If the GPU is not connected, which condition energizes DC buses on the ground?

If the GPU is not connected, which condition energizes DC buses on the ground?

• A. At least one generator online with SHED BUSES knob set to OVRD
• B. APU must be running
• C. Battery 1 must be connected
• D. Backup battery charging

Answer: (A)

When the GPU isn’t connected, the DC buses on the ground are powered only if a live generator is supplying them and the bus-shed system is overridden so the buses stay connected. Having at least one generator online (engine-driven or APU) provides the electrical source, and setting the SHED BUSES control to OVERRIDE prevents automatic shedding from disconnecting the DC buses. This combination ensures the DC buses are energized without the GPU. Relying on a battery alone or on charging the backup battery doesn’t provide full DC bus power, and simply having the APU running doesn’t guarantee energizing the buses unless the OVERRIDE setting is used.

When the GPU isn’t connected, the DC buses on the ground are powered only if a live generator is supplying them and the bus-shed system is overridden so the buses stay connected. Having at least one generator online (engine-driven or APU) provides the electrical source, and setting the SHED BUSES control to OVERRIDE prevents automatic shedding from disconnecting the DC buses. This combination ensures the DC buses are energized without the GPU. Relying on a battery alone or on charging the backup battery doesn’t provide full DC bus power, and simply having the APU running doesn’t guarantee energizing the buses unless the OVERRIDE setting is used.