WHOLE STRUCTURE CONTACTLESS POWER CONSUMPTION SENSING

• US 20110074382A1
• Filed: 09/25/2009
• Published: 03/31/2011
• Est. Priority Date: 09/25/2009
• Status: Active Grant

• Current Assignee: University of Washington
• Original Assignee: University of Washington
• Inventors: Patel, Shwetak
• Granted Patent: US 8,930,152 B2
• Time in Patent Office: Days
• US Class Current: 324/76.11
• CPC Class Codes: G01R 15/207 Constructional details independent of the type of device used
• CPC Class Codes: G01R 21/001 Measuring real or reactive component; Measuring apparent energy G01R21/01, G01R21/02, G01R21/08, G01R21/10 and G01R21/127 take precedence
• CPC Class Codes: G01R 21/06 by measuring current and voltage G01R21/08 - G01R21/133 take precedence
• CPC Class Codes: G01R 22/063 related to remote communication
• 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

Abstract

A contactless current and power consumption sensor can be safely mounted on a circuit breaker box of a structure, so as to sense the current flow and/or power consumed in the structure. Because the sensor can be mounted on a surface of the circuit breaker box without the need to access energized conductors inside the box, an unskilled person can readily install the sensor to monitor total instantaneous current flow and thus, determine the power consumed by energized devices in the structure on a continuing basis. The output from the sensor can be supplied to a readout or can be conveyed by a wired or wireless link to a computing device disposed at a remote location, where the data can be stored or viewed on a display. By integrating the power consumed over time, the energy usage by the energized devices in a structure can also be determined.

Claims

1. A method for contactless sensing of electrical current flow supplying electrical power to a structure, comprising the steps of:

(a) affixing a current sensor to a position on a surface of a panel that overlies main electrical lines supplying electrical power to the structure, preventing personnel from contacting the main electrical lines and other energized conductors that are covered by the panel;

(b) sensing electrical current flowing in the main electrical lines with the current sensor, producing an output signal that is indicative of said current; and

(c) processing the output signal to determine the electrical current flowing in the main electrical lines.

2. The method of claim 1, further comprising the step of displaying a magnitude of the electrical current flowing in the main electrical lines.

3. The method of claim 1, further comprising the step of conveying an indication of the electrical current flowing in the main electrical lines to a location that is spaced apart from the current sensor.

4. The method of claim 3, wherein the step of conveying comprises the step of conveying by either a wire conductor link or a wireless link.

5. The method of claim 1, further comprising the steps of:

(a) sensing a voltage on at least one of the main electrical lines; and

(b) automatically computing a power level for the electrical load in the structure, as a function of a product of the voltage that was sensed and the electrical current that was determined.

6. The method of claim 5, further comprising the step of computing a reactive power for electrical current flowing through the electrical load in the structure, wherein the electrical load is not purely resistive.

7. The method of claim 6, further comprising the step of determining a phase difference between the electrical current flowing in the main electrical lines and the voltage.

8. The method of claim 5, displaying the power computed for the electrical load in the structure, wherein the power that is displayed is at least one of a true power, a reactive power, and an apparent power.

9. The method of claim 5, further comprising the step of integrating the power that was computed over a time interval to determine a total energy consumed by the load in the structure during the time interval.

10. The method of claim 9, further comprising the steps of:

(a) storing a value for the total energy consumed during at least one time interval; and

(b) conveying a value for the total energy consumed during at least one time interval to an entity that determines a payment due for the energy supplied to the structure during said at least one time interval.

11. The method of claim 1, further comprising the step of calibrating the current sensor by selectively energizing a known load for a period of time, while monitoring an indication of the current flowing based on the output signal of the current sensor.

12. The method of claim 1, wherein the step of sensing electrical current flowing in the main electrical lines with the current sensor comprises the step of employing a current sensor selected from the group of current sensors consisting of:

(a) a magnetoresistive current sensor;

(b) a Hall effect current sensor;

(c) a fluxgate sensor; and

(d) an induction coil.

13. The method of claim 1, wherein the step of sensing electrical current flowing in the main electrical lines with the current sensor comprises the step of employing a current sensor that includes a plurality of sensing elements, including a sensing element overlying each main electrical line.

14. The method of claim 1, wherein the surface of the panel comprises a surface of an electrical circuit breaker panel, and wherein the step of affixing the current sensor to the position on the surface of the panel comprises the step of removably attaching the current sensor to the surface of the electrical circuit breaker panel.

15. A system for monitoring a parameter related to electrical power use in a structure, comprising:

(a) a contactless electrical current sensor that is configured to be attached to a surface of a panel at a position overlying electrical main lines supplying electrical power to a structure, without removing the panel to expose the main electrical lines and other energized conductors that are covered by the panel, the electrical current sensor sensing an electrical current flowing through the main electrical lines and producing an output signal that is indicative of said current; and

(b) a processing circuit that receives the output signal and processes the output signal to determine the parameter that is related to electrical power use.

16. The system of claim 15, further comprising a display for displaying a magnitude of the parameter related to electrical power use.

17. The system of claim 15, further comprising a wireless transmitter for conveying an indication of the parameter to a location that is spaced apart from the contactless current sensor.

18. The system of claim 15, further comprising a wire link for conveying an indication of the parameter to a location that is spaced apart from the contactless current sensor.

19. The system of claim 15, further comprising a line cord and conventional line plug for connecting the processing circuit to a conventional electrical line socket, to provide a connection to enable the processing circuit to detect a voltage on at least one electrical line in the structure.

20. The system of claim 19, wherein the parameter comprises a magnitude of either the electrical current flowing through the electrical main lines to energize an electrical load in the structure, or a power consumed by the electrical load, wherein the power is determined by the processing circuit as a function of a product of the electrical current and the electrical line voltage.

21. The system of claim 19, where the processing circuit determines a phase difference between the electrical current flowing in at least one of the main electrical lines and voltage on the line.

22. The system of claim 21, wherein the parameter determined by the processing circuit comprises a reactive power for an electrical load in the structure, if the electrical load is not purely resistive.

23. The system of claim 19, wherein the processing circuit integrates the power supplied over a time interval to determine a total electrical energy supplied to the electrical load during the time interval.

24. The system of claim 23, further comprising a non-volatile memory for storing values for the total energy supplied during at least one time interval, for use in billing for the electrical energy supplied.

25. The system of claim 15, further comprising a calibration load that is configured to be coupled to at least one of the electrical lines in the structure, while monitoring the parameter, so that the processing circuit can be calibrated to accurately determine the parameter based on an effect of the calibration load on the output signal from the contactless current sensor.

26. The system of claim 15, wherein the contactless current sensor comprises a sensor selected from the group of sensors consisting of:

(a) a magnetoresistive current sensor;

(b) a Hall effect current sensor;

(c) a fluxgate sensor; and

(d) an induction coil.

27. The system of claim 15, wherein the contactless current sensor includes a plurality of sensing elements that are configured to enable positioning a sensing element on a surface over each main electrical line.

28. The system of claim 15, wherein the contactless current sensor includes an adhesive backing to enable the contactless current sensor to be removably attached to a surface of an electrical circuit breaker panel.

29. The system of claim 15, wherein the processing circuit determines a plurality of different parameters related to electrical power use in the structure, further comprising a switch enabling a user to select a specific parameter to display.