Thoughts, tips, suggestions on what UPS to use?

[Gene E. Bloch]

Mike,

The Kill-A-Watt will measure VA or Watts and also power factor in
addition to volts and amps. IIRC the circuit is from an Analog Devices
application note. Some fellow put up his comparison of this device
against a current probe, Tek scope and HP meter. It was pretty close
for all practical purposes. It self powers from the source which is
why it doesn't like stepped approximations of sine for volts which can
burn up the internal supply.

bobs

Bob Smith
BS Studios
we organize chaos
http://www.bsstudios.com

The Kil-A-Watt also will accumulate KWH (kilowatt hours), which I find
useful, such as if you have a computer that is sometimes sleeping and
sometimes running - or a device like a refrigerator, which also is only
on part-time.

 

[Mogens V.]

I agree with all of Joe's point. In addition, factor in that the
batteries need to be replaced; APC usually recommend it after 4 years,
IIRC. The replacement battery is likely to cost 60 - 75% of that of
the UPS itself. Of course you can just let them grow old, and test
them from time to time to see whether they still have enough capacity,
but they do tend to become unreliable, and will eventually be a
greater liability than the risk of a power cut - exactly what they're
supposed to be protecting you from.

If you want to be able to work for an hour without power, look at
buying a laptop. Hopefully there's one out there that you can fit a
second battery pack to, without having to remove the CD/DVD drive to
do so. It's probably going to be cheaper than the UPS you'll need to
achieve the same with your desktop PCs.

Generally, a UPS allowing real work during an outage is mostly
unrealistic, except for labtops, or with a serious price premium.

Main role of a UPS is to maintain power for the few minutes outages
usually lasts (location and provider quality/stability dependant, of
cause), and to automatically shutdown the gear to prevent damage.
Your computers are somewhat old and likely subject to near future
substitution, which you may want to take into consideration.

However, you're using the gear for audio/video, and I've seen comments
to noise generated by the USP onto the ac grid behind it.
Maybe using power conditioners on all gear is the solution.

I can't verify either, and need info on this myself. Comments needed..

 

[Doc]

Take the nameplate ratings off of everything you want to plug into the UPS.
That's both computers, the monitors, whatever external disk drives you
might have, etc. Tote the power values all up.

Spoonfeeding needed. For example, one external drive says "Power - 12V
2A" is that what you're referring to? Am I adding up the volts or the
amps? Or both?

 

[Scott Dorsey]

Spoonfeeding needed. For example, one external drive says "Power - 12V
2A" is that what you're referring to? Am I adding up the volts or the
amps? Or both?

It should say 120V, 2A.

That means 120 X 2 = 240 VA.

Add up the VA ratings and compare them with the VA rating on the UPS inverter.
The UPS will also have a watt-hour rating.

If you have a 1200 WH unit, and a 240 VA load, you can expect it to run
five hours with just that disk drive and nothing else on it.

Watts aren't the same as volt-amps, but with typical computer gear they
will be within 50%.
--scott

 

[William Sommerwerck]

Spoonfeeding needed. For example, one external drive says

It should say 120V, 2A.
That means 120 X 2 = 240 VA.

Actually, I think 12V is correct. A drive doesn't draw 240VA.

I think the OP is looking at the drive case itself, not the wall wart that
powers it.

 

[Don Pearce]

Generally, a UPS allowing real work during an outage is mostly
unrealistic, except for labtops, or with a serious price premium.

Main role of a UPS is to maintain power for the few minutes outages
usually lasts (location and provider quality/stability dependant, of
cause), and to automatically shutdown the gear to prevent damage.
Your computers are somewhat old and likely subject to near future
substitution, which you may want to take into consideration.

However, you're using the gear for audio/video, and I've seen comments
to noise generated by the USP onto the ac grid behind it.
Maybe using power conditioners on all gear is the solution.

I can't verify either, and need info on this myself. Comments needed..

My experience of UPS is mainly third world. There, its purpose is to
span the few minutes between the power going off and somebody firing
up the diesel genny.

d

 

[Arny Krueger]

I've got two computers - a PIV and a PIII that share a
monitor. I use them primarily for doing audio/video.

How much UPS would I need to protect and keep both
computers going in the event of a short brown out or
power loss or keep them running at least long enough to
shut things down if it looks like the power is going to
be off for a while.

What is "a while" in minutes?

I've seen where there are issues with the type of power
that comes out of some UPS units. Are any of the units
at Best Buy/Circuit City - such as the APC brand - any
good?

They are good enough for their intended purpose, which may or may not be
what you have in mind.

What are important features to look for?

Primarily, enough capacity to keep your computers running for "a while".

These
various units have charts indicating how long they should
power a computer, but I don't know how realistic they
are.

The specs are probably realistic, as long as the internal batteries are in
good shape.

On the other end, how much unit would I need to keep a
computer going for say an hour if I were doing some
rendering of a DVD and didn't want to start over.

Consult the specs. Key to this is knowing the actual power drain of your
computers while they are doing the job you have. I'd recommend a small
investment ($30) in a little device called a "Kill-o-watt", to get some
actual numbers.

I usually turn off the monitor when rendering video, it's
my understanding the monitor is a big power hog.

That's right. Things like video monitors and laser printers are good things
to run direct off the power line, and not off the UPS.

 

[Doc]

It should say 120V, 2A.

Says "Power - DC Adapter 12V 2A"

 

[Scott Dorsey]

Actually, I think 12V is correct. A drive doesn't draw 240VA.

I think the OP is looking at the drive case itself, not the wall wart that
powers it.

If he's got drive enclosures with wall warts, he has even worse reliability
problems to worry about.
--scott

 

[Scott Dorsey]

Says "Power - DC Adapter 12V 2A"

Oh, that IS one of the crappy ones with the external power supply. That's
not all that useful... you want the input current numbers on the external
power supply. Or alternately you want to replace that with a more reliable
enclosure with an internal power supply...
--scott

 

[Doc]

All of the cheap standby units you describe produce lousy waveforms, but
you don't care about that since they're only running on inverter when the
power goes out.

That's another issue, I'm told that units that produce a "square"
waveform can actually damage components over time. Is this what all
the Best Buy/Circuit City type units produce? I assume there are
those that don't?

Also, I'm told there are some where the Computer runs off the unit
constantly and some where the unit only comes "online" when needed.

For example, the salesman at Cheap Guys where they currently have this
Ultra ULT31502 for $79.99

http://tinyurl.com/2r3e57

and he says it's the type where it constantly supplies power to the
computer. What about APC units like this one?

http://tinyurl.com/35ncvg


Assuming what he told me is correct, are there any inherent benefits/
problems with whether the computer is constantly running off the
battery as opposed to an "online only when needed" configuration?
Again, wondering about damage to the computer.

I like the readout on the APC case, but if one is superior at what
it's supposed to do, that's what I'd be most interested in. If the
battery is replaceable that would be great too. Even if you're only
saving 40% over the cost of a new unit, it's still 40%.

Thanks

 

[Scott Dorsey]

That's another issue, I'm told that units that produce a "square"
waveform can actually damage components over time. Is this what all
the Best Buy/Circuit City type units produce? I assume there are
those that don't?

It's not as bad as a square wave, but it's close. But you don't care,
since it's a standby unit and only running off inverter when the power
goes off.

Also, I'm told there are some where the Computer runs off the unit
constantly and some where the unit only comes "online" when needed.

Everything in your price range is going to be a standby unit. If you
DO buy an online unit, you will need one that produces a nice low distortion
waveform, and that is expensive.

For example, the salesman at Cheap Guys where they currently have this
Ultra ULT31502 for $79.99

http://tinyurl.com/2r3e57

and he says it's the type where it constantly supplies power to the
computer.

This is a "line interactive" unit, which means it's a cheap standby unit
with some additional voltage regulation. That additional regulation could
turn into a noise problem, but it might also be fine. This is not a real
online UPS.

What about APC units like this one?
http://tinyurl.com/35ncvg

This is basically the same way.

Assuming what he told me is correct, are there any inherent benefits/
problems with whether the computer is constantly running off the
battery as opposed to an "online only when needed" configuration?
Again, wondering about damage to the computer.

You will not find a real online UPS at Best Buy, and you will not find one
that can produce a good enough waveform to run audio gear unless you up
your price by about two orders of magnitude.

But you don't care about that anyway, since you only want a UPS to keep
the computer from crashing during a power outage, and the cheapest of the
cheapies will do that nicely enough.

I like the readout on the APC case, but if one is superior at what
it's supposed to do, that's what I'd be most interested in. If the
battery is replaceable that would be great too. Even if you're only
saving 40% over the cost of a new unit, it's still 40%.

All of these units are cheapies, none of them are particularly well-built
or sturdy, but they will all be fine for what you want. Note that with
something in this price range, you'll be using gel cells and you should
expect to replace them about every two years for a cost that is maybe half
the cost of the total unit.
--scott

 

[kony]

However, you're using the gear for audio/video, and I've seen comments
to noise generated by the USP onto the ac grid behind it.
Maybe using power conditioners on all gear is the solution.

I can't verify either, and need info on this myself. Comments needed..

Any decent audio gear should be immune to noise on the AC
lines. It can't be built with the assumption the AC power
is a perfect/clean sine wave without an UPS present since
that would already be unrealistic. Even subcircuits within
the same gear will generate noise that must (/should/) be
rejected by the other subcircuits (one way or another).

If the gear can't handle that, IMO it should just be
replaced or the flaws fixed. At that point if it is felt
there is still room for improvement, rather than a general
power conditioner look into something specific, "Balanced
Power". http://www.equitech.com/faq/faq.html

 

[kony]

Oh, that IS one of the crappy ones with the external power supply. That's
not all that useful... you want the input current numbers on the external
power supply. Or alternately you want to replace that with a more reliable
enclosure with an internal power supply...
--scott

These kinds of numbers are seldom useful for a couple of
reasons.

1) Input power to a supply is typically rated based on the
peak capacity of the supply, not on the load it's actually
powering which, unless the product is very questionably
designed, will be well below the peak PSU rating.

2) It doesn't account for peak current upon startup in all
aspects. Maybe it would for an external drive to spin up,
but to charge the supply filter capacitors is unlikely
(never spec'd in general) and even if the device were
already running there would still be a slight surge current
during the few ms between which the AC mains was switched
out and the UPS inverter switched in and stabilizing (unless
the UPS is an online unit).

Generally a conservative estimate might be a 2A spinup
current for the drive, 500mA 5V power, and 70% efficiency
from the PSU, about 38VA - though much lower in it's typical
running state.

 

[Scott Dorsey]

Any decent audio gear should be immune to noise on the AC
lines. It can't be built with the assumption the AC power
is a perfect/clean sine wave without an UPS present since
that would already be unrealistic. Even subcircuits within
the same gear will generate noise that must (/should/) be
rejected by the other subcircuits (one way or another).

Sadly, life isn't that way. And a lot of that audio gear is fine with
maybe 1% THD on the power line, but goes berserk with the poor waveform
that a typical UPS produces.

If the gear can't handle that, IMO it should just be
replaced or the flaws fixed. At that point if it is felt
there is still room for improvement, rather than a general
power conditioner look into something specific, "Balanced
Power". http://www.equitech.com/faq/faq.html

Well, the solution is not to put the audio gear on the UPS, but on the
direct power line. Since you don't need to keep the audio gear running
during an outage, that's fine. You put the computer on the UPS and then
all you have to worry about is the ground contamination and RF trash from
the computer grounds.
--scott

 

[kony]

That's another issue, I'm told that units that produce a "square"
waveform can actually damage components over time. Is this what all
the Best Buy/Circuit City type units produce? I assume there are
those that don't?

I can't tell you what Best Buy or Circuit City have.
See #4 on this page,
http://www.apc.com/solutions/display.cfm?id=0D72DB57-8963-47DA-9ADC4EB3FD07511D

Also, I'm told there are some where the Computer runs off the unit
constantly and some where the unit only comes "online" when needed.

Yes but be careful of your terms, since the type where the
computer runs off the unit constantly, meaning it's inverter
is always supplying the power to the (powered) equipment is
sometimes called an "online" UPS.

For example, the salesman at Cheap Guys where they currently have this
Ultra ULT31502 for $79.99

http://tinyurl.com/2r3e57

That looks like a good deal for $80. I don't know if it's a
good quality product or not, nor what your total load will
be so as to determine if the capacity is enough per powered
period.

and he says it's the type where it constantly supplies power to the
computer. What about APC units like this one?

http://tinyurl.com/35ncvg

Are you intent on buying one locally? Given the internet
you can really pick and choose exactly what you're getting.

Assuming what he told me is correct, are there any inherent benefits/
problems with whether the computer is constantly running off the
battery as opposed to an "online only when needed" configuration?
Again, wondering about damage to the computer.

The whole point is that your computer should be safe, or at
least in no more jeopary, using either type than not.
Remember they are intended to power a computer. Even so,
the computer would be more immune to AC mains problems when
the UPS is an online type or "running off the battery" as
you put it (which is a bit of a misconception as the UPS is
actually running the computer off the inverter which
receives power from a subsequent power stage that also
happens to (provide the power towards) charge the battery.

I like the readout on the APC case, but if one is superior at what
it's supposed to do, that's what I'd be most interested in. If the
battery is replaceable that would be great too. Even if you're only
saving 40% over the cost of a new unit, it's still 40%.

Generally the battery is a non-issue, pop it open (making
sure it's turned off first) and note the battery voltage,
capacity, size and terminals size. They tend to use common
battery sizes so you can buy a replacement online if it
isn't available locally.

 

[Mogens V.]

Sadly, life isn't that way. And a lot of that audio gear is fine with
maybe 1% THD on the power line, but goes berserk with the poor waveform
that a typical UPS produces.




Well, the solution is not to put the audio gear on the UPS, but on the
direct power line. Since you don't need to keep the audio gear running
during an outage, that's fine. You put the computer on the UPS and then
all you have to worry about is the ground contamination and RF trash from
the computer grounds.
--scott

Of cause. I was partly referring to the OP doing both audio and video on
those computers, so other gear might be hooked up - which it shouldn't.

Then again, I was also thinking of forces of nature et al.., as it was
suggested some UPS's may provide some added protection against such.
While I live in an appartment surrounded by reasonable large buildings
having measure against ligtning installed, nevertheless 'interesting'
currents can creep around. I'll do something else against that..

 

[kony]

Sadly, life isn't that way. And a lot of that audio gear is fine with
maybe 1% THD on the power line, but goes berserk with the poor waveform
that a typical UPS produces.

Yes but I'm saying, if it's important you can't just
randomly pick audio gear, this is one of many criteria in
discriminating what gear to use, and what existing gear
should be replaced or tweaked a bit in the power supply
subcircuit.

Well, the solution is not to put the audio gear on the UPS, but on the
direct power line. Since you don't need to keep the audio gear running
during an outage, that's fine.

You're right, "I" don't need it to run during an outtage,
but sometimes I feel I "want" at least a headamp and MP3
player running off batteries. However, some may really
"need" to keep running during an outtage. For example I
used to work as an engineer at a radiosStation and it was
certainly true then, but there were generators not $50
battery powered UPS. Another example would be a recording
studio, or a PA system at a department store to direct
customers... there are too many possible scenarios to really
see all possible situations when audio gear might need to be
working during an outtage, but I do feel a lower end
consumer UPS isn't usually the answer.

You put the computer on the UPS and then
all you have to worry about is the ground contamination and RF trash from
the computer grounds.
--scott

That's never a concern, the switching PSU used in a computer
have far more output noise than what little would remain
from an UPS with non-sine output, as is the noise created by
multiple high current circuits in a typical computer system.

 

[Richard Crowley]

"kony" wrote ...

You're right, "I" don't need it to run during an outtage,
but sometimes I feel I "want" at least a headamp and MP3
player running off batteries. However, some may really
"need" to keep running during an outtage. For example I
used to work as an engineer at a radiosStation and it was
certainly true then, but there were generators not $50
battery powered UPS.

The studio audio equipment is trivial compared to the power
it takes to keep the transmitter running, even at reduced output.

Another example would be a recording studio,

If I were a commercial recording (or video) studio reliant on
computer-based recording, I would keep at least the recording
computer on UPS (but not necessarily the audio equipment,
preamps, mixer, monitor amp/speakers, etc.) just enough to
save whatever recording was in process. If there is some
necessity to keep recording during power outages, that is
an entirely different scenario with different (and much more
expensive) possible solutions.

or a PA system at a department store to direct customers...

Life/Safety Systems, particularly for public buildings have
requirements for some kind of operability during power
interruptions. That was something designed into the
system by the architect and engineers, etc. The fire
alarms (audible & visible) and emergency lighting
(including EXIT signs) are usually the primary concern
to aid evacuation.

 

[William Sommerwerck]

Also, I'm told there are some where the computer runs off

the unit constantly and some where the unit only comes
"online" when needed.

I explained that in my previous posting. It's called a UPS -- an
uninterruptable power supply.

The device we commonly call a UPS is actually an SPS -- a standby power
supply.