VAXen at home

[Chuck Guzis]

On 19 Oct 2007 at 13:33, William Donzelli wrote:

> With older gear, why not? Most of that classic mainframe stuff has
> brute force power supplies, often fed by voltage regulating
> transformers (almost always a Sola, it seems).
> 
> The three phase motors in the drives will just help things along, as well.

My experience with these things (admittedly only with machine tools) 
shows a strong tendency for less-than-perfect (i.e. 120 degree) phase-
to-phase relationships and fairly drastic phase-to-phase voltage and 
current variations.  They work with motors, but none allows for full 
motor nameplate loading (usually around 80 percent of nameplate).  My 
take is that they work "sort of".  Heaven only knows how a power 
supply would behave attached to one of these things.

My feeling is that if you have to power some three-phase big iron 
from a single-phase source, it's probably better to take a look at 
one of the modern (and expensive) solid-state converters--or get some 
real three-phase distribution installed.

Cheers,
Chuck