29/07/2023
Why is electricity different on aircraft?
In an aircraft, the voltage is about 200 volts.
The phase voltage is about 115 volts. The frequency is 400 hertz. So, an aircraft electrical system is said to be a 115V/200V/400Hz/3 phase system.
That is substantially higher than the 60 Hz frequencies used in standard household outlets. There are several reasons for this.
One of the reasons why so many airplanes use 400 Hz power is because it allows for a lower weight.
Higher frequency means smaller wire gauges throughout the aircraft. Another advantage or weight reduction comes from high-frequency alternators require fewer copper coils in order to generate the necessary electrical current.
This reduction in material allows the alternator to become much smaller such that it takes up less space and weighs much less than it would otherwise. In the design of an aircraft the common rule of thumb is that removing one pound of weight can actually reduce the overall weight by at least five pounds because of all the extra structure and fuel that is no longer required to carry that pound over the range of the plane.
Combined the reduction in weight means the plane needs less fuel to travel the same distance so that the aircraft is more economical to operate. Since saving weight is so important to reducing the costs of an airplane, the use of smaller and lighter 400 Hz electrical generators is a significant advantage over 60 Hz electrical systems. This is why it has become the standard in aircraft electrical systems.
