Static transfer switches with intelligent bypass

1 . A static transfer switch comprising:

first and second inputs, the first input configured to selectively couple with a first power source via a first circuit breaker, and the second input configured to selectively couple with a second power source via a second circuit breaker;

an output configured to couple with a load;

first and second bypass breakers, the first bypass breaker configured to selectively couple only the first input directly with the output, and the second bypass breaker configured to selectively couple only the second input directly with the output, wherein a first bypass connection comprising the first input, the first bypass breaker, and the output, does not include any additional elements configured to interrupt an electrical current flowing therethrough, and wherein a second bypass connection comprising the second input, the second bypass breaker, and the output, does not include any additional elements configured to interrupt an electrical current flowing therethrough;

first and second power stages each comprising at least one solid-state switch configured to:

conduct electrical power when a respective power stage is in an active state; and

block the electrical power when the respective power stage is in an inactive state;

first and second contactors, the first contactor configured to selectively couple the first input with the first power stage, and the second contactor configured to selectively couple the second input with the second power stage;

a load switch configured to selectively couple the first and second power stages with the output, wherein the first and second power stages are configured to selectively couple the first and second contactors with the load switch, respectively, when in the active state; and

a controller configured to modify an operating state of the first and second contactors and the active/inactive state of the first and second power stages.

2 . The static transfer switch of claim 1 , wherein:

the first and second circuit breakers are closed, the first and second bypass breakers are open, the first power stage is active, the second power stage is inactive, the first and second contactors are closed, and the load switch is closed, and

the controller is further configured to determine whether the second circuit breaker has opened; and

in response to determining that the second circuit breaker has opened, the controller is further configured to:

open the second contactor; and

release a lock on the first bypass breaker.

3 . The static transfer switch of claim 2 , wherein the controller is further configured to:

cause the first bypass breaker to close; and

lock the second circuit breaker in an open position.

4 . The static transfer switch of claim 3 , wherein the controller is further configured to:

deactivate the first power stage;

open the first contactor; and

cause the load switch to open.

5 . The static transfer switch of claim 1 , wherein:

the first circuit breaker is closed, the second circuit breaker is open, the first bypass breaker is closed, the second bypass breaker is open, the first and second power stages are inactive, the first and second contactors are open, and the load switch is open, and

the controller is further configured to:

receive a command to perform an un-bypass operation for the static transfer switch; and

cause the load switch to close in response to receiving the command to perform the un-bypass operation for the static transfer switch.

6 . The static transfer switch of claim 5 , wherein the controller is further configured to:

activate the first power stage; and

close the first contactor.

7 . The static transfer switch of claim 6 , wherein the controller is further configured to:

cause the first bypass breaker to open; and

release a lock on the second circuit breaker.

8 . The static transfer switch of claim 7 , wherein the controller is further configured to:

cause the second circuit breaker to close;

lock the first bypass breaker open; and

close the second contactor.

9 . The static transfer switch of claim 5 , wherein the controller is further configured to:

determine whether a power quality of the first power source is outside of a pre-defined range; and

block the un-bypass operation from being performed in response to determining that the power quality of the first power source is outside of the pre-defined range.

10 . The static transfer switch of claim 1 , wherein:

the first and second circuit breakers are closed, the first and second bypass breakers are open, the first power stage is inactive, the second power stage is active, the first and second contactors are closed, and the load switch is closed, and

the controller is further configured to determine whether the first circuit breaker has opened; and

in response to determining that the first circuit breaker has opened, the controller is further configured to:

open the first contactor; and

release a lock on the second bypass breaker.

11 . The static transfer switch of claim 10 , wherein the controller is further configured to:

cause the second bypass breaker to close; and

lock the first circuit breaker in an open position.

12 . The static transfer switch of claim 11 , wherein the controller is further configured to:

deactivate the second power stage;

open the second contactor; and

cause the load switch to open.

13 . The static transfer switch of claim 10 , wherein:

the first circuit breaker is open, the second circuit breaker is closed, the first bypass breaker is open, the second bypass breaker is closed, the first and second power stages are inactive, the first and second contactors are open, and the load switch is open, and the controller is further configured to:

receive a command to perform an un-bypass operation for the static transfer switch; and

cause the load switch to close in response to receiving the command to perform the un-bypass operation for the static transfer switch.

14 . The static transfer switch of claim 13 , wherein the controller is further configured to:

activate the second power stage; and

close the second contactor.

15 . The static transfer switch of claim 14 , wherein the controller is further configured to:

cause the second bypass breaker to open; and

release a lock on the first circuit breaker.

16 . The static transfer switch of claim 15 , wherein the controller is further configured to:

cause the first circuit breaker to close;

lock the second bypass breaker open; and

close the first contactor.

17 . The static transfer switch of claim 13 , wherein the controller is further configured to:

determine whether a power quality of the second power source is outside of a pre-defined range; and

block the un-bypass operation from being performed in response to determining that the power quality of the second power source is outside of the pre-defined range.

18 . A static transfer switch comprising:

first and second inputs, the first input configured to selectively couple with a first power source via a first circuit breaker, and the second input configured to selectively couple with a second power source via a second circuit breaker;

an output configured to couple with a load;

first and second bypass breakers, the first bypass breaker configured to selectively couple the first input with the output, and the second bypass breaker configured to selectively couple the second input with the output;

first and second power stages configured to conduct electrical power when active;

first and second contactors, the first contactor configured to selectively couple the first input with the first power stage, and the second contactor configured to selectively couple the second input with the second power stage;

a load switch configured to selectively couple the first and second power stages with the output; and

a controller configured, in response to the first and second circuit breakers being closed, the first and second bypass breakers being open, the first power stage being active, the second power stage being inactive, the first and second contactors being closed, and the load switch being closed, to:

determine whether the second circuit breaker has opened; and

in response to determining that the second circuit breaker has opened, to:

open the second contactor;

release a lock on the first bypass breaker;

close the first bypass breaker;

lock the second circuit breaker in an open position;

deactivate the first power stage;

open the first contactor; and

open the load switch.

19 . The static transfer switch of claim 18 , wherein:

the controller is further configured, in response to the first circuit breaker being closed, the second circuit breaker being open, the first bypass breaker being closed, the second bypass breaker being open, the first and second power stages being inactive, the first and second contactors being open, and the load switch being open, to:

receive a command to perform an un-bypass operation for the static transfer switch; and

in response to receiving the command to perform the un-bypass operation, to:

close the load switch;

activate the first power stage;

close the first contactor;

open the first bypass breaker;

release a lock on the second circuit breaker;

close the second circuit breaker;

lock the first bypass breaker open; and

close the second contactor.

20 . The static transfer switch of claim 19 , wherein the controller is further configured to:

determine whether a power quality of the first power source is outside of a pre-defined range; and

block the un-bypass operation from being performed in response to determining that the power quality of the first power source is outside of the pre-defined range.