26 Jul
2018
26 Jul
'18
8:14 a.m.
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