Solid-state breaker coordination with downstream electromechanical breakers

A method operable by a solid-state circuit breaker for current-limiting a fault current during an electrical fault, wherein:

• the solid-state circuit breaker comprises:
• an input configured to connect to a source;
• an output configured to connect to a first load via a first electromechanical breaker and a second load via a second electromechanical breaker;
• a solid-state switch selectively coupling the input with the output;
• and
• a protection circuit communicatively coupled with the solid-state switch and configured to open the solid-state switch in response to the fault current exceeding an overcurrent protection threshold for the solid-state switch, and
• wherein the method comprises:
• determine whether a current through the solid-state switch reaches a pre-defined current threshold that is less than the overcurrent protection threshold;
• in response to determining that the current through the solid-state switch reaches the pre-defined current threshold, operate the solid-state switch in a discontinuous current conduction mode during an electrical fault to current-limit the fault current to less than the pre-defined current threshold for the solid-state switch to prevent the protection circuit from opening the solid-state switch and enable one of the first and second electromechanical breakers to trip and isolate the electrical fault;
• and
• adjusting a time during the discontinuous current conduction mode that the current through the solid-state switch is zero based on a type of the first and second electromechanical breakers.

A static transfer switch configured to current-limit a fault current during an electrical fault, the static transfer switch comprising:

• first and second inputs configured to couple with first and second power sources, respectively;
• an output configured to couple with at least a first load via a first electromechanical breaker and a second load via a second electromechanical breaker;
• first and second power stages configured to conduct electrical power when active, wherein the first power stage is configured to selectively couple the first input with the output, and wherein the second power stage is configured to selectively couple the second input with the output;
• at least one protection circuit configured to deactivate one of the first and second power stages in response to the fault current exceeding an overcurrent protection threshold for the first and second power stages;
• and
• a control circuit communicatively coupled with the first and second power stages and configured to:
• determine whether a current through the first or second power stages reaches a pre-defined current threshold that is less than the overcurrent protection threshold;
• in response to determining that the current through the first or second power stages reaches the pre-defined current threshold, operate one of the first and second power stages in a discontinuous current conduction mode during an electrical fault to current-limit the fault current to less than the pre-defined current threshold for the first and second power stages to prevent the at least one protection circuit from deactivating one of the first and second power stages until one of the first and second electromechanical breakers trips and isolates the electrical fault;
• and
• adjust a time during the discontinuous current conduction mode that the current through one of the first and second power stages is zero based on a type of the first and second electromechanical breakers.