Galvanically isolated hybrid contactor
View Patent ↗A hybrid contactor device that provides the ability to use the device with both AC and DC circuits is provided. The hybrid contactor includes a series-parallel arrangement of mechanical contacts with solid state devices, increasing the switching capacity of the mechanical contacts, and maintains galvanic isolation when open. The hybrid contactor includes two mechanical contacts, and is arranged so that one contact closes shortly before the other. The second contact forms a parallel circuit with an electronic switch.
1. A hybrid contactor device, comprising:
a moveable conductive metal bar including a first mechanical contact and a second mechanical contact;
a first terminal configured to electrically engage the first mechanical contact and a second terminal configured to electrically engage the second mechanical contact, the first terminal mechanically offset from the second terminal; and
a solid state MOSFET switch in parallel with the second mechanical contact, the switch configured to control both an AC current carrying breaker and a DC current carrying breaker;
wherein:
when the first mechanical contact is open, galvanic isolation is formed between input and output;
when the first mechanical contact is in a closed position, an electrical and mechanical contact is configured to form with the first terminal relay, the closed position effective to cause power to be applied to the solid state MOSFET switch; and
after a delay caused by the mechanically offset configuration, the second mechanical contact is configured to move to the closed position while the first mechanical contact remains closed, causing a shorting of the solid state MOSFET switch; and
preventing formation of an arc by causing the power to be applied to the solid state MOSFET switch.
2. The contactor device of claim 1 wherein, after the delay, the solid state switch causes current to flow through the contactor device.
3. The contactor device of claim 1 wherein the first mechanical contact and the second mechanical contact are arranged in series.
4. The contactor device of claim 1 wherein the solid state switch is arranged in parallel to the second mechanical contact.
5. The contactor device of claim 1 wherein the first mechanical contact and the second mechanical contact form a double gap contactor with a single activating electromagnetic actuator.
6. The contactor device of claim 1 wherein the solid state switch includes a semiconductor device.
7. The contactor device of claim 6 wherein the semiconductor device is selected from a group consisting of a silicon-controlled rectifier (SCR), field-effect transistor (FET) or other type of transistor.
8. The contactor device of claim 1 wherein the solid state-switch is selected from a group consisting of SCR, three-terminal semiconductor (TRIAC), FET, insulated-gate bipolar transistor (IGBT), or bipolar junction transistor (BJT) switches.
9. A method of operating a hybrid contactor device, comprising the steps of:
providing a first mechanical contact;
providing a second mechanical contact;
providing a bilateral solid state MOSFET switch in communication with the second mechanical contact, the switch configured to control both an AC-type and a DC-type breaker;
providing a first terminal;
receiving, via the first terminal, an electrical engagement from the first mechanical contact;
providing a second terminal; and
receiving, via the second terminal, an electrical engagement from the second mechanical contact;
closing the first mechanical contact, the closing comprising forming mechanical and electrical contact with the first terminal;
causing power to be applied to the solid state MOSFET switch;
conducting, via the solid state MOSFET switch, current in parallel with the second contact;
closing the second mechanical contact while the first mechanical contact remains closed, the closing comprising forming mechanical and electrical contact with the second relay terminal;
causing a shorting of the solid state MOSFET switch, the shorting causing power to be applied to the solid state MOSFET switch and preventing any formation of an arc;
completing the shorting of the solid state switch prior to opening the first contact; and
wherein when the first mechanical contact and second mechanical contact are open, galvanic isolation is formed between input and output.
10. The method of claim 9 wherein, when either of the first mechanical contact or the second mechanical contact are in a closed position, the solid state switch is configured to carry an entire current load.
11. The method of claim 9 wherein, when the first mechanical contact is closed, the solid state switch remains in an open position, and does not flow current through the circuit.
12. The method of claim 9 wherein, upon closure of the second mechanical contact, the solid state switch is shorted, the short effective to cause a substantial portion of the electrical current to change its flow to a low-resistance mechanical path.
13. The method of claim 9 wherein, when the first mechanical contact is in a closed position and the second mechanical contact is still in a switched open position, the method further comprises flowing all current through the first mechanical contact and into the solid state switch.