Richard Welty [mailto:rwelty@suespammers.org] wrote:
>
> actually, for any really serious installation, i generally
> advise my clients to hire a professional engineering consultant
> who does generator/UPS setups for a living. it's way too easy
> to undersize these things and screw yourself.
>
> richard
> ("you mean we have to have power for the lights and the A/C too?")
I've done the really big UPSs for large computer installations - you
know, the ones where the UPS sits in four full size cabinets and is
powered by 480 Volt 3 phase. In those cases, the Voltage, Amps, Watts,
and BTU requirements were easy to determine (the manufacturers all
readily provided the info).
For this case, I'm trying to size the smaller rack mount type of UPS
to power a rack of 8 small servers. The problem is that the UPSs are
rated by VoltAmps, and the only info I can get on the servers is Watts.
I'm going to need several of the rack mounted UPSs to spread the load
as there is no room in the facility for a separate large UPS. I also
need to make the set up "redundant" to power the redundant power supplies
in the servers (each of a server's two power supply connected to a
different UPS). It's not that much of a problem except that I also
have to power things from standard 120V-20Amp power circuits because
the cost of running additional power circuits is excessive (and a long
lead time task).
I'm trying to get hold of the vendors technical people to determine
the actual Amps (or VA) requirements - in the mean time, I think that
it's the .707 factor (for the RMS) that I was looking for...
As for the lights and A/C - been there, done that. The lights
are usually provided by the facilities, but they always seem to
forget the emergency lighting...
The one other thing that usually gets forgotten is the "Emergency
Off" circuits. I've had the pros outfit the computer room with
fire detection systems that kill all power to the room. However,
they usually seem to forgot to provide a method to shut down the
UPS along with the other power - power TO the UPS, yes; power
FROM the UPS, no...
Thanks for all the input...
Tim Mullen
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