Electrical switchgear with synchronous control system and actuator

• US 20030071522A1
• Filed: 11/22/2002
• Published: 04/17/2003
• Est. Priority Date: 05/15/1995
• Status: Active Grant

• Current Assignee: Mcgraw-Edison Company (Eaton Corporation PLC.)
• Original Assignee: Mcgraw-Edison Company (Eaton Corporation PLC.)
• Inventors: Dunk, Michael Peter, Mankowski, Aleksander, Jochum, Debra Jennifer, Knotek, Charles John, Baranowski, John Francis
• Granted Patent: US 6,921,989 B2
• Time in Patent Office: Days
• US Class Current: 307/116
• CPC Class Codes: H01H 11/0062 Testing or measuring non-electrical properties of switches, e.g. contact velocity monitoring contacts H01H1/0015; monitoring gas density H01H33/563; monitoring vacuum H01H33/668; calibrating H01H69/01; adjusting H01H71/74; testing of electrical properties G01R31/333
• CPC Class Codes: H01H 2009/566 with self learning, e.g. measured delay is used in later actuations
• CPC Class Codes: H01H 3/227 Interlocked hand- and power-operating mechanisms
• CPC Class Codes: H01H 33/593 for ensuring operation of the switch at a predetermined point of the ac cycle for multipolar switches H01H9/563
• CPC Class Codes: H01H 5/045 making use of cooperating spring loaded wedging or camming parts between operating member and contact structure
• CPC Class Codes: H01H 9/563 for multipolar switches, e.g. different timing for different phases, selecting phase with first zero-crossing

Abstract

A closed loop feedback system controls electrical switchgear that moves at least one contact relative to another contact to switch power on and off in an AC electrical circuit. The control system includes a position feedback device that is operatively coupled to at least one of the two contacts to produce contact position information. A processor receives and analyzes the contact position information to control contact motion to provide AC waveform synchronized switching. The electrical switchgear may be a capacitor switch that includes a bi-stable over-toggle latching device. The latching device maintains the contacts in one of an open stable position in which electrical current does not flow through the contacts or a closed stable position in which electrical current flows through the contacts.

Claims

1. A closed loop feedback control system for electrical switchgear that moves at least one contact relative to another contact to switch power on and off in an AC electrical circuit, the control system comprising:

a position sensor, operatively coupled to at least one of the two contacts to produce contact position information; and

a processor configured to receive and analyze the contact position information to control contact motion to provide AC waveform synchronized switching.

2. The closed loop feedback control system of claim 1, wherein the processor controls a single AC phase of the AC electrical circuit.

3. The closed loop feedback control system of claim 1, wherein the AC electrical circuit comprises a poly-phase circuit and the processor controls each phase of the AC electrical circuit.

4. The closed loop feedback control system of claim 1, wherein the AC electrical circuit comprises a power line.

5. The closed loop feedback control system of claim 1, wherein the processor controls contact motion based on a comparison between the contact position information and a target contact position.

6. The closed loop feedback control system of claim 5, wherein the target contact position is based on prior contact position information.

7. The closed loop feedback control system of claim 1, wherein the processor uses the contact position information to determine residual contact life.

8. The closed loop feedback control system of claim 1, wherein the processor uses the contact position information to determine erosion in electrical switchgear components.

9. The closed loop feedback control system of claim 1, further comprising a hermetically-sealed bottle that houses the switchgear contacts.

10. The closed loop feedback control system of claim 9, wherein the processor uses the contact position information to detect fractures or leaks in the bottle.

11. A capacitor switch including the feedback system of claim 1.

12. The capacitor switch of claim 11, wherein the processor uses the contact position information to determine erosion and wear in the capacitor switch.

13. The capacitor switch of claim 11, further comprising a latching device that maintains the contacts in one of an open stable position in which electrical current does not flow through the contacts or a closed stable position in which electrical current flows through the contacts.

14. The capacitor switch of claim 11, further comprising a mechanical trip mechanism that allows an operator of the capacitor switch to manually open switch contacts.

15. The capacitor switch of claim 14, wherein the mechanical trip mechanism, when activated by the operator, opens switch contacts at least as fast as the closed loop feedback control system.

16. The capacitor switch of claim 14, wherein the mechanical trip mechanism comprises:

a trip lever;

a handle that, when pulled by the operator, rotates the trip lever;

a compression spring;

a trip plunger that couples the trip lever to the compression spring such that rotation of the trip lever pushes the trip plunger in a direction that compresses the compression spring;

a spring plate coupling the compression spring to the movable contact;

a trip finger that rotates away from the compression spring when contacted by the trip plunger to release the spring plate and move the movable contact away from the other contact.

17. The capacitor switch of claim 16, wherein the mechanical trip mechanism further comprises a return spring that, after operator activation, automatically resets the mechanical trip mechanism independently from closed loop feedback control system operations.

18. The capacitor switch of claim 16, wherein the mechanical trip mechanism may be reset by the operator after operator-activation.

19. The capacitor switch of claim 16, wherein contacts remain open until the closed loop feedback control system moves the contacts closed.

20. A closed loop feedback control method for controlling electrical switchgear that moves at least one contact relative to another contact to switch power on and off in an AC electrical circuit, the method comprising:

generating contact position information; and

analyzing the contact position information to control contact motion to provide AC waveform synchronized switching.

21. The method of claim 20, wherein providing AC waveform synchronized switching comprises providing AC waveform synchronized switching on a single AC phase.

22. The method of claim 20, wherein providing AC waveform synchronized switching comprises providing AC waveform synchronized switching on a each phase of a poly-phase AC electrical circuit.

23. The method of claim 20, wherein the AC electrical circuit comprises a power line.

24. The method of claim 20, further comprising comparing the contact position information with a target contact position, and adjusting the contact position based on the comparison.

25. The method of claim 24, wherein the target contact position is based on prior contact position information.

26. The method of claim 20, further comprising determining residual contact life based on the contact position information.

27. The method of claim 20, further comprising determining erosion in electrical switchgear components based on the contact position information.

28. A latching device used in an electrical switchgear, the latching device comprising:

a shaft coupled to a contact of the switchgear and operable to move along a shaft axis between a first stable position in which an electrical path including the contact is closed and a second stable position in which an electrical path including the contact is open;

a piston operable to move along a piston axis;

a biasing device coupled to the piston to exert a biasing force on the piston along the piston axis; and

a linkage coupling the piston to the shaft;

wherein the linkage is configured such that the biasing force on the piston is transferred to the shaft to bias the shaft to one of the stable positions.

29. The latching device of claim 28, wherein the shaft is operable to move along the shaft axis between the first stable position, the second stable position, and a third stable position in which an electrical path including the contact is open.

30. The latching device of claim 28, wherein the piston axis is perpendicular to the shaft axis.

31. The latching device of claim 28, further comprising a biasing adjustment that adjusts the biasing force of the biasing device.

32. The latching device of claim 28, further comprising a biasing retainer that fixes the biasing force of the biasing device.

33. The latching device of claim 28, further comprising:

a second piston operable to move along a second piston axis;

a second biasing device coupled to the second piston to exert a second biasing force on the second piston along the second piston axis; and

a second linkage coupling the second piston to the shaft;

wherein the second linkage is configured such that the second biasing force is transferred to the shaft to bias the shaft to one of the stable positions.

34. The latching device of claim 33, wherein the shaft is operable to move along the shaft axis between the first stable position, the second stable position, and a third stable position in which an electrical path including the contact is open.

35. The latching device of claim 28, wherein the biasing device comprises a spring.

36. The latching device of claim 28, wherein the shaft is insulated from the contact.

37. The latching device of claim 28, wherein the first stable position is constrained such that the biasing force is maximally coupled to the contact through the shaft.

38. The latching device of claim 37, wherein the constraint ensures that the electrical path is closed in the first stable position.

39. The latching device of claim 37, wherein the constraint accounts for contact erosion.

40. The latching device of claim 28, wherein the second stable position is constrained such that the biasing force is maximally coupled to the shaft along the shaft axis.

41. The latching device of claim 28, wherein the piston is operable to move a distance that ensures that the electrical path is closed in the first stable position and that the electrical path is open in the second stable position.

42. The latching device of claim 28, further comprising a shock. absorbing system that comprises:

at least one shock absorbing piston operable to move along a shock absorbing axis and coupled to the shaft; and

at least one shock absorbing biasing device coupled to a shock absorbing piston to exert a shock absorbing biasing force on the shock absorbing piston along the shock absorbing axis;

wherein the shock absorbing piston is configured such that the shock absorbing biasing force dampens contact bounce at at least one stable position.

43. The latching device of claim 42, wherein the shock absorbing axis is parallel to the shaft axis.

44. The latching device of claim 42, wherein the shock absorbing biasing force prevents contact bounce at at least one stable position.

45. The latching device of claim 28, wherein the shaft is coupled to multiple contacts of the switchgear.

46. The latching device of claim 45, wherein each contact corresponds to a phase of polyphase AC power.