Electrical switchgear with synchronous control system and actuator

• US 6,538,347 B1
• Filed: 06/30/1999
• Issued: 03/25/2003
• Est. Priority Date: 05/15/1995
• Status: Expired due to Term

• 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
• Primary Examiner(s): FLEMING, FRITZ M
• Application Number:
  US09/343,094
• Time in Patent Office: 1,364 Days
• Field of Search: 307/137, 307/135, 307/136, 361/160, 361/170, 361/152-156
• US Class Current: 307/137
• 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 that senses position information of the at least one contact when the at least one contact is traveling between a fully open position in which electrical current does not flow through the contacts and a closed position in which electrical current flows through the 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;

wherein the position information includes at least one of a position and a velocity of the at least one contact when the at least one contact is traveling between the fully open position and the closed position.

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 at least one contact in one of the fully open position or the closed position.

14. The capacitor switch of claim 1, further comprising a trip mechanism that operates independently of electrical control and that allows an operator of the capacitor switch to manually open switch contacts.

15. The capacitor switch of claim 14, wherein the 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 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 at least one 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 at least one contact away from the other contact.

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

18. The capacitor switch of claim 16, wherein the 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. The closed loop feedback control system of claim 1, wherein the position sensor continuously senses the position information of the at least one contact when the at least one contact is traveling between the fully open position and the closed position.

21. The closed loop feedback control system of claim 1, wherein position information of a contact comprises a postion of the contact.

22. The closed loop feedback control system of claim 1, wherein the processor provides AC waveform synchronized switching by initiating the contacts to close or open when an AC voltage across the contacts is substantially zero.

23. The closed loop feedback control system of claim 1, wherein the processor provides AC waveform synchronized switching by initiating the contacts to close or open when an AC current across the contacts is substantially zero.

24. The closed loop feedback control system of claim 1, wherein the processor provides AC waveform synchronized switching by driving the at least one contact from the fully open position to closed position in accordance with a pre-programmed motion profile.

25. 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 for at least one contact when the at least one contact is traveling between a fully open position in which electrical current does not flow through the contacts and a closed position in which electrical current flows through the contacts; and

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

wherein the contact position information includes at least one of a position and a velocity of the at least one contact when the at least one contact is traveling between the fully open position and the closed position.

26. The method of claim 25, wherein providing AC waveform synchronized switching comprises providing AC waveform synchronized switching on a single AC phase.

27. The method of claim 25, wherein providing AC waveform synchronized switching comprises providing AC waveform synchronized switching on a each phase of a poly-phase AC electrical circuit.

28. The method of claim 25, wherein the AC electrical circuit comprises a power line.

29. The method of claim 25, further comprising comparing the contact position information with a target contact position, and adjusting the contact position based on the comparison.

30. The method of claim 29, wherein the target contact position is based on prior contact position information.

31. The method of claim 25, further comprising determining residual contact life based on the contact position information.

32. The method of claim 25, further comprising determining erosion in electrical switchgear components based on the contact position information.

33. The closed loop feedback control method of claim 25, wherein generating contact position information for the at least one contact comprises continuously sampling a position of the at least one contact.

34. The closed loop feedback control method of claim 25, wherein analyzing the contact position information to provide AC waveform synchronized switching comprises initiating the contacts to close or open when an AC voltage across the contacts is substantially zero.

35. The closed loop feedback control method of claim 25, wherein analyzing the contact position information to provide AC waveform synchronized switching comprises initiating the contacts to close or open when an AC current across the contacts is substantially zero.

36. The closed loop feedback control method of claim 25, wherein the analyzing the contact position information to provide AC waveform synchronized switching comprises driving the at least one contact from the fully open position to the fully closed position in accordance with a pre-programmed motion profile.