What is the standard frequency of the main aircraft AC power?

What is the standard frequency of the main aircraft AC power?

• A. 50 Hz
• B. 60 Hz
• C. 400 Hz
• D. 800 Hz

Answer: (C)

Aircraft electrical systems use a higher-frequency AC power to keep equipment lightweight and compact. The standard frequency is 400 Hz because it lets transformers, generators, and motors be much smaller and lighter for the same power, which is crucial in aviation where weight matters. Generators are designed to produce 400 Hz efficiently with practical engine RPMs, often using multi-pole machines and gear reductions to hit that speed. Lower mains frequencies like 50 Hz or 60 Hz would require larger magnetic cores and heavier hardware for the same power, increasing weight. A higher frequency such as 800 Hz could shrink components further, but it adds design challenges, reduces efficiency for many loads, and isn’t as broadly compatible with avionics and actuators, so it’s not the standard.

Aircraft electrical systems use a higher-frequency AC power to keep equipment lightweight and compact. The standard frequency is 400 Hz because it lets transformers, generators, and motors be much smaller and lighter for the same power, which is crucial in aviation where weight matters. Generators are designed to produce 400 Hz efficiently with practical engine RPMs, often using multi-pole machines and gear reductions to hit that speed.

Lower mains frequencies like 50 Hz or 60 Hz would require larger magnetic cores and heavier hardware for the same power, increasing weight. A higher frequency such as 800 Hz could shrink components further, but it adds design challenges, reduces efficiency for many loads, and isn’t as broadly compatible with avionics and actuators, so it’s not the standard.