Fire Detection is powered by which bus?

Fire Detection is powered by which bus?

• A. Battery bus
• B. DC emergency bus
• C. DC main bus
• D. AC bus

Answer: (A)

Fire detection must stay powered even if the rest of the aircraft’s power system fails, so it’s tied to a source that remains energized under fault conditions—the battery bus. The battery bus is powered directly from the aircraft’s batteries, providing a reliable, independent supply to the fire-detection control unit and sensors when generators or the main power bus are unavailable. The DC main bus carries normal operating loads and can be lost during faults, so it isn’t guaranteed to stay powered. The DC emergency bus is reserved for critical systems during loss of power, but keeping fire detection on the battery bus ensures continuous operation in all power-loss scenarios. The AC bus handles alternating-current equipment, which isn’t part of the fire-detection circuit.

Fire detection must stay powered even if the rest of the aircraft’s power system fails, so it’s tied to a source that remains energized under fault conditions—the battery bus. The battery bus is powered directly from the aircraft’s batteries, providing a reliable, independent supply to the fire-detection control unit and sensors when generators or the main power bus are unavailable. The DC main bus carries normal operating loads and can be lost during faults, so it isn’t guaranteed to stay powered. The DC emergency bus is reserved for critical systems during loss of power, but keeping fire detection on the battery bus ensures continuous operation in all power-loss scenarios. The AC bus handles alternating-current equipment, which isn’t part of the fire-detection circuit.