On 07/26/2018 07:54 AM, Anders Nelson via cctalk wrote: > To get that power, did they have to use a rotary convertor from 60Hz > 3-phase to get 400Hz? > > https://en.wikipedia.org/wiki/Rotary_converter
As Paul mentioned, less a "rotary converter" than a AC motor-AC generator hookup. One advantage is that the rotational inertia in such a setup does have the ability to smooth over small power disruptions. Such MG setups were very common in industry before modern semiconductors. When I had a summer job showing movies at a drive-in theater (a long time ago), the supply for the carbon-arc lamps was a 40hp motor powered by 3-phase 60Hz, driving a DC generator. In WWII radio equipment, MGs in a unitzed form called "dynamotors" were used to supply the high-voltage anode voltage for the tubes. Electroplating shops similarly used large DC generator setups to supply plating current. 3 phase full-wave rectified AC has approximately 87% DC content at 6x the supply frequency. So for 400Hz, the ripple is only 13 percent at 2400 Hz before filtering. --Chuck
