Which bus is powered by the transformer rectifier for emergency DC power when the No. 2 AC system supplies power?

Which bus is powered by the transformer rectifier for emergency DC power when the No. 2 AC system supplies power?

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

Answer: (A)

The transformer-rectifier used for emergency DC power feeds the Battery Bus. When No. 2 AC is supplying power, that AC is converted by the transformer-rectifier into DC and applied to the Battery Bus, providing emergency DC power to essential loads and supporting the battery charging path. The main DC buses are normally powered by their respective sources and are not the intended recipient of this emergency path from the transformer-rectifier. So the Battery Bus is the correct answer because it is the designated DC path for emergency power when the No. 2 AC system is active.

The transformer-rectifier used for emergency DC power feeds the Battery Bus. When No. 2 AC is supplying power, that AC is converted by the transformer-rectifier into DC and applied to the Battery Bus, providing emergency DC power to essential loads and supporting the battery charging path. The main DC buses are normally powered by their respective sources and are not the intended recipient of this emergency path from the transformer-rectifier. So the Battery Bus is the correct answer because it is the designated DC path for emergency power when the No. 2 AC system is active.