Fail-safe electronic circuit breaker

• US 6,472,882 B1
• Filed: 10/23/2000
• Issued: 10/29/2002
• Est. Priority Date: 10/23/2000
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: General Electric Company
• Inventors: Tiemann, Jerome Johnson, Baertsch, Richard Dudley
• Primary Examiner(s): Le, N.
• Assistant Examiner(s): KERVEROS, DEMETRIOS C
• Application Number:
  US09/693,171
• Time in Patent Office: 736 Days
• Field of Search: 324/424, 324/508, 324/509, 361/42, 361/104, 361/45, 361/48
• US Class Current: 324/509
• 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: H01H 2083/201 the other abnormal electrical condition being an arc fault
• CPC Class Codes: H01H 2083/206 with thermal shunt trip
• CPC Class Codes: H01H 71/04 Means for indicating condition of the switching device by means of an auxiliary contact H01H71/46
• CPC Class Codes: H01H 71/123 using a solid-state trip unit circuits H02H
• CPC Class Codes: H01H 71/20 with fusible mass
• CPC Class Codes: H02H 3/335 the main function being self testing of the device

Abstract

The fail-safe electronic circuit breaker includes a test circuit connected to a fault detection circuit. The test circuit selectively generates a simulated circuit fault that is supplied to the fault detection circuit. The fail-safe electronic circuit breaker also includes a trip mechanism disabler that is connected to the test circuit. The trip mechanism disabler permanently disables the fail-safe electronic circuit breaker when the fault detection circuit fails to detect the simulated circuit fault after about a predetermined amount of time.

Claims

1. A fail-safe electronic circuit breaker comprising:

a fault detection circuit for detecting a circuit fault;

a test circuit connected to the fault detection circuit, the test circuit selectively generating a simulated circuit fault;

a trip mechanism connected to the fault detection circuit and the test circuit, the trip mechanism tripping the fail-safe electronic circuit breaker when the circuit fault is detected by the fault detection circuit; and

a trip mechanism disabler connected to the trip mechanism and the test circuit, the trip mechanism disabler permanently disabling the trip mechanism when the fault detection circuit fails to detect the simulated circuit fault after about a predetermined amount of time.

2. The fail-safe electronic circuit breaker of claim 1 wherein the trip mechanism disabler comprises:

a test-error mechanism connected to the test circuit, the test-error mechanism having at least a first position and a second position wherein the test-error mechanism irreversibly enters the second position when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time.

3. The fail-safe electronic circuit breaker of claim 1 wherein the trip mechanism comprises a trip lever connected to the fault detection circuit for tripping the fail-safe electronic circuit breaker when a circuit fault is detected by the fault detection circuit;

and

the trip mechanism disabler comprises a test-error mechanism connected to the test circuit and the trip mechanism, the test-error mechanism having at least a first position and a second position, the test-error mechanism irreversibly entering the second position when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time,

the test-error mechanism contacting the trip lever when in the second position and the trip lever permanently disabling the trip mechanism when the test-error mechanism is in the second position.

4. The fail-safe electronic circuit breaker of claim 3 wherein test-error mechanism comprises:

a fusible link connected to and retaining a first end and a second end of the test-error mechanism in the first position wherein the fusible link liquefies when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time; and

a bias member positioned between the first end and the second end, the bias member placing the test-error mechanism in the second position when the fusible link is liquefied.

5. The fail-safe electronic circuit breaker of claim 1 wherein the predetermined amount of time is between about thirty milliseconds to amount six hundred milliseconds.

6. The fail-safe electronic circuit breaker of claim 1 wherein the predetermined amount of time is greater than about sixteen milliseconds.

7. The fail-safe electronic circuit breaker of claim 4 wherein the fusible link comprises:

a first conductive member connected to the first end of the test-error mechanism;

a second conductive member connected to the second end of the test-error mechanism;

a connection connecting the first conductive member and the second conductive member and maintaining the test-error mechanism in the first position, the connection being liquefied when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time; and

a spring positioned between the first end and the second end, the spring placing the test-error mechanism in the second position when the connection is liquefied.

8. The fail-safe electronic circuit breaker of claim 4 wherein the fusible link comprises:

a spring connected to a first end of the fusible link;

a plunger connected to the spring;

an electrically resistive member positioned proximate to the plunger for generating heat in the presence of a flowing current; and

a connection connecting the plunger and the electrically resistive member and maintaining the test-error mechanism in a first position, the connection being liquefied when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time, the spring placing the test-error mechanism in the second position when the connection is liquefied.

9. The fail-safe electronic circuit breaker of claim 8 wherein the connection comprises a material having a melting point between about 200°

C. to about 300°

C.

10. The fail-safe electronic circuit breaker of claim 8 wherein the connection comprises solder.

11. The fail-safe electronic circuit breaker of claim 8 further comprising an indicator connected to the plunger indicating when the test-error mechanism is in the second position.

12. The fail-safe electronic circuit breaker of claim 1 wherein the trip mechanism disabler further comprises:

a test-error mechanism connected to the test circuit and the trip mechanism, the test-error mechanism having at least a first position and a second position wherein the test-error mechanism irreversibly enters the second position when the fault detection circuit fails to detect the simulated fault after about a predetermined time;

a heating element connected to a power source and emitting heat when the test-error mechanism is in the second position; and

a bi-metallic strip positioned proximate to the heating element, the bimetallic strip having at least a first state and a second state wherein the bimetallic strip enters the second state after being heated by the heating element and the bi-metallic strip contacting the trip mechanism when in the second state to cause the fail-safe electronic circuit breaker to trip and permanently disable the trip mechanism.

13. The fail-safe electronic circuit breaker of claim 12 wherein test-error mechanism comprises:

a fusible link connected to and retaining a first end and a second end of the test-error mechanism in the first position wherein the fusible link liquefies when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time; and

a bias member positioned between the first end and the second end, the bias member placing the test-error mechanism in the second position when the fusible link is liquefied.

14. The fail-safe electronic circuit breaker of claim 13 wherein the predetermined amount of time is between about thirty milliseconds to amount six hundred milliseconds.

15. The fail-safe electronic circuit breaker of claim 13 wherein the predetermined amount of time is greater than about sixteen milliseconds.

16. The fail-safe electronic circuit breaker of claim 13 wherein the fusible link comprises:

a first conductive member connected to the first end of the test-error mechanism;

a second conductive member connected to the second end of the test-error mechanism;

a connection connecting the first conductive member and the second conductive member and maintaining the test-error mechanism in the first position, the connection being liquefied when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time; and

a spring positioned between the first end and the second end, the spring placing the test-error mechanism in the second position when the connection is liquefied.

17. The fail-safe electronic circuit breaker of claim 13 wherein the fusible link comprises:

a spring connected to a first end of the fusible link;

a plunger connected to the spring;

an electrically resistive member positioned proximate to the plunger for generating heat in the presence of a flowing current; and

a connection connecting the plunger and the electrically resistive member and maintaining the test-error mechanism in a first position, the connection being liquefied when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time, the spring placing the test-error mechanism in the second position when the connection is liquefied.

18. The fail-safe electronic circuit breaker of claim 17 wherein the connection comprises a material having a melting point between about 200°

C. to about 300°

C.

19. The fail-safe electronic circuit breaker of claim 17 wherein the connection comprises solder.

20. The fail-safe electronic circuit breaker of claim 17 further comprising an indicator connected to the plunger indicating when the test-error mechanism is in the second position.

21. The fail-safe electronic circuit breaker of claim 1 wherein the predetermined amount of time is between about thirty milliseconds to amount six hundred milliseconds.

22. The fail-safe electronic circuit breaker of claim 1 wherein the predetermined amount of time is greater than about sixteen milliseconds.

23. A fail-safe electronic circuit breaker comprising:

a fault detection circuit for detecting a circuit fault;

a test circuit connected to the fault detection circuit, the test circuit selectively generating a simulated circuit fault;

a trip mechanism connected to the fault detection circuit and the test circuit, the trip mechanism comprising a trip lever connected to the fault detection circuit for tripping the fail-safe electronic circuit breaker when a circuit fault is detected by the fault detection circuit;

a test-error mechanism connected to the test circuit and the trip mechanism, the test-error mechanism having at least a first position and a second position, the test-error mechanism comprising;

a fusible link connected to the test circuit and the trip mechanism, the fusible link retaining a first end and a second end of the test-error mechanism in the first position wherein the fusible link liquefies when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time; and

a bias member positioned between the first end and the second end, the bias member placing the test-error mechanism in the second position when the fusible link is liquefied, wherein the test-error mechanism contacts the trip lever when in the second position and the trip lever permanently disabling the trip mechanism when the test-error mechanism is in the second position.

24. The fail-safe electronic circuit breaker of claim 23 wherein the predetermined amount of time is between about thirty milliseconds to amount six hundred milliseconds.

25. The fail-safe electronic circuit breaker of claim 23 wherein the predetermined amount of time is greater than about sixteen milliseconds.

26. The fail-safe electronic circuit breaker of claim 23 wherein the fusible link comprises:

a first conductive member connected to the first end of the test-error mechanism;

a second conductive member connected to the second end of the test-error mechanism;

a connection connecting the first conductive member and the second conductive member and maintaining the test-error mechanism in the first position, the connection being liquefied when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time; and

a spring positioned between the first end and the second end, the spring placing the test-error mechanism in the second position when the connection is liquefied.

27. The fail-safe electronic circuit breaker of claim 23 wherein the fusible link comprises:

a spring connected to a first end of the fusible link;

a plunger connected to the spring;

an electrically resistive member positioned proximate to the plunger for generating heat in the presence of a flowing current; and

a connection connecting the plunger and the electrically resistive member and maintaining the test-error mechanism in a first position, the connection being liquefied when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time, the spring placing the test-error mechanism in the second position when the connection is liquefied.

28. The fail-safe electronic circuit breaker of claim 27 wherein the connection comprises a material having a melting point between about 200°

C. to about 300°

C.

29. The fail-safe electronic circuit breaker of claim 27 wherein the connection comprises solder.

30. The fail-safe electronic circuit breaker of claim 27 further comprising an indicator connected to the plunger indicating when the test-error mechanism is in the second position.

31. A fail-safe electronic circuit breaker having a fault detection circuit connected to a test circuit selectively generating a simulated circuit fault, the fail-safe electronic circuit breaker comprising:

a fault detection circuit for detecting a circuit fault;

a test circuit connected to the fault detection circuit, the test circuit selectively generating a simulated circuit fault;

a trip mechanism connected to the fault detection circuit and the test circuit, the trip mechanism tripping the fail-safe electronic circuit breaker when a circuit fault is detected by the fault detection circuit; and

a test-error mechanism connected to the test circuit and the trip mechanism, the test-error mechanism having at least a first position and a second position, the test-error mechanism comprising;

a fusible link connected to the test circuit and retaining a first end and a second end of the test-error mechanism in the first position wherein the fusible link liquefies when the fault detection circuit fails to detect the simulated fault after about the predetermined amount of time;

a bias member positioned between the first end and the second end, the bias member placing the test-error mechanism in the second position when the fusible link is liquefied;

a heating element connected to a power source and emitting heat when the test-error mechanism is in the second position; and

a bimetallic strip positioned proximate to the heating element, the bi-metallic strip having at least a first state and a second state wherein the bimetallic strip enters the second state after being heated by the heating element and the bi-metallic strip causing the trip mechanism to trip the fail-safe electronic circuit breaker when in the second state and permanently disabling the trip mechanism.

32. The fail-safe electronic circuit breaker of claim 31 wherein the predetermined amount of time is between about thirty milliseconds to about six hundred milliseconds.

33. The fail-safe electronic circuit breaker of claim 31 wherein the predetermined amount of time is greater than about sixteen milliseconds.

34. The fail-safe electronic circuit breaker of claim 31 wherein the fusible link comprising:

a first conductive member connected to the first end of the test-error mechanism;

a second conductive member connected to the second end of the test-error mechanism;

a connection connecting the first conductive member and the second conductive member and maintaining the test-error mechanism in the first position, the connection being liquefied when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time; and

a spring positioned between the first end and the second end, the spring placing the test-error mechanism in the second position when the connection is liquefied.

35. The fail-safe electronic circuit breaker of claim 31 wherein the fusible link comprises:

a spring connected to a first end of the fusible link;

a plunger connected to the spring;

an electrically resistive member positioned proximate to the plunger for generating heat in the presence of a flowing current; and

a connection connecting the plunger and the electrically resistive member and maintaining the test-error mechanism in a first position, the connection being liquefied when the fault detection circuit fails to detect the simulated circuit fault after about the predetermined amount of time, the spring placing the test-error mechanism in the second position when the connection is liquefied.

36. The fail-safe electronic circuit breaker of claim 35 wherein the connection comprises a material having a melting point between about 200°

C. to about 300°

C.

37. The fail-safe electronic circuit breaker of claim 35 wherein the connection comprises solder.

38. The fail-safe electronic circuit breaker of claim 35 further comprising an indicator connected to the plunger indicating when the test-error mechanism enters the second position.