A system includes a first AC bus configured to supply power from a first generator. A second AC bus is configured to supply power from a second generator. An AC essential bus tie contactor (AETC) selectively connects between an AC essential bus and the first and second AC busses. An AETC controller is connected to switch the AETC between a first state connecting the AC essential bus to the first AC bus and a second state connecting the AC essential bus to the second AC bus. A sensor system is configured to detect at least one of delta current and overcurrent in the AC essential bus and in at least one of the first AC bus and the second AC bus. The sensor system is operatively connected to the AETC controller for switching the AETC between the first state and the second state based on input from the sensor system.