Power bus on Passenger airliner?

[grizedale]

Hello,

What is the power bus voltage on a passenger airliner? (eg Airbus)

Is it DC or AC, and what magnitude and frequency?

 

[yura717]

Aircraft electrical components operate on many different voltages both AC and DC. However, most of the aircraft systems use 115 volts (V) AC at 400 hertz (Hz) or 28 volts DC. 26 volts AC is also used in some aircraft for lighting purposes. DC power is generally provided by “self-exciting” generators containing electromagnetics, where the power is generated by a commutator which regulates the output voltage of 28 volts DC. AC power, normally at a phase voltage of 115 V, is generated by an alternator, generally in a three-phase system and at a frequency of 400 Hz.

Higher than usual frequencies, such as 400 Hz, offer several advantages over 60 Hz – notably in allowing smaller, lighter power supplies to be used for military hardware, commercial aircraft operations and computer applications. As aircraft space is at a premium and weight is critical to aircraft engine thrust and fuel burn (and thus the aircraft range and engine horsepower per pound), 115 volts at 400 Hz offers a distinct advantage and is much better than the usual 60 Hz used in utility power generation.

 

[grizedale]

In cases where its 115VAC at 400Hz, it would be interesting to know whether or not they use Active Power Factor Correction in the SMPS's.......i would have thought so?

.....and from what power level would you need to use PFC, for a typical passenger airliner aircraft.