Micro-electromechanical system based selectively coordinated protection systems and methods for electrical distribution

• US 7,944,660 B2
• Filed: 06/15/2007
• Issued: 05/17/2011
• Est. Priority Date: 06/15/2007
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: General Electric Company
• Inventors: Premerlani, William James, Subramanian, Kanakasabapathi, Pitzen, Charles Stephan, Caggiano, Robert Joseph, Kumfer, Brent Charles
• Primary Examiner(s): PATEL, DHARTI HARIDAS
• Application Number:
  US11/763,672
• Publication Number:
  US 20080310062A1
• Time in Patent Office: 1,432 Days
• Field of Search: 361/62, 361/71, 361 74- 75, 361/93.1, 361/93.4
• US Class Current: 361/71
• CPC Class Codes: H01H 2071/008 Protective switches or relays using micromechanics
• CPC Class Codes: H01H 47/002 Monitoring or fail-safe circuits
• CPC Class Codes: H01H 59/0009 making use of micromechanics
• CPC Class Codes: H01H 71/1081 Modifications for selective or back-up protection; Correlation between feeder and branch circuit breaker circuits H02H3/06, H02H7/26
• CPC Class Codes: H01H 9/541 Contacts shunted by semiconductor devices

Abstract

Electrical distribution systems implementing micro-electromechanical system based switching devices. Exemplary embodiments include a method in an electrical distribution system, the method including determining if there is a fault condition in a branch of the electrical distribution system, the branch having a plurality of micro electromechanical system (MEMS) switches, re-closing a MEMS switch of the plurality of MEMS switches, which is furthest upstream in the branch and determining if the fault condition is still present. Exemplary embodiments include an electrical distribution system, including an input port for receiving a source of power, a main distribution bus electrically coupled to the input port, a service disconnect MEMS switch disposed between and coupled to the input port and the main distribution bus and a plurality of electrical distribution branches electrically coupled to the main distribution bus.

Claims

1. In an electrical distribution, a method, comprising

determining if there is a fault condition downstream in a branch of the electrical distribution system, the branch having a plurality of micro electromechanical system (MEMS) switches, wherein a trip threshold for successive upstream ones of each of the plurality of MEMS switches is set higher than a successive downstream one of the plurality of MEMS switches, and a trip time for the successive upstream ones of each of the plurality of MEMS switches is set lower than a successive downstream one of the plurality of MEMS switches, and wherein a MEMS switch that is closest to the fault condition downstream trips before any other of the plurality of MEMS switches;

re-closing a MEMS switch of the plurality of MEMS switches, which is furthest upstream in the branch; and

determining if the fault condition is still present.

2. The method as claimed in claim 1 further comprising determining whether there are still any MEMS switches of the plurality of MEMS switches that are open in the branch if it is determined that the fault condition is no longer present.

3. The method as claimed in claim 2 further comprising re-closing the next furthest MEMS switch of the plurality of MEMS switches if it is determined that there are still MEMS switches open in the branch.

4. The method as claimed in claim 2 further comprising resuming electrical distribution system operation if it is determined that there are no MEMS switches of the plurality of MEMS switches open in the branch.

5. The method as claimed in claim 1 further comprising re-opening the MEMS switch that is furthest upstream in the branch if it is determined that the fault condition is still present.

7. The method as claimed in claim 1 further comprising:

monitoring a load current value of a load current passing through the plurality of MEMS switches; and

determining if the monitored load current value varies from a predetermined load value.

8. The method as claimed in claim 7 further comprising generating a fault signal in response to the monitored load current value varying from the predetermined load current value.

9. The method as claimed in claim 8 further comprising determining if the varying in the load current value was at least one of a nuisance trip and a non-nuisance trip.

6. The method as claimed in claimed 5 further comprising clearing the fault from the branch the electrical distribution system.

10. An electrical distribution system, comprising:

an input port for receiving a source of power;

a main distribution bus electrically coupled to the input port;

a service disconnect micro electromechanical system (MEMS) switch disposed between and coupled to the input port and the main distribution bus;

a plurality of electrical distribution branches electrically coupled to the main distribution bus;

a plurality of MEMS switches distributed along each of the plurality of electrical distribution branches, wherein a trip threshold for successive upstream ones of each of the plurality of MEMS switches is set higher than a successive downstream one of the plurality of MEMS switches, and a trip time for the successive upstream ones of each of the plurality of MEMS switches is set lower than a successive downstream one of the plurality of MEMS switches, and wherein a MEMS switch that is closest to a fault condition downstream trips before any other of the plurality of MEMS switches;

wherein the system determines whether there is a fault condition in one of the plurality of electrical distribution branches, re-closes a MEMS switch of the plurality of MEMS switches, which is furthest upstream in the branch and determines if the fault condition is still present.

11. The system as claimed in claim 10 wherein each of the plurality of electrical distribution branches further comprise a plurality of load circuits electrically coupled to a respective electrical distribution branch.

12. The system as claimed in claim 11 further comprising a distribution branch MEMS switch disposed between and electrically coupled to the main distribution bus and the plurality of load circuits.

13. The system as claimed in claim 12 further comprising a step-down transformer disposed between and coupled to the distribution branch MEMS switch and the plurality of load circuits.

14. The system as claimed in claim 11 further comprising a plurality of load circuit MEMS switches distributed on each of the plurality of load circuits.

15. The system as claimed in claim 10 further comprising:

a logic circuit in electrical communication with the plurality of electrical distribution branches; and

a power stage circuit in electrical communication with the logic circuit.

16. The system as claimed in claim 15 further comprising an over-current protection circuit in electrical communication with the logic circuit and the power stage circuit.

17. The system as claimed in claim 16 wherein the plurality of MEMS switches is in electrical communication with the over-protection circuit.

18. The system as claimed in claim 16 wherein the logic circuit is configured to monitor a load current and a load voltage.

19. The system as claimed in claim 18 wherein in response to at least one of a load current and a load voltage varying from a predetermined value, a fault signal is generated and transmitted to the over-current protection circuit.