Method and apparatus for testing an AFCI/GFCI circuit breaker

• US 6,426,632 B1
• Filed: 04/28/2000
• Issued: 07/30/2002
• Est. Priority Date: 03/29/1999
• Status: Expired due to Fees

• Current Assignee: GSK Technologies Incorporated
• Original Assignee: George A. Spencer
• Inventors: Clunn, Robert Henry
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): Deb, Anjan K
• Application Number:
  US09/561,400
• Time in Patent Office: 823 Days
• Field of Search: 324/509, 324/424, 324/127, 324/158.1, 361/42, 703/18
• US Class Current: 324/509
• CPC Class Codes: G01R 15/183 using transformers with a magnetic core
• CPC Class Codes: G01R 31/3274 Details related to measuring, e.g. sensing, displaying or computing; Measuring of variables related to the contact pieces, e.g. wear, position or resistance measuring contact resistance G01R27/205
• CPC Class Codes: H02H 1/0007 concerning the detecting means in general G01R or other subclasses of G01; reed switches H01H71/2445
• CPC Class Codes: H02H 1/0038 concerning the connection of the detecting means, e.g. for reducing their number
• CPC Class Codes: H02H 3/334 with means to produce an artificial unbalance for other protection or monitoring reasons or remote control H02H3/338 takes precedence

Abstract

There is disclosed and claimed herein apparatus and a method for testing an electronic circuit breaker having separable contacts and arc fault and/or ground fault interrupting capability responsive to differential currents in the line and neutral conductors, wherein the circuit breaker under test is connected in a test circuit, comprising the steps of: supplying operating power to the source terminals of the circuit breaker wherein the test circuit provides for connecting the neutral conductor source terminal to a ground in the test circuit; coupling testing signals from a test generator in the test circuit to the neutral conductor load terminal of the circuit breaker; and monitoring the condition of the separable contacts in the circuit breaker during the supply of testing signals to the neutral conductor load terminal. In one aspect, the test generator is operated under program control to provide a testing signal sequence to the neutral conductor load terminal of the circuit breaker, which sequence may include a command signal for setting a precondition in the circuit breaker prior to applying testing signals to the circuit breaker under test.

Claims

1. A method for testing an electronically activated circuit breaker having source and load terminals and separable contacts disposed in the line and neutral conductors of the power line and further having arc fault and/or ground fault interrupting capability responsive to differential currents in the line and neutral conductors wherein the circuit breaker under test is connected in a test circuit, comprising the steps of:

supplying operating power to the source terminals of the circuit breaker wherein the test circuit provides for connecting the neutral conductor source terminal to a ground in the test circuit;

coupling testing signals from a test generator in the test circuit to the neutral conductor load terminal of the circuit breaker; and

monitoring the condition of the separable contacts in the circuit breaker following the supplying of testing signals to the neutral conductor load terminal.

2. The method of claim 1, further comprising the step of:

operating the test generator under programmed control to provide a testing signal sequence to the neutral conductor load terminal of the circuit breaker.

3. The method of claim 2, further comprising the step of:

providing a testing signal having command signal data followed by test waveform data.

4. The method of claim 2, further comprising the step of:

providing a testing signal having a sequence of test waveform data.

5. The method of claim 4, wherein the step of providing comprises the step of:

associating a must-trip criterion with a first test waveform in the sequence; and

associating a must-not trip criterion with a second test waveform in the sequence.

6. The method of claim 5, wherein the step of providing comprises the step of:

associating the must-trip criterion with the first test waveform.

7. The method of claim 5, wherein the step of providing comprises the step of:

associating the must-not trip criterion with the first test waveform.

8. The method of claim 4, wherein the step of providing comprises the step of:

associating a must-trip criterion with each test waveform in the sequence of test waveforms.

9. The method of claim 4, wherein the step of providing comprises the step of:

associating a must-not criterion with each test waveform in the sequence of test waveforms.

10. The method of claim 1, wherein the step of coupling testing signals comprises the step of:

generating the testing signals from a library of digitized test waveforms.

11. The method of claim 10, wherein the step of generating the testing signals comprises the steps of:

selecting a test sequence;

generating a testing command; and

assembling the testing signal comprising the test sequence following the testing command.

12. The method of claim 11, wherein the step of selecting a test sequence comprises the step of:

specifying which test waveforms from the library are to be addressed and retrieved.

13. The method of claim 11, wherein the step of generating a testing command comprises the steps of:

determining whether preconditioning of the circuit breaker under test is required; and

configuring the testing command to perform the required preconditioning of the circuit breaker under test.

14. The method of claim 13, wherein the step of configuring the testing command comprises the step of:

disabling a ground detection circuit if one is present in the circuit breaker being tested.

15. The method of claim 11, wherein the step of assembling the testing signal comprises the step of:

coupling a testing command signal from a low current source together with a test waveform signal from a high current source to a summing point for sending to the neutral conductor load terminal.

16. A method for testing an electronically activated circuit breaker having source and load terminals and separable contacts disposed in the line and neutral conductors of the power line and further having arc fault and/or ground fault interrupting capability responsive to differential currents in the line and neutral conductors wherein the circuit breaker under test is connected in a test circuit, comprising the steps of:

supplying operating power to the source terminals of the circuit breaker wherein the test circuit provides for connecting the neutral conductor source terminal to a ground in the test circuit;

coupling a test generator in the test circuit to the neutral conductor load terminal of the circuit breaker;

operating the test generator under programmed control to provide a testing signal sequence to the neutral conductor load terminal of the circuit breaker; and

monitoring the condition of the separable contacts in the circuit breaker following the supplying of testing signals to the neutral conductor load terminal.

17. The method of claim 16, further comprising the step of:

providing a testing signal having command signal data followed by test waveform data.

18. The method of claim 16, further comprising the step of:

providing a testing signal having a sequence of test waveform data.

19. The method of claim 18, wherein the step of providing comprises the step of:

associating a must-trip criterion with a first test waveform in the sequence; and

associating a must-not trip criterion with a second test waveform in the sequence.

20. The method of claim 19, wherein the step of providing comprises the step of:

associating the must-trip criterion with the first test waveform.

21. The method of claim 19, wherein the step of providing comprises the step of:

associating the must-not trip criterion with the first test waveform.

22. The method of claim 18, wherein the step of providing comprises the step of:

associating a must-trip criterion with each test waveform in the sequence of test waveforms.

23. The method of claim 18, wherein the step of providing comprises the step of:

associating a must-not trip criterion with each test waveform in the sequence of test waveforms.

24. The method of claim 16, wherein the step of operating the test generator comprises the steps of:

selecting a test sequence;

generating a testing command for insertion in the test sequence preceding the first test waveform; and

sending the completed testing signal sequence to the neutral conductor load terminal of the circuit breaker under test.

25. The method of claim 24, wherein the step of selecting a test sequence comprises the steps of:

specifying which test waveforms from a library of digitized waveforms are to be addressed and retrieved.

26. The method of claim 24, wherein the step of generating a testing command comprises the steps of:

determining whether preconditioning of the circuit breaker under test is required; and

configuring the testing command to perform the required preconditioning of the circuit breaker under test.

27. The method of claim 24, wherein the step of sending comprises the step of:

coupling a testing command signal from a low current source together with a test waveform signal from a high current source to a summing point for sending to the neutral conductor load terminal.

28. The method of claim 26, wherein the step of configuring the testing command comprises the step of:

generating a logic level one comprising a sine wave burst of specified duration and a logic level zero comprising the absence of a sine wave burst of the specified duration.

29. The method of claim 16, wherein the step of monitoring comprises the steps of:

comparing the voltage at the neutral conductor load terminal with a reference; and

indicating the result of the monitoring step.

30. The method of claim 16, wherein the step of monitoring comprises the steps of:

determining whether the neutral conductor load terminal is grounded; and

indicating the result of the monitoring step.