Gunther,
be careful with the return line: if you are running three different
phases, these are phase-shifted 120 degree against each other, so the
current maximum on each phase will occur at a different time, and the
center ("ground") line will not need to carry any current at all (in a
perfectly balanced circuit). If balance is not perfect, the ground wire
will have to bear at most the same load as any of the live wires.
If you feed a single phase into the same circuit on all three lines, you
will have peak current on all three "live" lines at the same time, and
the "ground" line will need to handle that. If it's not made to that
spec, you'll overload it by a factor of 3...
I don't think this is true for VAX power supplies, but I have heard
about process automation computers that are fed with three phases just
to make the period shorter and to use smaller capacitors. With this kind
of power supply, you'd get a lot of ripple on the DC output.
Regards,
Andreas
Gunther Schadow wrote:
>
> Hi,
>
> just to be sure, I would simply put all three phases on the
> same single phase. Are there any problems with that? The
> VAX 6000 is much pickier, but the VAX 11 and everything
> having the simple power distribution box should be fine,
> right?
>
> thanks,
> -Gunther
>
> --
> Gunther Schadow, M.D., Ph.D. gschadow_at_regenstrief.org
> Medical Information Scientist Regenstrief Institute for Health Care
> Adjunct Assistant Professor Indiana University School of Medicine
> tel:1(317)630-7960 http://aurora.regenstrief.org
--
Andreas Freiherr
Vishay Semiconductor GmbH, Heilbronn, Germany
http://www.vishay.com
Received on Fri Feb 01 2002 - 06:11:20 GMT