Originally Posted by
gordonroxburgh
The flight control inverters were the 26V AC power supplies for the flying controls working (from memory) at 1500Hz rather than the normal 400Hz.
There are people on here far more qualified, but i believe using the much higher frequency all but ruled out interference from any other aircraft system for the control signalling to the flight control surfaces
Gordon is right: the flight control inverters converted the 28V DC aircraft supply to the 26V AC 1800Hz that supplied the flying controls.
And the 1800Hz was chosen because it's halfway between the 4th and 5th harmonic of 400Hz, so yes, it minimised interference of the 400Hz main AC supply in the flying control system.