Automatic transfer switch

Patent metadata

Field	Value
Publication number	US-9935495-B2
Application number	US-201615191847-A
Country	US
Kind code	B2
Filing date	Jun 24, 2016
Priority date	Jun 24, 2016
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

Automatic transfer switch for switching an electrical load between two power sources. In one example, the automatic transfer switch includes four latching relays and an electronic controller. A first power source line connection is connected to an electrical load line connection via a first latching relay. A first power source neutral connection is connected to an electrical load neutral connection via a second latching relay. A second power source line connection is connected to the electrical load line connection via a third latching relay. A second power source neutral connection is connected to the electrical load neutral connection via a fourth latching relay. The electronic controller connects the second power source to the electrical load when a voltage of the first power source is less than a first threshold, and connects the first power source to the electrical load when the voltage is greater than a second threshold.

First claim

What is claimed is:

1. An automatic transfer switch comprising:
a first latching relay having an opened state and a closed state, wherein a line connection of a first power source is connected to a line connection of an electrical load via the first latching relay when the first latching relay is in its closed state;
a second latching relay having an opened state and a closed state, wherein a neutral connection of the first power source is connected to a neutral connection of the electrical load via the second latching relay when the second latching relay is in its closed state;
a third latching relay having an opened state and a closed state, wherein a line connection of a second power source is connected to the line connection of the electrical load via the third latching relay when the third latching relay is in its closed state;
a fourth latching relay having an opened state and a closed state, wherein a neutral connection of the second power source is connected to the neutral connection of the electrical load via the fourth latching relay when the fourth latching relay is in its closed state; and
an electronic controller electrically coupled to the first latching relay, the second latching relay, the third latching relay, and the fourth latching relay, the electronic controller configured to
determine a voltage of the first power source,
connect the second power source to the electrical load when the voltage of the first power source is less than a first threshold, and
connect the first power source to the electrical load when the voltage of the first power source is greater than a second threshold.

2. The automatic transfer switch of claim 1 , wherein the first latching relay is latched in either the opened state or the closed state without a holding current supplied to the first latching relay.

3. The automatic transfer switch of claim 1 , wherein the second threshold is greater than the first threshold.

4. The automatic transfer switch of claim 1 , wherein the first latching relay and the second latching relay are in their closed state when the first power source is electrically coupled to the electrical load, and wherein the third latching relay and the fourth latching relay are in their closed state when the second power source is electrically coupled to the electrical load.

5. The automatic transfer switch of claim 4 , wherein the electronic controller is further configured to
disconnect the second power source from the electrical load when the voltage of the first power source is greater than the second threshold, and
disconnect the first power source from the electrical load when the voltage of the first power source is less than the first threshold.

6. The automatic transfer switch of claim 5 , wherein the first latching relay and the second latching relay are in their opened state when the first power source is disconnected from the electrical load, wherein the third latching relay and the fourth latching relay are in their opened state when the second power source is disconnected from the electrical load.

7. The automatic transfer switch of claim 1 , further comprising an optical sensor electrically coupled to the electronic controller, wherein the electronic controller is further configured to
receive a signal from the optical sensor, and
responsive to receiving the signal:
disconnect the first power source from the electrical load, and
connect the second power source to the electrical load.

8. The automatic transfer switch of claim 1 , further comprising an interlocking circuit including:
a plurality of position sensors configured to detect positions of the first latching relay, the second latching relay, the third latching relay, and the fourth latching relay,
a plurality of electrical switches positioned between the electronic controller, the first latching relay, the second latching relay, the third latching relay, and the fourth latching relay, and
an interlocking controller electrically coupled to the plurality of position sensors and the plurality of electrical switches, the interlocking controller configured to selectively open and close the plurality of electrical switches based on the positions detected by the plurality of position sensors.

9. The automatic transfer switch of claim 8 , wherein the plurality of position sensors includes at least one type of sensor selected from a group consisting of an optical sensor, a hall effect sensor, a micro switch sensor, and an electrical feedback sensor.

10. The automatic transfer switch of claim 9 , wherein the third latching relay and the fourth latching relay are their opened state when at least one of the first latching relay and the second latching relay is in the closed state, wherein the first latching relay and the second latching relay are their opened state when at least one of the third latching relay and the fourth latching relay is in the closed state.

11. The automatic transfer switch of claim 1 , wherein the voltage of the first power source includes a voltage difference between the line connection of the first power source and the neutral connection of the first power source.

12. A method of switching an electrical load between a first power source and a second power source, the method comprising:
determining, with an electronic controller, a voltage of the first power source;
opening a first latching relay when the voltage of the first power source is less than a threshold, the first latching relay connected between a line connection of the first power source and a line connection of the electrical load;
opening a second latching relay after opening the first latching relay, the second latching relay connected between a neutral connection of the first power source and a neutral connection of the electrical load;
closing a fourth latching relay after opening the second latching relay, the fourth latching relay connected between a neutral connection of the second power source and the neutral connection of the electrical load; and
closing a third latching relay after closing the fourth latching relay, the third latching relay connected between a line connection of the second power source and the line connection of the electrical load.

13. The method of claim 12 , wherein the threshold is a first threshold, wherein the method further comprising:
opening the third latching relay when the voltage of the first power source is greater than a second threshold;
opening the fourth latching relay after opening the third latching relay;
closing the second latching relay after opening the fourth latching relay; and
closing the first latching relay after closing the second latching relay.

14. The method of claim 13 , wherein the second threshold is greater than the first threshold.

15. The method of claim 12 , further comprising:
detecting, via an optical sensor, an optical signal;
disconnecting, via the first latching relay and the second latching relay, the first power source from the electrical load in response to detecting the optical signal; and
connecting, via the third latching relay and the fourth latching relay, the second power source to the electrical load.

16. The method of claim 12 , further comprising:
receiving, via an communication module, a signal; and
disconnecting, via the first latching relay and the second latching relay, the first power source from the electrical load in response to receiving the signal; and
connecting, via the third latching relay and the fourth latching relay, the second power source to the electrical load.

17. The method of

Assignees

• Electronic Theatre Controls Inc

Inventors

• Thurk John
• Burke Kevin

Classifications

• H02J9/06 Primary

  with automatic change-over {, e.g. UPS systems} · CPC title