HYBRID HIGH VOLTAGE DC CONTACTOR WITH ARC ENERGY DIVERSION

• US 20090168273A1
• Filed: 01/02/2008
• Published: 07/02/2009
• Est. Priority Date: 01/02/2008
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Yu, Wenjiang, Liu, Zhenning, Cheng, Shaobin
• Granted Patent: US 7,817,382 B2
• Time in Patent Office: Days
• US Class Current: 361/13
• CPC Class Codes: H01H 9/542 Contacts shunted by static switch means

Abstract

A contactor may operate to interrupt current in a circuit while the circuit is operating under load. A shunt is provided to by-pass surge power current around contacts to reduce arcing. The shunt includes a solid-state switch that may be operated in a series of pulses during movement of the contacts. The pulse control unit may detect a potential for arcing and then provide for periodic pulsing operation of the shunt. Because the solid-state switch may operate discontinuously, the contactor may be constructed with a switch that is selected on a basis of its pulse rating.

Claims

1. An apparatus for interrupting current in a circuit comprising:

contacts through which the current passes;

the contacts moving away from one another during current interruption;

a shunt to by-pass surge power around the contacts when current is interrupted;

the shunt being operative during a portion of a time period that the contacts move; and

the shunt being inoperative during a portion of the time period.

2. The apparatus of claim 1 wherein the shunt is periodically operative during said time period.

3. The apparatus of claim 1 wherein the shunt comprises a solid state switch.

4. The apparatus of claim 3 wherein:

the circuit has a short-circuit rating of a predetermined value;

the switch is pulse-rated at the predetermined value

5. The apparatus of claim 4 wherein a nominal rating of the switch is less than 50% of the short-circuit rating.

6. The apparatus of claim 1 further comprising:

a contactor; and

a pulsing control unit that acts responsively to surge power levels in the contactor to produce switching signals that drive the shunt in a pulsed mode.

7. The apparatus of claim 6 wherein the switching signals are produced to operate the shunt for predetermined pulse periods.

8. An electrical power circuit comprising:

a contactor with movable contacts;

an electrical shunt to by-pass current around the contacts; and

a pulse control to periodically operate the shunt during movement of the contacts.

9. The contactor of claim 8 wherein the contactor is rated to interrupt current in the circuit when the circuit is supplying power to a load.

10. The contactor of claim 8 wherein the contactor is rated to interrupt short-circuit current in the circuit.

11. The contactor of claim 10 wherein the contactor is rated to interrupt direct current.

12. The contactor of claim 8 wherein the electrical shunt comprises a solid-state switch.

13. The contactor of claim 8 wherein:

the contacts move apart from one another during a first time period;

the shunt is operated in a series of pulsed operations during the first time period; and

none of the pulsed operations extends individually for more than 20% of the first time period.

14. The contactor of claim 13 wherein a cumulative elapsed time for all of the pulsed operation does not exceed 50% of the first time period.

15. The contactor of claim 13 wherein none of the pulsed operations is performed for more than 20 microseconds (μ

sec) or less than 1 μ

sec.

16. A method for interrupting current in a circuit under load conditions comprising the steps of:

moving conducting contacts away from one another for a predetermined time period;

detecting electrical power at the contacts during the step of moving the contacts;

determining if the detected power is sufficient to initiate arcing at the contacts;

operating an electrical shunt around the contacts for a portion of the predetermined time period if the detected power is sufficient for arcing initiation; and

disabling the electrical shunt for a portion of the time period.

17. The method of claim 16 wherein:

the step of moving the contacts is performed for a first period of time; and

the step of operating the electrical shunt is performed in at least one pulse having a pulse time period no greater than 20% of the first period of time.

18. The method of claim 16 wherein:

operating the electrical shunt is performed in a series of pulsed operation steps; and

disabling the electrical shunt is performed in a series of pulsed operations intervening the steps of operating the shunt.

19. The method of claim 18 wherein:

the step of moving the contacts is performed for a surge period of time; and

pulsed operations of the shunt are performed in pulses of no more than 20% of the surge period.

20. The method of claim 16 wherein:

the step of operating the shunt comprises closing a solid-state switch; and

the step of operating the shunt is completed within a time that does not exceed a time period on which a pulse-rating of the switch is based.