The Convex C38xx as well the Fujitsu VPP used isolation transformers. Luckily I was able to save the Transformer for my C3880.
> Am 06.11.2016 um 19:57 schrieb Jon Elson <el...@pico-systems.com>: > >> On 11/06/2016 12:46 PM, Chuck Guzis wrote: >> On 11/06/2016 09:18 AM, et...@757.org wrote: >>>> But smaller than the Crays of the era. If it doesn't run on 400Hz, >>>> it's a 'mini' supercomputer. >>> Hmmm I knew the earlier Crays often had motor generator setups and >>> such but I thoght that was just for power filtering and maybe >>> flywheels for ups setups. Didn't know they were 400hz! Odd! >> Not at all--that goes back at least to the 1960s. Consider the CDC >> mainframes--MG sets providing 3-phase 400Hz power to variac-regulated >> 3-phase fullwave rectifier setups. The ripple frequency is 2400Hz and >> has a very high DC component. >> >> > All 370's ran off 415 Hz 3-phase power. The mid-sized ones had the > motor-generator set built into the back of the machine. The 415 Hz > (regulated) power was transformed to low voltage and run through an > inductor-input filter and then series pass regulated. They had a circuit > they called an "electronic capacitor" that pulled extra current through the > inductor during the voltage peaks, so the inductor carried enough current > during the voltage valleys. This reduced the ripple current on the capacitor > banks. > > The 360s ran off single-phase 120 V 2500 Hz power, produced by a > "converter-inverter" unit in the back, that converted utility 3-phase power > to DC, then inverted it with an SCR inverter. This made the DC power > supplies in the machine quite small. Since they ran off regulated 2500 Hz > power, they dropped only a very small voltage across the series-pass > transistor. > > Jon > >
