Supercomputers, fishing for information

Jon Elson elson at
Tue Nov 8 20:18:20 CST 2016

On 11/08/2016 11:08 AM, Guy Sotomayor Jr wrote:
> I’m looking to have to do something to get 3-phase for the 
> IBM 4331 gear. I haven’t quite added up the power 
> requirements yet but I’m guessing its going to be in the 
> 10-15kVA range. Since the power to all of the gear is 
> really split between 3 loads (string of 4 3340 drives, 
> 3803 control unit + 2 3420 tape drives and 2821 control 
> uint + 1403 printer + 2540 card reader/punch) I need to 
> figure out if it’s best to have one big converter or 3 
> smaller ones. It’s unlikely that I’d be running all of the 
> peripherals at once. The 4331 itself runs off of single 
> phase 220v. TTFN - Guy 
This is tricky stuff.  Motor VFDs produce 400 V square waves 
of varying duty cycle, so unless you built a very good 
filter, you couldn't feed that to a a lot of these devices.  
Possibly you could rewire all that stuff to run the 
electronics off single-phase power, and use VFDs for the 
3-phase motors.  I know the tape drive vacuum blowers and 
1403 printer had 3-phase motors in them.  Likely the 3340's 
do, too.  I'm guessing some of those control units may have 
run off single-phase, with the supplies balanced across 
different phases.  That was fairly common for stuff that 
didn't draw massive amounts of power.  Sounds like QUITE a 


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