Why Airplanes Use 400 Hz Power – Monroe Aerospace News
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Why Airplanes Use 400 Hz Power

Why Airplanes Use 400 Hz Power

400 Hz has become the de-facto power frequency for airplanes. Most airplanes have either generators or alternators that produce power. When flying, an airplane’s generators or alternators will produce power that’s distributed to its various electrical devices and components. Rather than using the same 50 or 60 Hz frequency as standard wall outlets, though, airplanes use 400 Hz frequency power. Why do so many airplanes use 400 Hz power exactly?

The Basics of Aerospace Electrical Systems

Electrical systems play a key role in the function of modern-day airplanes. All airplanes contain a myriad of electrical devices and components, which require power to function. As previously mentioned, airplanes can generate power either by generators or alternators.

Airplanes can operate on a range of different power frequencies, some of which are alternating current (AC), whereas others are direct current (DC). With that said, most airplanes have an electrical system that specifically uses 400 Hz. That, of course, is substantially higher than the 50 or 60 Hz frequency used in standard wall outlets.

Lower Weight

One of the reasons why so many airplanes use 400 Hz power is because it allows for a lower weight. Weight is a critical factor in the design of an airplane. If an airplane is too heavy, it may not be able to take off. At the very least, it will require a more powerful engine or engines. Aerospace manufacturing companies can achieve a lower weight by using 400 Hz power.

With 400 Hz, airplanes require fewer generators or alternators to produce a sufficient amount of power. This reduces their total weight, thereby making it easier for airplanes to take off. If airplanes used a lower power frequency, they would require more generators or alternators, thus increasing their total weight.


Another reason why 400 Hz power has become so common is because it allows for the standardization of electrical devices and components. If airplanes were designed with electrical systems in different power frequencies, they wouldn’t have cross-compatible devices and components. Rather, some devices and components would be restricted to certain airplanes.

Using 400 Hz power ensures creates a standard for electrical devices and components. Since most airplanes use 400 Hz power, their devices and components can be easily replaced.

In Conclusion

When researching electrical systems used in airplanes, you’ll probably discover that most airplanes use 400 Hz power. It’s become the universal frequency for aerospace electrical systems. Airplanes use 400 Hz power because it reduces their total weight while also providing standardization of their electrical devices and components.