Self testing fault circuit apparatus and method

• US 8,547,126 B2
• Filed: 07/29/2010
• Issued: 10/01/2013
• Est. Priority Date: 01/29/2008
• Status: Active Grant

• Current Assignee: Leviton Manufacturing Company Incorporated
• Original Assignee: Leviton Manufacturing Company Incorporated
• Inventors: Ostrovsky, Michael, Kevelos, Adam
• Primary Examiner(s): Hollington, Jermele M
• Application Number:
  US12/845,924
• Publication Number:
  US 20100295568A1
• Time in Patent Office: 1,160 Days
• Field of Search: None
• US Class Current: 324/750.3
• CPC Class Codes: G01R 31/2884 using dedicated test connectors, test elements or test circuits on the IC under test G01R31/2855 takes precedence
• 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: H02H 3/335 the main function being self testing of the device

Abstract

A self testing fault circuit interrupter device comprising a fault circuit comprising at least one line monitoring circuit, at least one line interrupting circuit and at least one fault detector circuit which is configured to selectively operate said at least one line interrupting circuit when a fault is detected. This fault circuit also includes at least one test circuit configured to initiate a self test on the fault circuit and at least one timing circuit for controlling the time period for a self test being performed on said at least one self test circuit. The timing circuitry can be in the form of external circuitry which comprises a transistor which controls the discharge rate of a timing capacitor. The timing capacitor is present to prevent any false triggering of a fault circuit. A fault circuit test condition does not stop until the capacitor is fully discharged. By controlling the timing capacitor discharge rate, the triggering of an SCR is not delayed too much in the presence of an external fault because during the presence of this external fault the test cycle is considerably shortened in time based directly upon the size of the external fault. The testing circuit can include a microcontroller which can be programmed to perform a self test across at least two different half cycles of opposite polarity. The determination of the timing of the self test is based upon timing performed by the microcontroller in combination with zero crossing circuitry.

Claims

1. A self testing fault circuit interrupter device comprising:

a) a fault circuit comprising;

i) at least one line monitoring circuit;

ii) at least one line interrupting circuit comprising contacts;

iii) at least one fault detector circuit which is configured to selectively operate said at least one line interrupting circuit when a fault is detected from said at least one line monitoring circuit;

b) at least one self test circuit including at least one microcontroller, said at least one self-test circuit configured to conduct a self test on said fault circuit;

c) at least one timing circuit configured to control a duration of an output of said fault detector circuit;

d) at least one contact detector circuit to detect whether said contacts are in an open or closed state; and

e) a first LED coupled to said at least one microcontroller and a second LED coupled to said at least one contact detector circuit.

3. The device as in claim 1 or 2, wherein said at least one self test circuit further comprises at least one transistor coupled to an output of said at least one microcontroller.

4. The device as in claim 1 or 2, wherein said at least one fault detector circuit comprises an integrated circuit.

5. The device as in claim 1 or 2, wherein said fault detector circuit further comprises at least one capacitor, wherein said timing circuit is configured to control a discharge rate of said capacitor.

6. The device as in claim 1 or 2, wherein said at least one fault detector circuit is an integrating fault detector circuit.

7. The device as in claim 5, wherein said timing circuit comprises at least one transistor, configured to selectively increase the discharge rate of said capacitor.

8. The device as in claim 7, wherein said timing circuit further comprises at least one resistor, wherein the resistance level of said resistor controls the rate of discharge of said capacitor.

9. The device as in claim 7, wherein said timing circuit is controlled by said at least one microcontroller.

12. The device as in claim 1 or 2, further comprising zero crossing circuitry in communication with said at least one microcontroller, wherein said at least one microcontroller in combination with said zero crossing circuitry forms said line monitoring circuit which is configured to sense an output of said zero crossing circuitry to determine an over voltage condition or an under voltage condition.

13. The device as in claim 1 or 2, wherein said at least one self test circuit is configured to provide a simulated fault signal during at least a portion of a first half cycle and during at least a portion of a second half cycle of opposite polarity.

17. The device as in claim 1 or 2, wherein said at least one fault detection circuit comprises an integrated circuit, wherein said microcontroller is configured to conduct the self test during at least a portion of a positive half cycle and during at least a portion of a negative half cycle of AC current.

18. The device as in claim 1 or 2, wherein said at least one line monitoring circuit comprises at least one sensor.

19. The device as in claim 1 or 2, further comprising:

a line side coupled to a set of building wiring, providing power to the device;

a load side coupled to a downstream load,

a plurality of selectively separable contacts configured to electrically connect/disconnect said line side from said load side;

wherein said microcontroller is configured to actuate said line interrupting circuit.

20. The self testing fault circuit interrupter device as in claim 12, wherein a level of said over voltage or under voltage is determined based on a slope of the zero crossing output.

21. The self testing fault circuit interrupter device as in claim 20, wherein said microcontroller upon determining an over voltage or under voltage condition is configured to perform at least one of the following tasks:

indicate an over voltage or under voltage condition and actuate the at least one line interrupting circuit.

23. The device as in claim 1 or 2, wherein said at least one timing circuit is further configured to control a time period of the self test, and to shorten the time period for the self test in the presence of an actual fault.

24. The device as in claim 1 or 2, wherein said at least one line interrupting circuit is selectively activated by said at least one self test circuit when said at least one self test circuit determines that there is a failed self test condition.

2. A self testing fault circuit interrupter device comprising:

a) a fault circuit comprising;

i) at least one line monitoring circuit;

ii) at least one line interrupting circuit comprising contacts;

iii) at least one fault detector circuit which is configured to selectively operate said at least one line interrupting circuit when a fault is detected from said at least one line monitoring circuit;

b) at least one self test circuit including at least one microcontroller, said at least one self-test circuit configured to conduct a self test on said fault circuit;

c) at least one timing circuit configured to control a duration of an output of said fault detector circuit; and

d) at least one indicator circuit for communicating a result of a self test,

wherein said indicator circuit is configured to indicate at least one of the following states;

i) a first indication state indicating that either no power is provided to said fault circuit, and said self test circuit, or that a line and load wiring configuration has been reversed;

ii) a second indication state indicating that there is no power provided to said self test circuit, and that at least one contact of said contacts has tripped;

iii) a third indication state indicating that there is power provided to the device, that the self test has passed, and that at least one contact is latched;

iv) a fourth indication state indicating that there is power provided to the device, that the self test has passed, and that at least one contact is open;

v) a fifth indication state indicating that said self test has failed, and indicating that at least one contact did not open successfully; and

vi) a sixth indication state indicating that said self test has failed and that at least one contact has opened.

10. The device as in claim 2, wherein said at least one indicator circuit is selected from the group consisting of an audible annunciator, a visible indicator, and a communication circuit.

11. The device as in claim 10, wherein said visible indicator comprises at least one LED configured to display at least one self-test result.

22. The self testing fault circuit interrupter device as in claim 11 wherein said at least one LED comprises a plurality of LEDs and wherein said display of said at least one self test result comprises at least one of:

all of said plurality of LEDS off, at least one LED of said plurality of LEDs on, at least two of said plurality of LEDs on all LEDs on, and at least one LED blinking.

14. A self testing fault circuit interrupter device comprising:

a) a fault circuit comprising;

i) at least one line monitoring circuit;

ii) at least one line interrupting circuit comprising contacts;

iii) at least one fault detector circuit which is configured to selectively operate said at least one line interrupting circuit when a fault is detected from said at least one line monitoring circuit;

b) at least one self test circuit including a microcontroller, said at least one self-test circuit configured to conduct a self test on said fault circuit;

c) at least one timing circuit configured to control a duration of an output of said fault detector circuit; and

d) at least one overcurrent detector,

wherein said microcontroller is configured to perform at least one of the following steps;

activating said at least one line interrupting circuit when said microcontroller determines an overcurrent condition; and

indicating an overcurrent condition when said microcontroller determines an overcurrent condition.

15. A self testing fault circuit interrupter device comprising:

a) a fault circuit comprising;

i) at least one line monitoring circuit;

ii) at least one line interrupting circuit comprising contacts;

iii) at least one fault detector circuit which is configured to selectively operate said at least one line interrupting circuit when a fault is detected from said at least one line monitoring circuit;

b) at least one self test circuit including a microcontroller, said at least one self-test circuit configured to conduct a self test on said fault circuit;

c) at least one timing circuit configured to control a duration of an output of said fault detector circuit; and

d) at least one temperature sensor coupled to said microcontroller,

wherein said microcontroller is configured to activate said at least one line interrupting circuit when said microcontroller determines a temperature has crossed a preset threshold point.

16. A self testing fault circuit interrupter device comprising:

a) a fault circuit comprising;

i) at least one line monitoring circuit;

ii) at least one line interrupting circuit comprising contacts;

iii) at least one fault detector circuit which is configured to selectively operate said at least one line interrupting circuit when a fault is detected from said at least one line monitoring circuit;

b) at least one self test circuit including a microcontroller, said at least one self-test circuit configured to conduct a self test on said fault circuit;

c) at least one timing circuit configured to control a duration of an output of said fault detector circuit; and

d) at least one fuse coupled to said microcontroller, and to at least one of a phase line or a neutral line, wherein said microcontroller is configured to selectively open a path on said phase line or said neutral line by actuating said fuse.