The IBM 7090 used a motor generator, IBM model 7618 apparently http://ed-thelen.org/comp-hist/7090-PowerSupplyControl&Distribution-223-6904.pdf Marc
> On May 4, 2021, at 5:03 PM, Jon Elson via cctalk <cctalk@classiccmp.org> > wrote: > > On 05/04/2021 06:06 PM, Donald via cctalk wrote: >> In the deep recesses of my mind I seem to remember something about S/360 >> machines using a motor generator. >> If I am right was this to create a stable power source at a certain >> frequency or voltage? > Nope. I know the 360/50 and 360/65 used a "converter-inverter" that > converted 208 3-phase > to about 280 V DC, then inverted it with a 4-SCR inverter feeding a resonant > transformer to > create 120 V 2.5 KHz regulated single-phase sine wave power. All the > critical loads in the CPU ran off this power. Notably, the I/O power > sequencer and console lamps power supply did not run off this power. The > converter-inverter made an absolutely HORRIBLE whine that could be heard 20+ > feet from the back of the CPU even in a very noisy machine room. > > The only "360" machine I know of that used 415 Hz was the Model 195, although > I can guess that > the 360/85 used 415 Hz also, as it was essentially the prototype of the > 370/165. > > The 370/145 used an internal motor/generator set in the back of the CPU > cabinet to produce 120 V 415 Hz 3-phase power. Larger 370's generally were > provided with UPS's instead of M/G sets to create the 415 Hz power. > > Also, the 709X series ran off 400 Hz from a motor/generator set. > > The 360/50 and /65, at least, were pretty sensitive to noise and short > dropouts in the mains supply. > The 370's with the MG sets rode through pretty severe power dips with no > effect at all, until the disk drives and tape drives went offline. > > Jon
