If all engines' generators are unavailable, which sources can energize the essential buses?

If all engines' generators are unavailable, which sources can energize the essential buses?

• A. Battery only
• B. APU generator or external power source
• C. Solar panels
• D. Hydraulic power unit

Answer: (B)

When all engine-driven generators are unavailable, essential buses must be powered by an alternate source capable of supplying the required electrical load. The reliable options in this situation are the APU generator or an external power source. Starting the APU provides electrical power similar to the engines, letting the essential buses stay energized on the ground or in flight if engine power is out. An external power source (ground power unit) can also supply this power without starting the APU. Battery power alone isn’t sufficient to energize the essential buses for normal operation, though it can provide limited power for brief needs or memory during start. Solar panels aren’t used to power the ERJ-145’s essential buses, and a hydraulic power unit does not generate electrical power.

When all engine-driven generators are unavailable, essential buses must be powered by an alternate source capable of supplying the required electrical load. The reliable options in this situation are the APU generator or an external power source. Starting the APU provides electrical power similar to the engines, letting the essential buses stay energized on the ground or in flight if engine power is out. An external power source (ground power unit) can also supply this power without starting the APU.

Battery power alone isn’t sufficient to energize the essential buses for normal operation, though it can provide limited power for brief needs or memory during start. Solar panels aren’t used to power the ERJ-145’s essential buses, and a hydraulic power unit does not generate electrical power.