6 Nov
2016
6 Nov
'16
10:57 a.m.
On 11/06/2016 12:46 PM, Chuck Guzis wrote:
On 11/06/2016 09:18 AM, ethan at 757.org wrote:
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
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!