IBM 4331 Mainframe 3 phase converter

Paul Koning paulkoning at
Thu May 4 11:05:49 CDT 2017

kVA is simply kilovolts times amps.  It is roughly a synonym for kW, except that it probably ignores the phase angle.  So for resistive loads, kVA == kW but for inductive or capacitive loads, kVA would be larger.

1 hp == 746 W.  But when people talk about phase converter hp limits, they are looking not just at the steady state load but also at the startup peak current, which is a fairly substantial multiple of the steady state load.

For your application, you probably have some motor loads and possibly some others (power supplies).  If they are mostly motor loads, use the steady state kVA spec and convert that back to hp by dividing by 0.746.  Alternatively, if the converter has a rated steady state load, match that against the steady state power spec for the machine.  The peak current handling of the converter will take care of either motor startup peaks, or power supply inrush current.


> On May 4, 2017, at 10:36 AM, Guy Sotomayor Jr via cctalk <cctalk at> 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

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