Intelligent ground fault circuit interrupter employing miswiring detection and user testing

• US 6,052,265 A
• Filed: 11/20/1998
• Issued: 04/18/2000
• Est. Priority Date: 11/20/1998
• Status: Expired due to Term

• Current Assignee: Leviton Manufacturing Company Incorporated
• Original Assignee: Leviton Manufacturing Company Incorporated
• Inventors: Bradley, Roger M., Zaretsky, Albert
• Primary Examiner(s): SHERRY, MICHAEL JUDE
• Application Number:
  US09/197,192
• Time in Patent Office: 515 Days
• Field of Search: 361/42, 361/45, 361/46, 361/78, 361/87, 361/93.4, 340/635, 340/638, 340/650, 340/654, 340/664
• US Class Current: 361/42
• 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

An intelligent ground fault circuit interrupter device that incorporates a test and miswiring control circuit in addition to an independent GFCI circuit. Since the test and miswiring circuit is separate and independent of the GFCI circuit portion, it can be used with any circuit interrupting means that can be reset and which incorporates a test circuit. The test and miswiring circuit functions to indicate to a user when the device must be manually tested. The test time events occur upon first installation and on a monthly basis thereafter. The device also indicates that testing is required after occasions of power outage of sufficient time duration and after the device has been tripped by the occurrence of a ground fault. At the times when manual testing of the device is required, a visual and/or audible alarm is triggered and continues until a successful test and reset sequence is completed. The ability to detect when the device is incorrectly wired in an electrical wiring system is also provided. Upon detection of a miswiring condition, a visual and/or audible alarm is triggered to alert the user to the miswired condition. The alarm cannot be disabled unless the miswiring condition is removed.

Claims

1. The method of determining the status of an intelligent circuit interrupting device, comprising the steps of:

a) producing a first signal indicative of the status of a test button;

b) producing a second signal indicative of the status of a line line;

c) producing a third signal indicative of the status of a load line; and

d) sampling periodically one of said first, second and third signals and based upon such sampling indicating the status of an intelligent circuit interrupting device.

2. The method as defined in claim 1, wherein said first signal can indicate that contacts of said test button are open or closed.

3. The method, as defined in claim 1, wherein said first signal can be of a first potential to indicate that the contacts of said test button are open or of a second potential to indicate that contacts of said test button are closed.

4. The method, as defined in claim 3, wherein

a) said second signal can be of said first potential or of said second potential;

and

b) said third signal can be of said first potential or of said second potential.

5. The method, as defined in claim 1, wherein said sampling of said first, second and third signals is performed on the negative edge of every complete cycle of a 60 HzAC cycle of a test input.

6. The method, as defined in claim 4, wherein said sampling of said first, second and third signals is performed on the negative edge of every complete cycle of a 60 HzAC cycle of a test input.

7. The method, as defined in claim 4, wherein any change in a potential of said first, second or third signals is verified over a number of 60 HzAC cycles before new first, second or third signals are used to determine the status of an intelligent circuit interrupting device.

8. The method, as defined in claim 6, wherein any change in a potential of said first, second or third signals is verified over a number of 60 HzAC cycles before new first, second or third signals are used to determine the status of an intelligent circuit interrupting device.

9. The method, as defined in claim 4, wherein when said first, second and third signals are at said second potential they indicate that said test button of said intelligent circuit interrupting device has been pushed to close its contacts.

10. The method, as defined in claim 9, wherein said first signal must be at said second potential in more than 20 samples out of 32 test cycles to verify that said test button contacts are closed.

11. The method, as defined in claim 4, wherein when said first and second signals are at said first potential and said third signal is at said second potential they indicate that relay contacts of said intelligent circuit interrupting device are open.

12. The method, as defined in claim 11, wherein said third signal must be at said second potential for less than 6 samples out of 32 test cycles to verify that said relay contacts are open.

13. The method, as defined in claim 7, wherein when said first signal is at said first potential and said second and third signals are at said second potential they indicate that relay contacts of said intelligent circuit interrupting device are closed.

14. The method, as defined in claim 13, wherein said third signal must be at said second potential for more than 20 samples out of 32 test cycles to verify that said relay contacts are closed.

15. The method, as defined in claim 7, wherein when said first and third signals are at said first potential and said second signal is at said second potential they indicate that said relay contacts of said intelligent circuit interrupter device are open and said device is miswired with respect to a line and a load to which it is coupled.

16. The method, as defined in claim 15, wherein second signal must be at said second potential for less than 6 samples out of 32 test cycles to verify that said relay contacts are open and said device is miswired.

17. The method, as defined in claim 7, wherein when said first and second signals are at said second potential and said third signal is at said first potential they indicate that relay contacts of said intelligent circuit interrupter device are open and said device is miswired with respect to a line and a load to which it is coupled.

18. The method, as defined in claim 17, wherein said second signal must be at said second potential for less than 6 samples out of 32 test cycles to verify that said relay contacts are open and said device is miswired.