SHAPE MEMORY ALLOY ACTUATED CIRCUIT BREAKER

• US 20120169451A1
• Filed: 12/30/2010
• Published: 07/05/2012
• Est. Priority Date: 12/30/2010
• Status: Active Grant

• Current Assignee: ABB SPA (ABB Limited)
• Original Assignee: General Electric Company
• Inventors: Kumfer, Brent Charles, Mooney, Brian Frederick, Papallo, Thomas Frederick
• Granted Patent: US 8,830,026 B2
• Time in Patent Office: Days
• US Class Current: 337/382
• CPC Class Codes: H01H 71/145 using shape memory materials H01H71/16 takes precedence

Abstract

A thermal trip unit for a circuit breaker having a primary conductive path for conducting a load current is provided. The thermal trip unit comprises a shape memory alloy (SMA) member adapted to change from a first shape to a second shape at a predetermined thermal condition, a holding member coupled electrically in series with the circuit breaker primary conductive path, said holding member arranged to operatively support said SMA member, wherein said SMA member is configured and disposed within the circuit breaker to trigger a trip response of the circuit breaker at said predetermined thermal condition.

Claims

1. A thermal trip unit for a circuit breaker, the circuit breaker including a primary conductive path for conducting a load current, the thermal trip unit comprising:

a shape memory alloy (SMA) member adapted to change from a first shape to a second shape at a predetermined thermal condition;

a holding member coupled electrically in series with the circuit breaker primary conductive path, said holding member arranged to operatively support said SMA member;

wherein said SMA member is configured and disposed within the circuit breaker to trigger a trip response of the circuit breaker at said predetermined thermal condition.

2. The thermal trip unit of claim 1 wherein said primary conductive path is operatively arranged and disposed to substantially limit a current flow through the SMA member.

3. The thermal trip unit of claim 1 wherein said holding member is further configured and disposed to operatively heat said SMA member.

4. The thermal trip unit of claim 2 wherein said SMA member is adapted to elongate at said predetermined thermal condition.

5. The thermal trip unit of claim 2 wherein said SMA member has a coil shape.

6. The thermal trip unit of claim 3 wherein said holding member has a hollow cylindrical shape.

7. The thermal trip unit of claim 5, further comprising:

a conductive tube, said tube being connected to said holding member and disposed within said holding member diameter and further disposed at least partially within the inside diameter of said SMA member.

8. A circuit breaker pole, comprising:

a primary conductive path for conducting a load current

a thermal trip unit, coupled to said primary conductive path, said trip unit comprising;

a shape memory alloy (SMA) member adapted to change from a first shape to a second shape at a predetermined thermal condition;

a holding member coupled electrically in series with the circuit breaker primary conductive path, said holding member arranged to operatively support said SMA member;

wherein said SMA member is configured and disposed within the circuit breaker to trigger a trip response of the circuit breaker at said predetermined thermal condition.

9. The circuit breaker pole of claim 8 wherein said primary conductive path is operatively arranged and disposed to substantially limit a current flow through the SMA member.

10. The circuit breaker pole of claim 8 wherein said holding member is further configured and disposed to operatively heat said SMA member.

11. The circuit breaker pole of claim 9 wherein said SMA member is adapted to elongate at said predetermined thermal condition.

12. The circuit breaker pole of claim 8 wherein said SMA member has a coil shape.

13. The circuit breaker pole of claim 9 wherein said holding member is of a hollow cylindrical shape.

14. The circuit breaker pole of claim 12 further comprising a conductive tube, said tube being disposed in connected to said holding member and located within said holding member diameter and at least partially within the inside diameter of said SMA member.

15. A circuit breaker, comprising:

a pole comprising a primary conductive path for conducting a load current

a thermal trip unit, coupled to said primary conductive path, said trip unit comprising;

a shape memory alloy (SMA) member adapted to change from a first shape to a second shape at a predetermined thermal condition;

a holding member coupled electrically in series with the circuit breaker primary conductive path, said holding member arranged to operatively support said SMA member;

wherein said SMA member is configured and disposed within the circuit breaker to trigger a trip response of the circuit breaker at said predetermined thermal condition.

16. The circuit breaker of claim 15 wherein said primary conductive path is operatively arranged and disposed to substantially limit a current flow through the SMA member.

17. The circuit breaker of claim 15 wherein said holding member is further configured and disposed to operatively heat said SMA member.

18. The circuit breaker of claim 15 wherein said SMA member is adapted to elongate at said predetermined thermal condition.

19. The circuit breaker of claim 16 wherein said SMA member is of a coil shape.

20. The circuit breaker of claim 17 wherein said holding member is of a hollow cylindrical shape.

21. The circuit breaker of claim 19 further comprising a conductive tube, said tube being disposed in connected to said holding member and located within said holding member diameter and at least partially within the inside diameter of said SMA member.