SYSTEMS AND DEVICES FOR REDUCING PHANTOM LOAD

• US 20110127854A1
• Filed: 12/01/2010
• Published: 06/02/2011
• Est. Priority Date: 12/01/2009
• Status: Active Grant

• Current Assignee: International Electrical Savings & Development, LLC
• Original Assignee: International Electrical Savings & Development, LLC
• Inventors: Brunning, Daniel B., Cruz, Paul M., McKenzie, Thomas J.
• Granted Patent: US 8,664,804 B2
• Time in Patent Office: Days
• US Class Current: 307/131
• CPC Class Codes: H01H 47/007 with galvanic isolation between controlling and controlled circuit, e.g. transformer relay
• CPC Class Codes: H01H 9/54 Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere
• CPC Class Codes: H02J 9/005 using a power saving mode for copiers G03G15/5004
• CPC Class Codes: H02J 9/007 Detection of the absence of a load

Abstract

Systems and devices are described herein for reducing a phantom load. The system may include a device for connection to a power source and a transformer or machine, wherein the device is configured to disconnect the transformer or machine from the power source under a predetermined load condition. The device may include a contactor, a current detector, a timer, and a controller. Portions of the current detector, timer, or controller may be implemented in a microcontroller.

Claims

1. A system for reducing phantom load in a device, wherein the device receives three or more phases of alternating current from an electrical power source, the system comprising:

outputs configured to provide electric power obtained at least in part from the three or more phases of alternating current;

a power supply configured for electrical connection to the electrical power source, wherein the power supply is configured to transform at least one or more phases of the alternating current into a plurality of direct current voltages;

a contactor configured for electrical connection to each phase of the alternating current and for electrical connection to inputs of the device, wherein the contactor is configured to selectively connect each of the phases to a respective input of the device, wherein the outputs are in electrical communication with the contactor;

a current detector configured for electrical communication with the outputs, the current detector comprising

a plurality of current sensors, at least one of the plurality of current sensors being associated with each of the phases provided by the outputs,

a summer configured to sum the current sensed in each of the current sensors,

a comparator configured to compare the summed current to a predetermined value, the comparator being configured to generate a first signal when the summed current is less than the predetermined value;

a timer in communication with the comparator and configured to indicate that a predetermined amount of time has elapsed; and

a controller configured to receive the first signal from the comparator and the indication from the timer, and configured to cause the contactor to disconnect each phase of alternating current of the power source from the inputs of the device based on at least the first signal and the indication.

2. The system of claim 1, wherein the controller is configured to disconnect each phase of alternating current when the summed current is below the predetermined value for a period of time greater than or equal to the predetermined amount of time.

3. The system of claim 1, wherein the comparator is configured to generate a second signal when the summed current is greater than or equal to the predetermined value.

4. The system of claim 1, further comprising an enable unit in communication with an input device, wherein the enable unit is configured to notify the controller of a user input on the input device, and wherein the controller is configured to cause the contactor to connect each phase of alternating current of the power source to the inputs of the device in response to being notified.

5. The system of claim 4, wherein the controller is configured to disconnect each phase of alternating current when the predetermined amount of time has elapsed since the enable unit notified the controller and the summed current is below the predetermined value for a period.

6. The system of claim 4, wherein the enable unit comprises a transmitter configured to wirelessly notify the controller of the user input.

7. The system of claim 4, wherein the controller is configured to wait for at least a first delay after the contactor has been opened before connecting each phase of alternating power.

8. The system of claim 1, wherein the power supply is configured to supply one or more of the plurality of direct current voltages to the current detector, the timer, and the controller.

9. The system of claim 1, wherein the timer is configured to allow selection of the predetermined amount of time.

10. The system of claim 1, further comprising a mechanism configured to drive the contactor in response to commands from the controller, and further configured to galvanically isolate the controller from the power source.

11. The system of claim 10, wherein the contactor is a normally-open contactor, and wherein the mechanism is configured to apply a current to the contactor sufficient to keep the contactor closed when the summed current is at least as great as the predetermined value.

12. The system of claim 1, wherein one or more of the current sensors comprises a sensing coil encircling a conductor carrying the phase that the sensor is associated with.

13. The system of claim 1, further comprising a selector configured to change when the timer begins counting down the predetermined amount of time.

14. The system of claim 1, wherein the device comprises an industrial machine, and wherein an input of the industrial machine is coupled to one of the outputs.

15. The system of claim 1, wherein the device comprises a transformer, wherein a primary winding of the transformer is coupled to the contactor, and wherein a secondary winding of the transformer is coupled one of the outputs.

16. An apparatus for automatically disconnecting a device from a power source, the power source providing two or more phases of current, the device comprising:

two or more outputs, each of the outputs corresponding to a respective phase of the two or more phases of current;

a switch electrically configured for electrical connection to the power source and to inputs of the device, wherein the switch is configured to selectively connect the two or more phases of current to the inputs of the device;

at least two current sensors configured to sense current flowing to the outputs;

a comparator configured to detect when the total current sensed in the at least two current sensors is below a threshold; and

a determination unit in communication with the switch and configured to determine, based at least on the detection of the comparator, when to disconnect the two or more phases of current from the inputs of the device.

17. The apparatus of claim 16, wherein the comparator is configured to detect when the combined current is below the threshold.

18. The apparatus of claim 16, further comprising a timer in communication with the determination unit and the comparator, wherein the determination unit determines to disconnect the two or more phases of current from the transformer when the current sensed in the at least two current sensors is below the threshold and the timer indicates that a selected time has expired.

19. The apparatus of claim 18, wherein the selected time begins when the switch is placed into a closed configuration.

20. The apparatus of claim 18, wherein the selected time begins when the sensed current dips below the threshold and resets each time the sensed current rises above the threshold.

21. The apparatus of claim 18, wherein the timer is configured to start counting the selected time based on a user input.

22. The apparatus of claim 18, further comprising a timer input, wherein the selected time is set by a user of the device using the timer input.

23. The apparatus of claim 16, wherein the switch is configured to remain open except when receiving a current above a predetermined actuation level, and further comprising a triac configured to lower a current being supplied to the switch to a level below the predetermined actuation level when the determination unit determines to disconnect the two or more phases of current from the inputs of the device.

24. The apparatus of claim 16, wherein at least one of the comparator and the determination unit comprises a microcontroller.

25. The apparatus of claim 24, wherein the microcontroller is configured to calculate a running root mean square value of current sensed in at least one of the current sensors.

26. The apparatus of claim 16, further comprising a metal oxide varistor configured to isolate the comparator and the determination unit from transients generated in the switch.

27. The apparatus of claim 16, further comprising an interface configured to provide information regarding the current sensed in the at least two current sensors to a display.

28. A device, comprising:

means for sensing total current drawn by an apparatus from a power source;

means for indicating that a selected amount of time has expired;

means for determining when the total current drawn by the apparatus is less than a threshold and the selected amount of time has expired; and

means for electrically disconnecting the power source from the device based at least in part on the determination of the determining means.

29. The device of claim 28, wherein the means for determining comprises means for detecting when the total current is below the threshold.

30. The device of claim 29, wherein the means for determining comprises means for determining that the selected amount of time has elapsed since an enablement command was received.

31. The device of claim 29, wherein the means for determining comprises means for determining that the selected amount of time has elapsed since the current was detected as being below the threshold.

32. The device of claim 28, further comprising means for enabling, wherein activating the enabling means causes the disconnecting means to cease disconnecting the device from the power source.

33. The device of claim 32, wherein the sensing means comprises a current sensor associated with each of two or more phases of the power source, wherein the sensing means further comprises a summing amplifier in combination with a potentiometer, wherein the gain of the amplifier is adjustable by a user.

34. A method of reducing a phantom load, comprising:

coupling a power source to an input of an apparatus;

coupling a device to an output of the apparatus;

attaching a current sensor around a conductor of the output, wherein the apparatus comprises

a switch coupled to the input, the switch being configured to selectively connect the input to the output,

a comparator configured to detect when current sensed in the current sensor is below a threshold, and

a determination unit in communication with the switch and configured to determine, based at least on the detection of the comparator, when to disconnect the input from the output; and

adjusting a parameter of the determination unit such that current drawn by the device when the device is active is above the threshold, and such that current drawn by the device when the device is idle is below the threshold.

35. The method of claim 34, wherein the determination unit comprises a potentiometer in combination with an amplifier configured to amplify the sensed current, and wherein adjusting the parameter comprises calibrating the amplifier by adjusting the potentiometer.