A transformer rectifier powered from the No. 2 AC system provides emergency DC power to the which bus if both starter / generators are inoperative?

A transformer rectifier powered from the No. 2 AC system provides emergency DC power to the which bus if both starter / generators are inoperative?

• A. Battery Bus
• B. No 1 Main DC Bus
• C. No 2 Main DC Bus
• D. Both main DC Buses

Answer: (A)

The emergency power path uses a transformer rectifier that is fed from the No. 2 AC system to supply DC to the Battery Bus. When both starter and generators are inoperative, there is no source to feed the main DC busses, so the only limited, independent DC power available comes from this TR to the Battery Bus. Power on the Battery Bus keeps essential equipment and loads alive and, via the battery, helps sustain operation until power can be restored. The main DC busses themselves aren’t intended to be powered directly from this emergency path, which is why the correct choice is the Battery Bus.

The emergency power path uses a transformer rectifier that is fed from the No. 2 AC system to supply DC to the Battery Bus. When both starter and generators are inoperative, there is no source to feed the main DC busses, so the only limited, independent DC power available comes from this TR to the Battery Bus. Power on the Battery Bus keeps essential equipment and loads alive and, via the battery, helps sustain operation until power can be restored. The main DC busses themselves aren’t intended to be powered directly from this emergency path, which is why the correct choice is the Battery Bus.