What are the typical three-phase voltage and frequency values for large aircraft power systems?

What are the typical three-phase voltage and frequency values for large aircraft power systems?

• A. 3 phase 230/460 volts, 60 Hz
• B. Single phase 120V, 60 Hz
• C. 3 phase 277/480 volts, 60 Hz
• D. 3 phase 115/208 volts, 400 Hz

Answer: (D)

Aircraft power systems use three-phase, high-frequency power to keep equipment lighter and smaller while delivering the needed power. At 400 Hz, transformers and motors can be much smaller than at 50/60 Hz, which saves weight—critical on aircraft. The typical voltage is about 115 V line-to-neutral, giving roughly 208 V line-to-line in a three-phase system (often described as 115/208 V). This combination—three-phase, 115/208 V, 400 Hz—fits the needs of large aircraft loads, including avionics and motors, without the heft of lower-frequency or higher-voltage land-based standards. The other options either use single-phase power, or frequencies (60 Hz) and voltages (277/480 V, 230/460 V) not standard for large aircraft.

Aircraft power systems use three-phase, high-frequency power to keep equipment lighter and smaller while delivering the needed power. At 400 Hz, transformers and motors can be much smaller than at 50/60 Hz, which saves weight—critical on aircraft. The typical voltage is about 115 V line-to-neutral, giving roughly 208 V line-to-line in a three-phase system (often described as 115/208 V). This combination—three-phase, 115/208 V, 400 Hz—fits the needs of large aircraft loads, including avionics and motors, without the heft of lower-frequency or higher-voltage land-based standards. The other options either use single-phase power, or frequencies (60 Hz) and voltages (277/480 V, 230/460 V) not standard for large aircraft.