After the engines are running, what powers the electrical buses?

After the engines are running, what powers the electrical buses?

• A. The standby inverter powers the main buses.
• B. External power remains the primary source.
• C. Batteries power the buses.
• D. Engine-driven generators supply the buses; TRUs convert AC to DC for DC loads.

Answer: (D)

When the engines are running, the engine-driven generators are the primary source feeding the electrical buses. They supply the AC power to the main and essential AC buses. The DC loads on the aircraft aren’t connected directly to that AC power; transformer-rectifier units take the AC from the generators and rectify it to DC to feed the DC buses and to charge the batteries. In short, engine-driven generators power the buses, with the TRUs converting that AC to DC for the DC system.

When the engines are running, the engine-driven generators are the primary source feeding the electrical buses. They supply the AC power to the main and essential AC buses. The DC loads on the aircraft aren’t connected directly to that AC power; transformer-rectifier units take the AC from the generators and rectify it to DC to feed the DC buses and to charge the batteries. In short, engine-driven generators power the buses, with the TRUs converting that AC to DC for the DC system.