Automatic transfer switch

• US 9,595,846 B2
• Filed: 01/16/2014
• Issued: 03/14/2017
• Est. Priority Date: 01/18/2013
• Status: Active Grant

• Current Assignee: Milbank Manufacturing Company
• Original Assignee: Milbank Manufacturing Company
• Inventors: Siglock, John V., Glasgow, Shawn J., Nowell, Andrew John
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Dominique, Emmanuel R
• Application Number:
  US14/157,177
• Publication Number:
  US 20140203648A1
• Time in Patent Office: 1,153 Days
• Field of Search: 307/64
• US Class Current: 1/1
• CPC Class Codes: H01H 2300/018 Application transfer; between utility and emergency power supply
• CPC Class Codes: H01H 47/004 using plural redundant serial connected relay operated contacts in controlled circuit
• CPC Class Codes: H02J 9/061 for DC powered loads

Abstract

Aspects of the present disclosure involve systems, methods, and the like, for an automatic transfer switch (ATS) of a power system. The ATS allows for switching between two or more power systems while preventing back-feeding of the power systems. To provide the safety features of the ATS, a safety circuit and control board may be implemented with the magnetic latching relays to control the actions of the latching relays and provide the switching function of the ATS. In one particular embodiment, the safety board comprises one or more electromechanical relays positioned between the controlling electronics of the control board and the magnetic latching relays. The safety board design contains measures to ensure it still functions if one of the disconnect switches is not connected, if one of the connections to a first load phase, a second load phase or neutral is lost and if the main control board is not connected.

Claims

1. A system for an automatic transfer switch, the system comprising:

a first power source connection electrically connected to a first power source;

a second power source connection electrically connected to a second power source;

a first electromagnetic latch connected between the first power source and a load;

a second electromagnetic latch connected between the second power source and a load;

a safety circuit in electrical communication with the first electromagnetic latch and the second electromagnetic latch, the safety circuit comprising a plurality of loop connections and a plurality of serially connected safety stage circuits each comprising at least one electromechanical relay in electrical communication with the first electromagnetic latch or the second electromagnetic latch; and

a control circuit in electrical communication with the safety circuit, the control circuit configured to provide one or more control signals comprising an OPEN signal to the first electromagnetic latch, an OPEN signal to the second electromagnetic latch and a CLOSED signal to control the operation of the first electromagnetic latch and the second electromagnetic latch;

wherein the safety circuit further comprises a first stage comprising a first loop connection in electrical communication between the CLOSED signal from the control circuit and the first electromagnetic latch and a second loop connection in electrical communication between the CLOSED signal from the control circuit and the second electromagnetic latch.

2. The system of claim 1 wherein the safety circuit further comprises a second stage, wherein the second stage comprises:

a first status switch relay in electrical communication with the first electromagnetic latch and connected in series between the CLOSED signal from the control circuit and the second electromagnetic latch such that when the first electromagnetic latch is closed, the first status switch relay is open to prevent the CLOSED signal from being received at the second electromagnetic latch.

3. The system of claim 2 wherein the second stage further comprises:

a second status switch relay in electrical communication with the second electromagnetic latch and connected in series between the CLOSED signal from the control circuit and the first electromagnetic latch such that when the second electromagnetic latch is closed, the second status switch relay is open to prevent the CLOSED signal from being received at the first electromagnetic latch.

4. The system of claim 1 wherein the control signal of the control circuit further comprises an electromagnetic latch select signal and the safety circuit further comprises a third stage, wherein the third stage comprises:

a first select switch relay in electrical communication between the OPEN signal to the first electromagnetic latch and the first electromagnetic latch and a second select switch relay in electrical communication between the CLOSE signal and the first electromagnetic latch, wherein an asserted electromagnetic latch select signal from the control circuit operates to allow the first electromagnetic latch to receive the OPEN signal to the first electromagnetic latch and the CLOSE signal.

5. The system of claim 4 wherein the third stage further comprises:

a third select switch relay in electrical communication between the OPEN signal to the second electromagnetic latch and the second electromagnetic latch and a fourth select switch relay in electrical communication between the CLOSE signal and the second electromagnetic latch, wherein a de-asserted electromagnetic latch select signal from the control circuit operates to allow the second electromagnetic latch to receive the OPEN signal to the second electromagnetic latch and the CLOSE signal.

6. The system of claim 1 wherein the safety circuit further comprises a fourth stage, wherein the fourth stage comprises:

a load first phase relay electrically connected to a first load phase busbar and connected in series between the CLOSED signal from the control circuit and the first electromagnetic latch and the second electromagnetic latch such that when the load first phase relay is energized by the first load phase busbar, the load first phase relay is open to prevent the CLOSED signal from being received at the first electromagnetic latch and the second electromagnetic latch; and

a load second phase relay electrically connected to a second load phase busbar and connected in series between the CLOSED signal from the control circuit and the first electromagnetic latch and the second electromagnetic latch such that when the load second phase relay is energized by the second load phase busbar, the second first phase relay is open to prevent the CLOSED signal from being received at the first electromagnetic latch and the second electromagnetic latch.

7. The system of claim 1 wherein the safety circuit further comprises a fifth stage, wherein the fifth stage comprises:

a power status switch relay electrically connected to a power signal from the control board and connected in series between the CLOSED signal from the control circuit and the first electromagnetic latch and the second electromagnetic latch such that when the power status switch relay is energized by the power signal, the power status switch relay is closed to allow the CLOSED signal to be received at the first electromagnetic latch and the second electromagnetic latch.

8. An automatic power transfer switch comprising:

a first power source connection electrically connected to a first power source;

a second power source connection electrically connected to a second power source;

a first electromagnetic latch connected between the first power source and a load;

a second electromagnetic latch connected between the second power source and a load;

a safety circuit in electrical communication with the first electromagnetic latch and the second electromagnetic latch, the safety circuit comprising a plurality of loop connections and a plurality of serially connected safety stage circuits each comprising at least one switch relay configured to prevent an electrical connection between the first power source and the load and the second power source and the load simultaneously; and

a control circuit in communication with the safety circuit, the control circuit configured to provide one or more control signals comprising an OPEN signal to the first electromagnetic latch, an OPEN signal to the second electromagnetic latch, a latch select signal, and a CLOSED signal to the plurality of serially connected safety stage circuits of the safety circuit to control the operation of the first electromagnetic latch and the second electromagnetic latch;

wherein the at least one switch relay comprises a first status switch relay in electrical communication with the first electromagnetic latch and connected in series between the CLOSED signal from the control circuit and the second electromagnetic latch such that when the first electromagnetic latch is closed, the first status switch relay is open to prevent the CLOSED signal from being received at the second electromagnetic latch.

9. The automatic power transfer switch of claim 8 wherein the control circuit comprises a processor and at least one memory device storing one or more computer-implemented instructions that, when executed by the processor, cause the control circuit to provide one or more control signals to the safety circuit.

10. The automatic power transfer switch of claim 8 wherein the control circuit is in wireless communication with the safety circuit to provide the one or more control signals to the safety circuit wirelessly.

11. The automatic power transfer switch of claim 8 wherein the at least one switch relay further comprises:

a second status switch relay in electrical communication with the second electromagnetic latch and connected in series between the CLOSED signal from the control circuit and the first electromagnetic latch such that when the second electromagnetic latch is closed, the second status switch relay is open to prevent the CLOSED signal from being received at the first electromagnetic latch.

12. The automatic power transfer switch of claim 11 wherein the at least one switch relay further comprises:

a first select switch relay in electrical communication between the OPEN signal to the first electromagnetic latch and the first electromagnetic latch and a second select switch relay in electrical communication between the CLOSE signal and the first electromagnetic latch, wherein an asserted electromagnetic latch select signal from the control circuit operates to allow the first electromagnetic latch to receive the OPEN signal to the first electromagnetic latch and the CLOSE signal.

13. The automatic power transfer switch of claim 12 wherein the at least one switch relay further comprises:

a third select switch relay in electrical communication between the OPEN signal to the second electromagnetic latch and the second electromagnetic latch and a fourth select switch relay in electrical communication between the CLOSE signal and the second electromagnetic latch, wherein a de-asserted electromagnetic latch select signal from the control circuit operates to allow the second electromagnetic latch to receive the OPEN signal to the second electromagnetic latch and the CLOSE signal.

14. The automatic power transfer switch of claim 13 wherein the at least one switch relay further comprises:

a load first phase relay electrically connected to a first load phase busbar and connected in series between the CLOSED signal from the control circuit and the first electromagnetic latch and the second electromagnetic latch such that when the load first phase relay is energized by the first load phase busbar, the load first phase relay is open to prevent the CLOSED signal from being received at the first electromagnetic latch and the second electromagnetic latch.

15. The automatic power transfer switch of claim 14 wherein the at least one switch relay further comprises:

a load second phase relay electrically connected to a second load phase busbar and connected in series between the CLOSED signal from the control circuit and the first electromagnetic latch and the second electromagnetic latch such that when the load second phase relay is energized by the second load phase busbar, the second first phase relay is open to prevent the CLOSED signal from being received at the first electromagnetic latch and the second electromagnetic latch.

16. The automatic power transfer switch of claim 15 wherein the at least one switch relay further comprises:

a power status switch relay electrically connected to a power signal from the control board and connected in series between the CLOSED signal from the control circuit and the first electromagnetic latch and the second electromagnetic latch such that when the power status switch relay is energized by the power signal, the power status switch relay is closed to allow the CLOSED signal to be received at the first electromagnetic latch and the second electromagnetic latch.