I understand that I have to add up the power need of all the
components. How do I go about it?
I can find the voltage need for the (1)monitor (Dell's 19 in LCD ),
(2)keyboard, and (3)mouse, but do I have to open the case and check
individual components or can I figure out if I have the info from
packing slip? How to? Also, I want to add another 256 MB of memory
down the road.
Here is my system's components - from packing slip):
Dell Dimension 8100 Series, Pentium 4, Processor 1.3GHz
256MB RDRAM
32MB NVIDIA GeForce2 MX 4X AGO Graphics card with TV-Out
40GB Ultra ATA Hard drive (7200RPM ) + another one I added (80MB)
3.5 In Floppy Drive
Integrated 3Com Etherlink, 10/100 PCI Ethernet Controller
48X Max variable CD-Rom Drive, Factory Install
SB Live! Digital Sound Card with 1024 voices
Altec Lansing ACS-340 Speakerswith Subwoofer
8x/4x/32x/ CD-RW Drive, 2nd bay
Should I get the list from Device Managers instead?
Thanks.
PS. This was long overdue; I had 2 unexpected deaths of nephew and
niece - under age 25 - in my family (one in last year summer and then
one in last year fall and messed up my plan of doing that last summer.
I shouldn't wait any longer as this area (of past2 years) has more
black out than everywhere I have ever lived.
>I understand that I have to add up the power need of all the
>components. How do I go about it?
>I can find the voltage need for the (1)monitor (Dell's 19 in LCD ),
>(2)keyboard, and (3)mouse, but do I have to open the case and check
>individual components or can I figure out if I have the info from
>packing slip? How to? Also, I want to add another 256 MB of memory
>down the road.
As a rule of thumb, just use the power that the power supply is designed
for. ESpecially modern LCD monitors, the power drain is smalll.
For your computer, it should be on a label on the back of the computer. By
law, the max power drain of an article MUST be placed on a label visible to
the consumer.
Your memory is irrelevant. If your memory taxes your power supply you will
have worse problems than your UPS.
>Here is my system's components - from packing slip):
>Dell Dimension 8100 Series, Pentium 4, Processor 1.3GHz
>256MB RDRAM
>32MB NVIDIA GeForce2 MX 4X AGO Graphics card with TV-Out
>40GB Ultra ATA Hard drive (7200RPM ) + another one I added (80MB)
>3.5 In Floppy Drive
>Integrated 3Com Etherlink, 10/100 PCI Ethernet Controller
>48X Max variable CD-Rom Drive, Factory Install
>SB Live! Digital Sound Card with 1024 voices
>Altec Lansing ACS-340 Speakerswith Subwoofer
>8x/4x/32x/ CD-RW Drive, 2nd bay
Irrelevant. the power of your power supply is all you need.
>Should I get the list from Device Managers instead?
No. Just look at the label on the back of the computer.
(If it is not there, then look for the power supply rating -- 200Watts,
500Watts,....)
In article <1129323718.369541.109100@g43g2000cwa.googlegroups .com>,
amanda <amanda772005@yahoo.com> wrote:
:I understand that I have to add up the power need of all the
:components. How do I go about it?
:I can find the voltage need for the (1)monitor (Dell's 19 in LCD ),
:(2)keyboard, and (3)mouse, but do I have to open the case and check
:individual components or can I figure out if I have the info from
:packing slip?
The keyboard and mouse are trivial. The monitor and the computer power
supply will both have stickers on them that indicate the voltage and
the amperage... for example, the device next to me indicates
that it accepts 100 VAC at 13A. The -maximum- power consumed by
the device is the product of the voltage and the amperage -- 1300 VA
in this particular case. The -maximum- is seldom hit (there is
usually a safety factor), and the maximum for any device is -usually-
at startup ("the inrush current")... though for a fan or other
electric motor, the maximum occurs when motor is being accelerated
[the timing of which depends on the motor design.]
UPS's are rated either in VA (Volt-Amps), or in W (Watts). The
conversion between VA and W is not entirely straight forward.
For standard equipment there is a factor of .707 (square root of 2)
in there, but computer equipment approaches closer to .9 or 1.
You -could- go through and do some messier calculations based upon
the individual components and the power supply efficiency specification,
but it is a lot easier to size for as near the maximum as you can
afford.
A typical off-the-shelf consumer UPS should be able to handle a
typical home computer and LCD monitor, but the more souped-up the
computer, the more likely that you'd need a more expensive UPS.
There is a a lot more to know about UPS's than just the power rating,
though. Different UPSes convert power in different ways and there
can be major differences in the kind of power problems that they
protect you against.
You might want to go through the UPS Selector on the websites
of Powerware or APC.
--
Many food scientists have reported chocolate to be the single most
craved food. -- Northwestern University, 2001
> UPS's are rated either in VA (Volt-Amps), or in W (Watts).
> The conversion between VA and W is not entirely straight forward.
Thanks for that info. I was told that Watt = Volt * Amps.
> For standard equipment there is a factor of .707 (square root of 2)
> in there, but computer equipment approaches closer to .9 or 1.
>
>
> You -could- go through and do some messier calculations based upon
> the individual components and the power supply efficiency specification,
> but it is a lot easier to size for as near the maximum as you can
> afford.
I'd prefer the easier way. It's just a hoem system.
>
> A typical off-the-shelf consumer UPS should be able to handle a
> typical home computer and LCD monitor, but the more souped-up the
> computer, the more likely that you'd need a more expensive UPS.
>
>
> There is a a lot more to know about UPS's than just the power rating,
> though. Different UPSes convert power in different ways and there
> can be major differences in the kind of power problems that they
> protect you against.
Are you referreing to inline and standby?
The problems here has been blackout and then come back right away.
>
> You might want to go through the UPS Selector on the websites
> of Powerware or APC.
> --
> Many food scientists have reported chocolate to be the single most
> craved food. -- Northwestern University, 2001
"amanda" <amanda772005@yahoo.com> writes:
> Walter Roberson wrote:
> [..]
>
> > UPS's are rated either in VA (Volt-Amps), or in W (Watts).
> > The conversion between VA and W is not entirely straight forward.
>
> Thanks for that info. I was told that Watt = Volt * Amps.
Assuming a unity power factor, that is the case. However, computers
don't always present a purely resistive load.
So, you size by volt-amperes which takes this into account, and you
oversize the UPS with more VA than claimed Watts.
To get any more precise, you'd need some electrical engineering
courses and get to learn some really funky math involving imaginary
numbers and phasors and the like.
<...>
> UPS's are rated either in VA (Volt-Amps), or in W (Watts). The
> conversion between VA and W is not entirely straight forward.
> For standard equipment there is a factor of .707 (square root of 2)
> in there, but computer equipment approaches closer to .9 or 1.
The sqrt(2) factor is already included in the AC rating (it is efficient
voltage, not peak). With modern switching power supplies the reactive
factor is so small that you don't have to worry about it. It is important
only in big motors and transformers.
<...>
> There is a a lot more to know about UPS's than just the power rating,
> though.
The basic numbers are
(1) Maximum power rating. Not everything needs power, e.g. printers and many
other peripherals can be restarted easily when power returns.
(2) How long the power needs to be delivered. A good estimate is the time to
shut down the systems gracefully.
For a home user the other things aren't worth the price. E.g. if the house
is in a storm-prone zone, its electric power already has protection against
flash surges etc. (It does, doesn't it...)
In article <diq9dc$jmf$1@nyytiset.pp.htv.fi>,
Lassi =?ISO-8859-15?Q?Hippel=E4inen?= <lahippel.at.ieee.org@moon.invalid> wrote:
>Walter Roberson wrote:
:> There is a a lot more to know about UPS's than just the power rating,
:> though.
:The basic numbers are
:(1) Maximum power rating.
:(2) How long the power needs to be delivered.
:For a home user the other things aren't worth the price. E.g. if the house
:is in a storm-prone zone, its electric power already has protection against
:flash surges etc. (It does, doesn't it...)
We're in a "storm-prone zone", but those storms tend to be of
the frozen water variety.
The power around here is not down particularily often. Sometimes
wind or snow will knock out hydro lines (more-so as you get away
from the main city), but it isn't an every-month occurance.
Power outages around here are statistically more likely in the early
summer. The transformer fires tend to be in the summer (perhaps lightening
triggered). More of an issue is the suicidal rodents.
Therefore around here, when a power problem does occur, there is
a good chance that it will be accompanied by a brownout. Standard
consumer UPSs are -not- suitable for brownout protection. No
"standby" UPS is: you need at least an "inline" (single inversion)
one for that, and better yet a "true online" (double inversion).
Consumer "standby" UPSs have to actively switch on the battery
backup. There is a delay while they do that. If your equipment
is a modern PC, then it -probably- has enough capacitors in it
to ride over the temporary power loss, but if you have a device
which does not have a big power supply and which is not acting
in a role in which a momentary loss of power is acceptable, then
at least an "inline" should be purchased.
After having done a bunch of UPS research for work, if I were
trying to protect sensitive / expensive equipment at home,
I would go "true online" (double inversion) despite the noticably
higher cost. For lesser equipment, I wouldn't consider less than
an "inline" (single inversion) -- not if the equipment had the
potential to be damaged by brownouts. Around here (which is
*not* Big Thunderstorm Country... usually), I've never seen
any device fried by a power surge, but I have had a few devices
fried by brownouts.
--
"No one has the right to destroy another person's belief by
demanding empirical evidence." -- Ann Landers
>"amanda" <amanda772005@yahoo.com> writes:
>> Walter Roberson wrote:
>> [..]
>>
>> > UPS's are rated either in VA (Volt-Amps), or in W (Watts).
>> > The conversion between VA and W is not entirely straight forward.
>>
>> Thanks for that info. I was told that Watt = Volt * Amps.
Watts is volt*Amp averaged over time. If volts are sometimes positive and
sometimes negative when Amps are positive, the averge will cancel out and
watts will be much less than max Volts times max amps. Computers should be
pretty resistive (both volts and amps are positive and negative at the same
times) except maybe on power supply startup.
>Assuming a unity power factor, that is the case. However, computers
>don't always present a purely resistive load.
>So, you size by volt-amperes which takes this into account, and you
>oversize the UPS with more VA than claimed Watts.
>To get any more precise, you'd need some electrical engineering
>courses and get to learn some really funky math involving imaginary
>numbers and phasors and the like.
In article <1129349041.672026.96240@f14g2000cwb.googlegroups. com>,
amanda <amanda772005@yahoo.com> wrote:
>Walter Roberson wrote:
:> There is a a lot more to know about UPS's than just the power rating,
:> though. Different UPSes convert power in different ways and there
:> can be major differences in the kind of power problems that they
:> protect you against.
:Are you referreing to inline and standby?
standby, inline, true online, single inversion, double inversion...
:The problems here has been blackout and then come back right away.
In instances where the power is prone to going out for very short times,
the power seen on the line is seldom just a simple "full power until
suddenly there isn't, and then suddenly later there is full power again."
Very short power problems are often accompanied by very weird
transients and voltage and current combinations, and those are a
*lot* more dangerous to equipment than just doing the equivilent
of yanking the plug.
When you get power problems, is it always just "bye-bye lights"?
Or do the lights flicker? And especially, do the lights dim?
The more the lights tend to flicker and dim, the more you need
a single-inverting or (better yet) double-inverting UPS.
--
"It is important to remember that when it comes to law, computers
never make copies, only human beings make copies. Computers are given
commands, not permission. Only people can be given permission."
-- Brad Templeton
Unruh <unruh-spam@physics.ubc.ca> writes:
> comphelp@toddh.net (Todd H.) writes:
> >"amanda" <amanda772005@yahoo.com> writes:
> >> Walter Roberson wrote:
> >> [..]
> >>
> >> > UPS's are rated either in VA (Volt-Amps), or in W (Watts).
> >> > The conversion between VA and W is not entirely straight forward.
> >>
> >> Thanks for that info. I was told that Watt = Volt * Amps.
>
> Watts is volt*Amp averaged over time.
For what it's worth, this really isn't mathematically accurate.
The original poster can ignore this though, as we're out on a tech
geek tangent. :-)
> If volts are sometimes positive and sometimes negative when Amps are
> positive, the averge will cancel out and watts will be much less
> than max Volts times max amps.
That's one way to look at it.
Perhaps a more accurate model to think of is in terms of phase. AC
voltage and currents are sinusoidal (non-geeks: that just means they
look like a sine wave going positve, and negative, one cycle every
1/60 of a second here in the US where we have 60Hz power).
Now, if you're turning on a lightbulb (which is electrically pure
resistive), and you had a scope on voltage and current, those
waveforms would be 100% in phase. This means a "unity power factor"
and your 60W light bulb is going to require only 60VA of generator
output to do it's thing.
Now if voltage and current waveforms are NOT in-phase (as happens when
the load--in this case a computer with a very non-linear switching
power supply--is not purely resisitve, but is slightly inductive or
slightly capacitive in nature) you have to make a distinction between
Watts and VA because your "250W computer power supply" might demand as
much as, say 350VA out of the wall. How much it demands depends on
its design. Switching power supplies are electrically far more yucky
than a simple resistive little lightbulb.
In this case where voltage and current waveforms are not in phase
because of a "reactive" load, the power source has to "work" harder
(the "electrical effort" is measured in Volt-Amperes) than the actual
real power (measured in Watts) that ends up doing useful work.
As an aside, this is why electrical distribution systems go to great
lengths to balance the "power factor" and make it as close to 1.
Electric power lines are inductive in nature (as are motor loads for
all those HVAC blower motors in our homes), so peridically, up on your
electric poles you'll see square gray thingees that are capacitor
banks designed to balance out the power factor to cancel out some of
that inductance out there plugged into the electric grid. The power
company's generators need to handle the load in Volt-Amperes, but they
can only charge customers for real energy use (measured in
Watt-hours).
Circling back to the present discussion of UPS's, like any other power
source, the capacity of it is best reflected in Volt-Amperes. APC
being a geeky engineering company accurately portrays that.
All the consumer needs to know is that they're going to need more VA
of UPS than they have a total of Watts in use on their computer. It's
best to trust APC's sizing program though.
The math is pretty wacky. Your choices are either a) dealing in
time-domain differential equations, or b) frequency-domain fun with
algebra that uses complex numbers with real and imaginary parts using
phasor notation. These are the tools to _really_ explain what's going
on in AC circuits. It's the stuff of 2nd year electrical engineering
study.
Walter Roberson wrote:
> In article <diq9dc$jmf$1@nyytiset.pp.htv.fi>,
> Lassi =?ISO-8859-15?Q?Hippel=E4inen?= <lahippel.at.ieee.org@moon.invalid> wrote:
>
>>Walter Roberson wrote:
{snip}
> potential to be damaged by brownouts. Around here (which is
> *not* Big Thunderstorm Country... usually), I've never seen
> any device fried by a power surge, but I have had a few devices
> fried by brownouts.
I'm likely in the same city as nrc.gc.ca, and while I have not
seen a "device fried by a power surge", I have had a surge
protector burned out by lightning down a telephone line. The
attached "device" was not damaged. (Tripp-Lite honored their
warranty and replaced the surge protector.)
Reasonably sophisticated surge protectors (not the $19.95 ones on
the wall at the local big-box store) also tend to filter incoming
so that the "weirdness" associated with transient failures
doesn't get through. Of course, they do not provide UPS capability.
On 10/15/2005 10:58 AM, Todd H. wrote:
> Unruh <unruh-spam@physics.ubc.ca> writes:
>
>>comphelp@toddh.net (Todd H.) writes:
>>
>>>"amanda" <amanda772005@yahoo.com> writes:
>>>
>>>>Walter Roberson wrote:
>>>> [..]
>>>>
>>>>
>>>>>UPS's are rated either in VA (Volt-Amps), or in W (Watts).
>>>>>The conversion between VA and W is not entirely straight forward.
>>>>
>>>>Thanks for that info. I was told that Watt = Volt * Amps.
>>
>>Watts is volt*Amp averaged over time.
>
>
> For what it's worth, this really isn't mathematically accurate.
>
> The original poster can ignore this though, as we're out on a tech
> geek tangent. :-)
>
>
>>If volts are sometimes positive and sometimes negative when Amps are
>>positive, the averge will cancel out and watts will be much less
>>than max Volts times max amps.
>
>
> That's one way to look at it.
>
> Perhaps a more accurate model to think of is in terms of phase. AC
> voltage and currents are sinusoidal (non-geeks: that just means they
> look like a sine wave going positve, and negative, one cycle every
> 1/60 of a second here in the US where we have 60Hz power).
>
> Now, if you're turning on a lightbulb (which is electrically pure
> resistive), and you had a scope on voltage and current, those
> waveforms would be 100% in phase. This means a "unity power factor"
> and your 60W light bulb is going to require only 60VA of generator
> output to do it's thing.
>
> Now if voltage and current waveforms are NOT in-phase (as happens when
> the load--in this case a computer with a very non-linear switching
> power supply--is not purely resisitve, but is slightly inductive or
> slightly capacitive in nature) you have to make a distinction between
> Watts and VA because your "250W computer power supply" might demand as
> much as, say 350VA out of the wall. How much it demands depends on
> its design. Switching power supplies are electrically far more yucky
> than a simple resistive little lightbulb.
>
> In this case where voltage and current waveforms are not in phase
> because of a "reactive" load, the power source has to "work" harder
> (the "electrical effort" is measured in Volt-Amperes) than the actual
> real power (measured in Watts) that ends up doing useful work.
>
> As an aside, this is why electrical distribution systems go to great
> lengths to balance the "power factor" and make it as close to 1.
> Electric power lines are inductive in nature (as are motor loads for
> all those HVAC blower motors in our homes), so peridically, up on your
> electric poles you'll see square gray thingees that are capacitor
> banks designed to balance out the power factor to cancel out some of
> that inductance out there plugged into the electric grid. The power
> company's generators need to handle the load in Volt-Amperes, but they
> can only charge customers for real energy use (measured in
> Watt-hours).
>
> Circling back to the present discussion of UPS's, like any other power
> source, the capacity of it is best reflected in Volt-Amperes. APC
> being a geeky engineering company accurately portrays that.
Yeah, but doesn't this all just talk about the amount of current the UPS
can deliver? Another key component should be: How long? For batteries,
that is usually measured in Amp-Hours. I suppose that it could also be
"VAh"
My experience with batteries is mostly related to storage capacity for
the "house" batteries of my trailer. For practical purposes, you can
use Amp=W/V to calculate loads. For AC I use rated wattage/120 and add
5% for the inverter. It comes out about right. (The harder part for my
situation is figuring out the time function for things that are high
load but short interval, like pumps and blowers.)
>
> All the consumer needs to know is that they're going to need more VA
> of UPS than they have a total of Watts in use on their computer. It's
> best to trust APC's sizing program though.
Which does take into account "time". But they don't tell you that part
of what you need is just a bigger "gas tank"
>
> Another take on the Watts vs VA is here:
> http://www.marvac.com/fun/power.aspx
>
> The math is pretty wacky. Your choices are either a) dealing in
> time-domain differential equations, or b) frequency-domain fun with
> algebra that uses complex numbers with real and imaginary parts using
> phasor notation. These are the tools to _really_ explain what's going
> on in AC circuits. It's the stuff of 2nd year electrical engineering
> study.
>
> Best Regards,
Fortunately, the author of that page says that "for most purposes, and I
will let you define most, VA and Watts can be thought of as the same."
In article <84mzlay85p.fsf@ripco.com>, Todd H. <comphelp@toddh.net> wrote:
:Circling back to the present discussion of UPS's, like any other power
:source, the capacity of it is best reflected in Volt-Amperes. APC
:being a geeky engineering company accurately portrays that.
When I was sizing UPSes about 2 years ago, APC's online calculator had
bugs in it -- there were places it accepted an input in VA,
applied a load factor of .707, then said the result was VA, and
sized accordingly. I'm likely misremembering the exact details, but
the effect was to drive you to a bigger UPS than you had asked for.
--
Many food scientists have reported chocolate to be the single most
craved food. -- Northwestern University, 2001
Please help with buying a UPS for my system 
Linear Mode
