PROCESSOR-BASED CIRCUIT INTERRUPTING DEVICES

• US 20140092503A1
• Filed: 10/01/2012
• Published: 04/03/2014
• Est. Priority Date: 10/01/2012
• Status: Active Grant

• Current Assignee: Leviton Manufacturing Company Incorporated
• Original Assignee: Leviton Manufacturing Company Incorporated
• Inventors: Ostrovsky, Michael
• Granted Patent: US 9,276,393 B2
• Time in Patent Office: Days
• US Class Current: 361/45
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 3/044 Checking correct functioning of protective arrangements, e.g. by simulating a fault for differential current circuit breakers H02H3/335
• CPC Class Codes: H02H 3/20 responsive to excess voltage
• CPC Class Codes: H02H 3/335 the main function being self testing of the device
• CPC Class Codes: H02H 3/338 also responsive to wiring error, e.g. loss of neutral, break

Abstract

Circuit interrupting devices are provided. One circuit interrupting device includes a fault sensor configured to output a sensor signal; a voltage sensor configured to sense a reference voltage; and a controller configured to determine an occurrence of an actual fault based on the sensor signal and the reference voltage. The circuit interrupting device further includes an amplifier configured to receive the sensor signal and the reference voltage and output an amplified signal; an analog-to-digital converter configured to receive the reference voltage and the amplified signal and output respective digital signals corresponding to the reference voltage and the amplified signal; and a line interrupt assembly configured to interrupt current flow through a conductive path when a characteristic of the sensor signal exceeds an actual fault threshold.

Claims

1. A fault circuit interrupting device comprising:

a fault sensor configured to output a sensor signal;

a voltage sensor configured to sense a reference voltage; and

a controller configured to determine an occurrence of an actual fault based on the sensor signal and the reference voltage;

2. The fault circuit interrupting device according to claim 1, further comprising an amplifier configured to receive the sensor signal and the reference voltage and output an amplified signal.

3. The fault circuit interrupting device according to claim 2, further comprising:

an analog-to-digital converter configured to receive the reference voltage and the amplified signal and output respective digital signals corresponding to the reference voltage and the amplified signal; and

a line interrupt assembly configured to interrupt current flow through a conductive path when a characteristic of the sensor signal exceeds an actual fault threshold.

4. The fault circuit interrupting device according to claim 1, wherein the controller is selected from the group consisting of a microcontroller, a system on chip (SOC), and a field programmable gate array.

5. The fault circuit interrupting device according to claim 1, wherein the controller is further configured to determine whether the reference voltage exceeds a voltage threshold in determining the occurrence of the actual fault.

6. The fault circuit interrupting device according to claim 2, wherein the amplifier amplifies the characteristic of the sensor signal in accordance with a gain, and wherein the amplified signal has a frequency identical to a frequency of the sensor signal.

7. The fault circuit interrupting device according to claim 6, further comprising a gain circuit, wherein, based on the frequency of the sensor signal, the gain circuit adjusts the gain accordingly.

8. The fault circuit interrupting device according to claim 7, wherein the gain is adjusted to a first adjusted gain when the sensor signal has a first frequency, and wherein the gain is adjusted to a second adjusted gain when the sensor signal has a second frequency.

9. The fault circuit interrupting device according to claim 1, further comprising a self-test circuit configured to automatically initiate a self-test.

10. The fault circuit interrupting device according to claim 9, wherein the self-test includes circuitry configured to generate a simulated fault for testing operation of said system.

11. The fault circuit interrupting device according to claim 1, further comprising a manual test assembly comprising a test button configured to initiate a test.

12. The fault circuit interrupting device according to claim 11, wherein the test is configured to interrupt a conductive path and generate a simulated fault.

13. The fault circuit interrupting device according to claim 1, further comprising an arc fault sensor configured to output an arc sensor signal, indicative of an arc fault condition, to the controller, wherein the controller is configured to trigger a line interrupt assembly when the arc sensor signal exceeds an arc fault threshold.

14. The fault circuit interrupting device according to claim 1, further comprising a resistor connected across a first and a second conductor via which the sensor signal is output from the fault sensor for avoiding saturation of the fault sensor.

15. The fault circuit interrupting device according to claim 1, wherein the fault sensor includes a differential transformer, and wherein the fault circuit interrupting device further comprises a grounded neutral transformer configured to output a signal if a neutral conductor is grounded.

16. The fault circuit interrupting device according to claim 2, further comprising a test circuit configured to generate a simulated electrical fault condition, wherein the controller is configured to initiate a test operation including triggering the test circuit to generate the simulated fault condition, determine whether a characteristic of the amplified signal exceeds a test fault threshold during performance of the test operation without triggering a line interrupt assembly unless a characteristic of the amplified signal exceeds an actual fault threshold, and indicate the occurrence of a test failure when the test operation terminates and the determination is false, wherein the line interrupt assembly interrupts current flow through a conductive path when the characteristic of the amplified signal exceeds the actual fault threshold.

17. The fault circuit interrupting device according to claim 2, further comprising a memory unit, wherein the controller is configured to execute an algorithm for calculating a gain of the amplifier, the algorithm including at least one constant that influences the determination of the gain, the at least one constant being stored in the memory unit, and the controller is further configured to adjust the at least one constant for adjusting the calculation of the gain during a calibration procedure.

18. The fault circuit interrupting device according to claim 2, further comprising a memory unit, wherein the controller is further configured to determine an expected value for a characteristic of the amplified signal during a test operation in which the value of the characteristic of the amplified signal is approximately known, determine the value for the characteristic of the amplified signal as measured during the test operation, determine a difference between the approximately known value for the characteristic of the amplified signal and the determined value for the characteristic of the amplified signal, store the difference as an offset compensation constant in the memory unit, and apply the offset compensation constant in subsequent determinations of the value of the characteristic of the amplified signal.

19. The fault circuit interrupting device according to claim 2, wherein the controller comprises a compensation module for determining when the amplifier is saturated and, based on determining the amplifier is saturated, adjusts a value of a characteristic of the amplified signal.

20. The fault circuit interrupting device according to claim 2, wherein the controller is further configured to iteratively sample a characteristic of the amplified signal, and calculate an integrated value for the characteristic of the amplified signal iteratively, including executing an integration algorithm using the sampled values for the characteristic of the amplified signal.

21. The fault circuit interrupting device according to claim 1, further comprising a voltage regulator having a linear regulator component, wherein the controller is further configured to control the linear regulator component.

22. The fault circuit interrupting device according to claim 21, wherein the linear regulator component includes a variable resistor and the controller controls the resistance of the variable resistor.

23. The fault circuit interrupting device according to claim 1, wherein the controller is further configured to monitor a voltage input to a voltage regulator for detecting when a bridge diode fails to conduct current.

24. The fault circuit interrupting device according to claim 1, wherein the controller is further configured to perform at least one diagnostic test to check at least one component of the fault circuit interrupting device.

25. The fault circuit interrupting device according to claim 1, further comprising a sensor configured to sense an environmental parameter and provide an output signal indicative of the environmental parameter.

26. The fault circuit interrupting device according to claim 25, wherein the controller is further configured to adjust at least one software component of the fault circuit interrupting device in accordance with the output signal indicative of the environmental parameter.

27. The fault circuit interrupting device according to claim 25, wherein the environmental parameter is one selected from the group consisting of humidity and temperature.

28. The fault circuit interrupting device according to claim 25, wherein the sensor is located internally within said fault circuit interrupting device, located externally of said fault circuit interrupting device, and/or integrated with said controller.

29. The fault circuit interrupting device according to claim 1, wherein the controller is further configured to interrupt current flow to a conductor if the occurrence of an actual fault is determined.

30. The fault circuit interrupting device according to claim 1, wherein the controller is further configured to determine an RMS value of the sensor signal.

31. The circuit interrupting device according to claim 1, wherein the fault circuit interrupting device is selected from the group consisting of a GFCI system, an AFCI system, and a GFCI/AFCI system.

33. The fault circuit interrupting device according to claim 31, wherein the fault circuit interrupting device is selected from the group consisting of a GFCI system, an AFCI system, and a GFCI/AFCI system.

32. A fault circuit interrupting device comprising:

a fault circuit interrupting circuit for interrupting current flow through a conductive path after detection of a fault condition;

a voltage regulator in operative communication with the fault interrupting circuit and configured to receive a voltage; and

a controller configured to monitor the voltage for detecting failure of a diode of a bridge rectifier.

34. A fault circuit interrupting device comprising:

a first sensor configured to output a first signal having a first frequency and a first characteristic;

a second sensor positioned in proximity to the first sensor;

a gain circuit including a frequency dependent component configured to adjust a gain based on the frequency of the first signal such that when the first signal has a first frequency, the gain is adjusted to a first adjusted gain, and when the first signal has a second frequency, the gain is adjusted to a second adjusted gain that is different than the first adjusted gain;

an amplifier configured to receive the first signal and amplify the first characteristic in accordance with either the first or second adjusted gain, and outputting a corresponding amplified signal having a second characteristic and the same frequency as the first signal;

a line interrupt assembly configured to interrupt flow of current through a conductor when triggered; and

a controller configured to trigger the line interrupt assembly when the second characteristic exceeds an actual fault threshold.

35. The fault circuit interrupting device according to claim 34, further comprising an arc fault circuit interrupter (AFCI) circuit that outputs an arc signal indicative of an arc fault condition to the controller, wherein the controller is configured to trigger the line interrupt assembly when the arc signal provided by the AFCI circuit exceeds an arc fault threshold.

36. The fault circuit interrupting device according to claim 34, wherein the first sensor is a differential transformer, the electrical fault is a ground fault, and the second sensor is a grounded neutral transformer.

37. The fault circuit interrupting device according to claim 34, further comprising a reference voltage circuit configured to receive a voltage signal from a power source and output a corresponding reference signal having a reference voltage,

wherein the amplifier is configured to further receive the reference signal;

and

the controller is further configured to receive a digitized value corresponding to the reference voltage and trigger the line interrupt assembly when the second characteristic of the amplified signal exceeds the actual fault threshold and the received voltage value for the reference voltage does not exceed a noise threshold.

38. The fault circuit interrupting device according to claim 34, further comprising a self-test assembly configured to automatically initiate a self-test.

39. The fault circuit interrupting device according to claim 38, wherein the self-test includes generating a simulated fault for testing operation of said system.

40. The fault circuit interrupting device according to claim 34, further comprising a manual test assembly comprising a test button configured to initiate a test.

41. The fault circuit interrupting device according to claim 39, wherein the test includes opening at least one contact in electrical communication with the conductor and generating a simulated fault.

42. A method for monitoring a circuit for an electrical fault condition, the method comprising:

receiving a voltage signal and generating a reference voltage signal;

digitizing the reference voltage signal using an analog-to-digital converter and generating a digital signal corresponding to the reference voltage signal; and

processing the digital signal corresponding to the reference voltage signal and a sensor signal outputted from a transformer for determining the occurrence of an electrical fault condition.

43. The method according to claim 42, further comprising interrupting delivery of current to a load if occurrence of the electrical fault condition is determined.

44. A circuit interrupting device comprising:

a sensing device in operative communication with a solenoid, the sensing device configured for sensing an electrical fault condition and generating a signal in response to the sensed electrical fault condition for moving the solenoid, the electrical fault condition associated with current flowing through a conductor electrically coupled to a power source which generates a current output;

an amplifier configured for receiving the signal and generating an amplified signal;

a test circuit configured to generate a simulated fault condition along the conductor;

a line interrupt assembly configured to interrupt current flow through the conductor; and

a controller configured to control the test circuit for initiating a test operation which includes triggering the test circuit to generate the simulated fault condition, wherein the test operation terminates after a predetermined time interval, and wherein the predetermined time interval is less than a time required to trigger the line interrupt assembly after occurrence of an actual fault.

45. The circuit interrupting device according to claim 44, wherein the simulated fault condition includes a test signal, and wherein an amplitude of the test signal is less than an amplitude of the signal generated during the actual fault.

46. The circuit interrupting device according to claim 44, wherein the conductor is a first conductor, the system further comprising a second conductor, wherein the simulated fault condition includes generating an imbalance in currents passing through the first and second conductors.

47. The circuit interrupting device according to claim 46, wherein the imbalance includes adding a supplemental current to at least one of the first and second conductors, wherein the supplemental current is not synchronized with the current output by the power source.

48. The circuit interrupting device according to claim 47, wherein the supplemental current is generated through a substantial portion of two half cycles associated with the current output by the power source.

49. The circuit interrupting device according to claim 48, wherein the two half cycles are successive half cycles.