VanguardLH wrote:
mike wrote:

certs.lbl.gov/pdf/55718.pdf

"if the power is out for more than a few seconds, it's likely
to be out longer than even the best ups can handle."

So perhaps I understood your statement incorrectly. Rather than
denounce the abilities of a UPS for backup power, it seems you are
saying that either the outage will be a few seconds or it will last for
hours (and longer than a "best" UPS can cover the outage). Okay, but
that apparently is regional since outages in my area are either
momentary (perhaps less than a second) or they are for many minutes up
to maybe an hour. Rarely do we get outages that last more than a couple
hours or are days long (and in that case a huge area has been hit). In
those cases, we're more concerned about barring unneccessary visits to
the fridge so we don't lose our refridgerated foods.

You can certainly purchase a UPS that can last for many hours to cover
just your system case and the monitor (and nothing else, like powered
speakers, printers, scanners, and other peripherals). Some folks even
get gas-powered generators to have power that covers an outage lasting
for several days (depends on the fuel supply). For a home user, yeah,
they might only go for a UPS that lasts them a couple hours versus a
hospital that needs a far longer lasting setup but then only few outages
would outlast that UPS but the home user can still get a "best" UPS that
lasts for many hours. Best always equates to price and there was no
restriction on price in your or the OP's posts, so "best" goes as high
as the technology allows - and that's a long time.

Typically consumers buy very underpowered UPS. That's because they
never bother to compute how long the UPS will keep their system up along
with not willing to pay the price for that long uptime. They go cheap,
just like they do with PSUs when they build their own. Getting an 18kVA
unit would let you continue using your computer for probably around 10
hours. Some users, however, are looking to use a UPS just for data
integrity by letting the OS gracefully shutdown. A UPS for that task
only needs to keep the computer powered for a few minutes during an
outage. If your area gets hit with stuttering outages (it's out, comes
back, goes out again, goes out, back on, and repeats) then you probably
want a UPS that will work over several stutters (so your host doesn't
bounce after the UPS has been drained).

"out longer than even the best ups can handle". That all depends on
just what backup power setup you have. The "best" could be an extremely
huge backup power system and even include a gas-powered generator and a
huge fuel tank. When you said "best", you left open-ended your argument
because "best" is dictated by the users needs and their wallet.

From the article you gave, "From a customer¢s perspective, electricity
reliability problems come in a variety of forms. Interruptions or
outages during which voltage drops to near zero for periods of time
ranging from a few seconds to several hours are the most visible
problems and affect the widest range of electricity-consuming
equipment." Okay, but who says the "best" UPS setup can't survive a
multi-hour power outage? Even if you toss out the backup gas-powered
generator scenario, you can still get a large UPS or get those that can
be ganged together to give you 2, 5, 10 hours, or more, of backup power.
Because consumers are focused on price, they shouldn't be looking at
hours of backup power (so your argument that a power outage is a few
seconds to over hours long is irrelevant). They should be looking at
one that gives them time to close their documents and let the OS
shutdown gracefully. That size unit is within the range of their
personal finances.

Unless the user has a lot of cash (often far exceeding the cost of their
personal consumer-grade computer), they should be concerned about data
integrity rather than uptime when looking to add a UPS in their setup.
You buy more uptime and its expensive. It's cheaper to get just enough
uptime to preserve data integrity. Home users don't have the needs of
hospitals, banks, or commercial datacenters where the "best" UPS for
those needs are far beyond the financial means of end users; however,
the "best" backup power systems can keep you up for days, weeks, or
indefinitely (if you have a setup that lets you stay off the "grid").

You're getting far too hung up on the word "best". Delete that word
and concentrate on the fact that on page 39 of the referenced article,
the scatter graph demonstrates that the VAST majority of power outages
are less than 1000 cycles. Of course, there are outages that are
longer than that and still shorter than your backyard nuclear reactor
can support.

The OP claims that the computer is attended. Based on that, he should
start shutting things down as soon as the outage manifests and all will
be well.
Yes, there will be instances where the power comes back on before
the ups would have run down, but those instances are statistically
insignificant. For home users, making the UPS run time 2 or 5 or 10x as
long
improves the situation little...at great expense.

I have not stated the obvious: the run time must be at least as long
as it takes to recognize the outage plus the shutdown time.

Bottom line is...IFF the computer is attended, he doesn't need a wire
or shutdown application. If he mis-stated the "attended" scenario,
he needs to restate it, if he expects relevant input.