Hybrid high voltage DC contactor with arc energy diversion
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.
1. 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:
produce multiple activations of the shunt during movement of the contacts away from each other; and
produce multiple deactivations of the shunt during said movement of the contacts.
2. The contactor of claim 1 wherein the contactor is rated to interrupt current in the circuit when the circuit is supplying power to a load.
3. The contactor of claim 1 wherein the contactor is rated to interrupt short-circuit current in the circuit.
4. The contactor of claim 3 wherein the contactor is rated to interrupt direct current.
5. The contactor of claim 1 wherein the electrical shunt comprises a solid-state switch.
6. The contactor of claim 1 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.
7. The contactor of claim 6 wherein a cumulative elapsed time for all of the pulsed operation does not exceed 50% of the first time period.
8. The contactor of claim 6 wherein none of the pulsed operations is performed for more than 20 microseconds (μsec) or less than 1 μsec.
9. 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;
performing multiple operations of an electrical shunt around the contacts during the predetermined time period;
disabling the electrical shunt multiple times during the time period: and
passing power between the contacts during said moving whenever the electrical shunt is disabled.
10. The method of claim 9 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.
11. The method of claim 9 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.
12. The method of claim 11 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.
13. The method of claim 9 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.