IBM 4331 Mainframe 3 phase converter

jim stephens jwsmail at
Thu May 4 10:04:14 CDT 2017

On 5/4/2017 7:36 AM, Guy Sotomayor Jr via cctalk wrote:
> Does anyone know how to convert KVa to 208v 3-phase currents and/or HP?  IBM’s docs all specify power in KVa and most of the 3 phase converters (other than what Bob posted) seem to specify HP.  If I’m going to spend serious coin on a phase converter (I think I found it online for ~$3k…ouch!), I want to make sure it’s sized properly.
> Thanks.
> TTFN - Guy
You will also need to get the motor start information, or you will 
vaporize a phase converter.

Another possible approach that a friend is taking is to take three 
single phase identical UPS system and synch the phases of the three 
converter output circuits to proper three phase.

He's made up one from three junk APC units I've got.  I can forward info 
if you would like on this approach from him.  One thing that helps is he 
snagged and maintained the drawings of all of the APC and other output 
circuits over the years and has good info on how to pull this off.

The quadrature power will be something to deal with on your three phase 
loads, but you may be able to run quite a bit of single phase hardware 
directly off of the mains.


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