Supercomputers, fishing for information

aswood at aswood at
Mon Nov 7 00:30:00 CST 2016

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 <elson at>:
>> On 11/06/2016 12:46 PM, Chuck Guzis wrote:
>> On 11/06/2016 09:18 AM, ethan at 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

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