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RE: ups (uninterrupted power supply) questions?

To: "shop-talk" <shop-talk@autox.team.net>
Subject: RE: ups (uninterrupted power supply) questions?
From: "Randall" <tr3driver@comcast.net>
Date: Sun, 20 Mar 2005 00:09:35 -0800
> the i.s.c. guy at the
> wife's office recommended a u.p.s. as sort of un uber-surge protector,

That's a common misconception, Scott, but the truth is that for the vast
majority of UPS, the power supply does not come into action until the power
actually fails.  Until then, they just pass the mains power through, hopefully
with some sort of surge protection on it.

> will a u.p.s. (or at least do some kinds of them) function like a surge
> protector?

Yes, most of them do have surge protection in addition to the UPS function.

>  is it worth using it as one?  the only thing I'd use the
> extended power for is just to get to the computer to shut it down
> normally, otherwise everything else could go off whenever.

My suggestion would be to use an UPS for the computer then (but not the laser
printer if you have one), and just quality surge protector(s) for everything
else.  APC even sells a "whole house" surge protector that goes in your
electrical panel (but they require you to have an electrician install it, which
may be expensive).

> can I get one (large) u.p.s. and wire everything I want
> protected into it?

Yes, but you can expect to spend some major money on an UPS that big.

>  am I better off just buying the best surge
> protectors I can find, and if so, how 'bout brand names and
> recommendations?

I would recommend APC as a source for both surge protection and UPS.
http://www.apcc.com/

They've been around for a long time, and have accumulated an impressive
reputation for making quality equipment even at the lowest consumer level.  Back
when I was head of IT, we had lots of UPS and tried various brands ...
eventually settled on APC and our UPS problems went away.  Still have to change
batteries occasionally, but otherwise the equipment just worked.  My current
employer uses them too, as well as the last hospital I was in.

> and if you know of a cable protector, do tell.

APC offers several of them, generally integrated with other types of surge
protection.

> I'm told (by the cable co.) that you
> can't surge protect the co-ax because it will degrade the signal too
> much for the modem.

Did he look like Jim Carey ?  Simply not true.

> and if I can use the u.p.s., any help with sizing, brands, etc.?  I know
> wayyyy to little for the stuff I googled to be any use so far.

There are two aspects to consider with an UPS, power (volt-amps) and run-time.
APC's web site has calculators to help you with selecting for computers (and
maybe other things, I didn't check).  But in general, you can check the name
plate for the maximum current the device draws (in amps), and multiply that by
the nominal line volts to get volt-amps.  Add it up for all the devices you plan
to power on this UPS, then add at least 15-20% for safety margin.  If the list
includes anything with a substantial motor in it (like a refrigerator), then add
at least 50% of that device's requirement.  Always best to be conservative here,
as you sure don't want to find out you've got too much load when the power
fails.

Most UPS have a fairly short run-time in their base configuration (if you load
them close to their VA ratings).  But some of them allow you to add more
batteries to extend the run-time, which might be needed for things like
telephones.  You can also get a computer interface that will shut the computer
down gracefully when the UPS gets close to the end of it's run-time, even if the
computer is unattended.

If you want absolutely the best surge protection possible, then look for an
"on-line" UPS.  They take the incoming AC and convert it to DC, to charge the
batteries and to power the output DC-AC converter, all the time.  But, they're
expensive to run, as they waste at least 20-25% of the power; and tend to be
noisy and expensive to purchase.  Also generate a lot of heat (due to all the
wasted power).  And they're overkill for household electronics, IMO.

HTH
Randall






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