What is the purpose of an inverter in an aircraft power system?

• A. To regulate the 28V DC bus
• B. To charge the battery
• C. To provide DC power to avionics
• D. To convert DC (from the 28V bus) to AC to power equipment that requires AC power when AC power is unavailable

Answer: (D)

An inverter in an aircraft power system converts DC from the 28V bus into AC so equipment that needs AC can run when AC power isn’t available. This lets essential avionics and other AC-powered loads operate off the battery or DC source during generator or electrical faults, using the standard aircraft AC distribution (typically 115V at 400 Hz). The other options don’t fit because regulating the DC bus is done by DC regulators, charging the battery is the job of a charger, and providing DC power to avionics comes from the DC bus, not from converting DC to AC.