Which AC buses become energized after the RAT deploys?

When the Ram Air Turbine (RAT) deploys, it serves as an emergency power source for the aircraft's electrical systems. In the Embraer Regional Jet system, the RAT is designed to provide power to essential systems when there is a loss of engine-driven generators.

The correct answer indicates that both the AC ESS (Essential) Bus and the AC STBY (Standby) Bus become energized upon RAT deployment.

The AC ESS Bus powers critical components that are necessary for the safe operation of the aircraft, including flight control systems, essential cockpit displays, and communication systems. The AC STBY Bus provides power to additional backup systems, ensuring that there is redundancy for key flight functionalities.

This dual energization maximizes the aircraft's operational reliability in the event of generator failure, allowing pilots to maintain control and responsiveness in critical situations. Understanding these power distribution systems is vital for crew training and safe aircraft operation.