UPS Question

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HMSDOC

Other than powering your computer for a few minutes in the event of a power
loos and thus letting you save your work and shut down normally, what is the
benefit of aun UPS as opposed to a surge protector.

I notice that the UPS are graded in terms of wattage and how long they will
keep your computer running after a loss of power. Does the wattage of the UPS
have to match that of your power supply. How do you determine what you would
need..is it the same as you would choose for the PSU and if you got a bigger
power supply then you needed is it OK to pair it with an UPS that is less in
wattage than your PSU but probably enough to run your system?

Howard
 
Depends on what you get. If you get one that has a AV suffix, it will not
just protect your computer from surges, it will also maintain a constant
line voltage within set limits, including "brownouts" vs. only working when
the power fails completely. They can also save autosave your work, even if
you are not present when a power failure occurs.

You don't have to match your UPS to your power supply. The higher wattage
UPS you get, the longer it will provide power to your computer. Keep in mind
it is providing 110-120 V to your power supply, your power supply is
stepping down the voltages going to the computer.

I bought one from CyberPower, mostly because I had questions when I bought
mine, and when I called them, I actually got to talk to a real person who
took the time to talk to me. I've been very satisfied with it, and the
software that comes with it is great...displays alot of info like Input and
Output voltages, battery state and load, backup time available, etc.

Good Luck,
Fitz
 
UPS and power strip protector are both rated in joules.
They use equivalent circuit to provide same protection.
Protection from surges that typically do not exist AND
ineffective protection from surges that damage electronics.

To obtain protection from that destructive type of surge,
then the protector must connect an AC main less than 10 feet
to central earth ground. That is what a surge protectors does
during the surge - shunt. Earth ground - not the protector -
is protection. A protector is only effective when it connects
to protection. And since that plug-in protector (power strip
or UPS) does not even claim to protect from the destructive
type of surge, then manufacturer avoids all mention of
earthing.

A surge protector is only as effective as its earth ground.
Earthing is the most critical 'system' component. That makes
ineffective protectors so easy to identify. No mention of
critical earthing AND no dedicated wire to nearby earth ground
is how one identifies an ineffective protector.

Therein lies the missing facts they would rather not
discuss. Effective surge protector is called 'whole house'.
So effective and so inexpensive that the telco typically
installs a 'whole house' protector on your phone line - for
free. 'Whole house' protector for AC electric is priced on
the order of tens of times less per protected appliance,
compared to plug-in protectors. And provides more joules.

To sell their ineffective protectors, manufacturers simply
forget to mention any of this. They forget to describe what a
surge protector does. If they mentioned earthing, then you
might ask some embarrassing questions. Go ahead. Where is the
most critical component of a surge protection 'system'? Where
is that central earth ground connection?

Additional information including examples of effective
protectors is discussed in the newsgroup
alt.certification.a-plus on 7 Jul 2003 as "Opinions on Surge
Protectors?" which can be read at
http://tinyurl.com/l3m9 .

That plug-in UPS only provides data protection from
blackouts and brownouts. Different from building wide UPSes
that also may provide transient protection - because building
wide UPSes have an essential earth ground connection. A surge
protector is only as effective as its earth ground.
 
HMSDOC said:
Other than powering your computer for a few minutes in the event of a power
loos and thus letting you save your work and shut down normally, what is the
benefit of aun UPS as opposed to a surge protector.

I notice that the UPS are graded in terms of wattage and how long they will
keep your computer running after a loss of power. Does the wattage of the UPS
have to match that of your power supply. How do you determine what you would
need..is it the same as you would choose for the PSU and if you got a bigger
power supply then you needed is it OK to pair it with an UPS that is less in
wattage than your PSU but probably enough to run your system?

Howard
Click to expand...

a surge protector is simply nothing more than an MOV (metal oxide varistor)

it normally has a high resistance, but as voltage rises above it's rating...
it's resistance decreases..
it thus has the ability to eliminate minor voltage surges...
but will burn out entirely with a very large surge...

a UPS (uninterruptible power supply) contains a battery powered inverter...
so will not only continue to give power in case of a voltage disruption...
it also offers superior surge protection capabilities.

UPS's are generally rated in Volt-Amps (VA)
because power factor is taken into account VA does not exactly equal power
(or watt's) *however* as a general rule of thumb you might as well figure
that a 300VA UPS (for example) would be good for about 0.6 X 300
or 180 watts.

take into account periphery devices such as printers and your monitor...
to be safe, you should total up the total power all your equipment draws
then purchase the next size larger UPS


i selected an inexpensive 585VA unit to backup and amd-1200 with a printer,
scanner and TFT display...
that was over a year ago and it has worked without the slightest problem...

since it runs slightly warm, i put it on 3/8" standoffs to keep it from dire
ct contact with the floor
 
philo's answer is good if surges were differential type -
transients between two wires - typically exist only as noise.
Therefore MOVs would never enter conducting state because
noise voltage does not exceed 330 volts. But those type of
surges typically don't exist. Destructive surges are a type
that must be earthed. Destructive type of surge cannot be
eliminated by simply shorting two wires - as philo suggests.

Earth ground is the protection - not some MOV inside a
plug-in protector. A surge protector (those MOVs) are only as
effective as its earth ground. Earth ground is the most
critical component in a surge protection 'system'. The
protector is simply one 'system' component that is useless
without earthing.

That plug-in UPS has no earth ground. It avoids all mention
of the most critical 'system' component - earthing. Plug-in
protectors not connected to the most critical 'system'
component offer superior protection only from a type of surge
that does not typically exist. Sufficient to claim surge
protection - as long as they avoid mentioning earth ground.
But all this was explained in that other newsgroup - complete
with examples of effective protectors.
 
w_tom said:
philo's answer is good if surges were differential type -
transients between two wires - typically exist only as noise.
Therefore MOVs would never enter conducting state because
noise voltage does not exceed 330 volts. But those type of
surges typically don't exist. Destructive surges are a type
that must be earthed. Destructive type of surge cannot be
eliminated by simply shorting two wires - as philo suggests.

Earth ground is the protection - not some MOV inside a
plug-in protector. A surge protector (those MOVs) are only as
effective as its earth ground. Earth ground is the most
critical component in a surge protection 'system'. The
protector is simply one 'system' component that is useless
without earthing.

That plug-in UPS has no earth ground. It avoids all mention
of the most critical 'system' component - earthing. Plug-in
protectors not connected to the most critical 'system'
component offer superior protection only from a type of surge
that does not typically exist. Sufficient to claim surge
protection - as long as they avoid mentioning earth ground.
But all this was explained in that other newsgroup - complete
with examples of effective protectors.
Click to expand...

yes i should definately have mentioned grounding

it's especially important on a UPS or surge suppressor if you want
protction!

ideally the UPS would be grounded...then all equupment grounded
via the UPS...
 
UPS has grounding - safety grounding. That is not earth
grounding. Previous requirement posted repeatedly- a short
connection - less than 10 feet. Requirement traceable to an
engineering concept called wire impedance and other
engineering concepts such as single point earthing and induced
transients.

First on the list of reasons is wire impedance. Assume a
UPS is plugged into a 20 amp receptacle that is 50 feet from
breaker box. Safety ground wire measures less than 0.2 ohms
resistance. But it is also maybe 130 ohms impedance to the
surge. A 100 amp surge shunted by that UPS or plug-in
protector would leave protector AND adjacent computer at
something less than 13,000 volts. 13,000 volts difference
between protector and breaker box due to too much wire
impedance. Too much impedance because the earth ground
connection is much greater than 10 feet.

'Whole house' protector connected less than 10 foot would
have maybe 40 ohms impedance on that 6 AWG bare copper ground
wire. 400 volts between breaker box (and rest of building)
and earth ground. Voltage so low that internal protection
inside all appliances is not overwhelmed - no surge damage.
The less than 13,000 volts may seek other and destructive
paths to earth via appliances because surge protector circuit
is too far from earth. One classic symptom of this less than
13,000 volt transient would be modem's 'No Dialtone Detected'
error message.

Demonstrated is why protectors adjacent to a computer are
not earthed and why that means no effective protection. Other
factors, such as induced surges (because ground wire is
bundled with other wires) is not discussed here. But induced
transients also are why plug-in protectors are not effective -
being not properly earthed.

Again, the plug-in manufacturer instead avoids all mention
of earthing. Why? That 13,000 volt example is just another
reason why he must avoid mentioning earth to sell his
ineffective, overpriced, typically undersized protector. Yes,
those adjectives are accurate. Just look on his box. He even
fails to mention the difference between safety ground and
earth ground because he does not claim that kind of
protection. A surge protector is only as effective as its
earth ground - which is why the less expensive, larger joule,
well earthed 'whole house' protector is the effective
solution.

Again, I am only repeating what was discussed in that
previous newsgroup at
http://tinyurl.com/l3m9

Then the art of earthing. Surge protectors are simple
science. What makes protection effective and what is the
artform is earthing - discussed by engineers on 28 Jul 2002 in
two threads in the newsgroup misc.rural:
http://tinyurl.com/ghgv and http://tinyurl.com/ghgm
 
Lots of good & correct info posted.

Yes, surge protectors are bit of an interesting marketing idea.
o Whole house surge protection exists
---- it's used in industry, often DIN rail mounted, big & a bit expensive
---- vastly more capable than the few MOV, GDT & such in a plug
o Telco surge protection is throughout the system
---- the consumer kind don't protect from lightning unless its remote
---- real lightning strikes require very big telco lightning protection
---- again vastly more capable than the products pushed (and pricey)

Lightning striking your phone "local-loop" is only going to be stopped
by the modem being unplugged, and even then it can shoot along the wall,
into a power socket and blow everything that way. Colleague in Texas had
exactly that happen in their offices - hit the tree, tree to phone-line, ran
along a water pipe near where the telco cable entered, into the mains,
and promptly wrote it's version of Picasso all over a lot of data disks.

So focus on the UPS re brownout + surge + power-loss-shutdown.

If this is commercial, APC are good, but Compaq are better.
UPS have a higher failure rate, Compaq more rugged & pricey.

Don't treat an UPS like a low-wattage modem re location:
o They can get warm in operation
o They are a *very* high energy store
o Failures are not always contained

The very big UPS can shower the surroundings with sparks,
admittedly a rare failure - just realise it's batteries of stored KVA.
So don't clog airholes or stick behind curtains in office/domestic.
Worth having a small desk light run off it too... *smile*

Globally I suspect blackouts may increase, as the actual mapping
of the powergrid doesn't extend to understanding it's physics fully.
It's the most sophisticated thing ever built - and the network level
difference of paper overground v underground is significant in that
harmonics can occur during switching themselves causing problems.
Powergrids are now managed (incredibly) by semiconductor switches,
to squeeze more out of a power-line or network of them than before.
That is managing-tighter something-not-fully-understood.

Which is even before one considers the general near overload status
of UK, Europe, USA and Canada. The grid protects from a single point
failure - the problem is containment depends on spare capacity.

So UPS whilst a "not needed in my backyard" may be something
increasingly considered - if data on that machine is important.
 
Dan (http://www.dansdata.com) suggests putting together your own
true UPS (the common ones, so called, are really "backup PSes" and
are no better than a power strip except in power failures) from
a battery charger, a big lead+acid (maybe gel) battery, and a good
quality power inverter. He discusses one such UPS, with pictures.
(Of course, this doesn't help much with lightning.)
 
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