate a sensed signal from the field sensor with the carrier signal to produce a modulated signal, wherein the coupler is configured to transmit the modulated signal to the exterior of the circuit breaker unit, wherein the modulated signal is the signal that represents the field sensed by the field sensor.

7. The system of claim 1, further comprising an attachment apparatus configured to secure the field sensor to a face of the circuit breaker.

8. The system of claim 1, wherein the coupler comprises a coil.

9. The system of claim 8, wherein the coupler is a first coupler and the system further comprises a second coupler comprising a second coil.

10. The system of claim 9, wherein the first coupler is positioned on a first side of the ferromagnetic material and the second coupler is positioned on a second side of the ferromagnetic material.

11. The system of claim 1, further comprising a magnet to at least partially saturate magnetic domains in the ferromagnetic material.

12. The system of claim 1, wherein the system is configured to be retrofit to the circuit breaker to perform non-intrusive monitoring of the circuit breaker.