Just picked up a UPS for dirt cheap, but ......

Fact 1: for a UPS "the volt-amps rating is approximately 60% higher than the actual wattage"
Fact 2: That UPS is rated at 450 Volt Amps, so that means the output is 270 Watts.
Fact 3: From experience a vanilla AMD 64 + Nvidia 6800 uses in excess of 310 Watts.

Conclusion: If you take facts one two and three as true then the conclusion is inevitable. That particular UPS should not be plugged into a modern gaming rig.

Disclaimer: I don't know wtf i'm talking about.
 
it might suffice for a single PC (with no perpherals or monitor) if the PSU has Power Factor Correction and the outage doesnt occur when your pegging the rig. Your likely "typical' VDC draw is around 100>200 Watts, then the temperature and the PSUs efficiency come into play and its VAC draw could be anywhere from 200>400 Watts, and the KVA youd need could be much higher if the PSU doesnt have Power Factor Correction as UPSs really dont like nonlinear loads when they are on batteries.


Id recommend using it for a perpheral or monitor instead of your main box
 
Id recommend using it for a perpheral or monitor instead of your main box
Click to expand...

A UPS for your printer; for all those times when you really really have to print something and the power goes out. "Of course i bought UPS's for our printers sir, this is a MISSION CRITICAL laser printer!"
 
personally I was thinking of my KVMs
but mission critical laser printers would do :p
 
OK, I thought it might be a bit anemic for a gaming rig. What if I got another one just for my rig? They had 4 more on the rack today. BTW, Czar how about an FAQ on what to look for in UPS's for us uninitiated folks.
 
well I like FAQs\Tutorials to be fairly comprehensive
and there are still a few areas that require more study in my mind
but this is sort of a partial
orignal question was how much to power XYZ components

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

see I have no real idea of the average or worse case draw of the
24port Linksys switch, time warner cable modem, and linksys accesspoint

the definative answer would be to measure that with a watt meter
they are rather cheap and had at most hardware stores
a far fancier one is reviewed here
http://www.systemcooling.com/watts_up_pro-01.html

as far as what the PSU would actually pull thats dependent on both the load on it
(what its doing) and its efficiency at that load and temperature (Id guess it to be less that 100 watts on average and worsecase at 130W VDC
then factoring in AC Conversion and efficiency

well a supply @ 62% efficiency with a 65W VDC works out to about 105W VAC
a good guess for "typical"
a supply a 69% effeciency at 150W would draw 217W VAC not a bad worse case
(supplies have an effciency sweet spot I grabbed both of those from an FSP350 Mike Chin reviewed)

one of the other things to bear in mind is Power Factor Correction
Batteries dont like nonlinear loads


cut and paste
--------------------------------------------------------------------------------------------------------------



Power Supply System Integration Part 2: Battery Backup @ Power Electronics Technology

UPS Nonlinear Loads

Most end users are oblivious to the problems encountered when an online UPS interacts with nonlinear load, such as a switchmode power supply. Fig. 3, on page 42, illustrates the interface between an online UPS and a switchmode power supply. The switchmode supply within the host system consumes its current in high amplitude pulses, and as a result overloads the UPS, distorts its output and degrades in performance. This isn't the case if the SMPS has power factor correction (PFC); and in the United States most SMPS don't have PFC.

Repeated measurements under practical conditions show that in non-PFC SMPS, the current peak to rms ratio reaches a crest factor in the range of 2.5 to 3.5. This high crest factor imposes a difficult load for the UPS.

Manufacturers specify UPS capacity in volt-amperes, and set the UPS current limit with resistive loading. This affects the user in two ways: first, the actual power (in watts) that the online UPS can deliver is 75% to 80% of its VA rating. Second, the UPS cannot support a nonlinear load like a SMPS to full power capacity. In fact, it can support an SMPS only rated to 30% to 40% of its capacity. A 1kVA online UPS will only be suitable for backing up a system energized by a 300W to 400W (non-PFC) switchmode power supply. Attempts to draw higher power by the SMPS will severely distort the output of the UPS and may result in shutdown. Some UPSs support nonlinear loads to various degrees, but the above rule is safe to use as a guideline.

The whole idea of generating a high-purity sinewave within the UPS, and then rectifying it within the SMPS is wasteful. A UPS may be deployed to run non-electronic loads, such as lights or motors. However, this is a minor portion of the market for online UPS. Many applications back up computers and telecom devices, as well as instrumentation systems used for critical applications. In all of these applications, the immediate load for the UPS is the SMPS within the systems. Peak current and inrush current are associated with this load at startup. This current of 40A to 80A per SMPS will cause the UPS to shutdown due to overloading, or the UPS must transfer the load to utility to draw its inrush.
Click to expand...

Im "upgrading" the importance of active PFC in purchasing, as it does seem to have a great deal to do with not abusing and effectively employing the capacity of an online UPS (and by extention Id assume a line interactive UPS \ SPS when its on batteries, a far more common UPS scheme)


a bit more on PFC
PFC Decoded
and on UPSs
Power Conditioning 101
DIY UPS all @ dansdata ;)

--------------------------------------------------------------------------------------------------------------------------------

Id vote for research,
1 get a watt meter and measure the worse case for all the equipment involved
2. see if the supply is PFC or not
3. select a UPS based on that ;) (adding additional capacity for a nonlinar load)


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

so either you employ a UPS manufacturers calculator based on an unknown baseline they set for a "typical" config + assorted components, you go for overcapacity or you measure
 
category_five said:
A UPS for your printer; for all those times when you really really have to print something and the power goes out. "Of course i bought UPS's for our printers sir, this is a MISSION CRITICAL laser printer!"
Click to expand...

Don't put your laser printer on a UPS. At least that's what the warnings on UPS units from APC say.
 
it was a joke but yes thats correct,
they are very power hungry nonlinear loads from what I gather ;)
 
Hmm... No sine or AVR.. only 450VA.... Too bad I missed this deal. $13.50 is a cheaper price than what the 12V 7Ah replacement batteries usually sell for. I could've bought a bunch and robbed the batteries out of them. :D
 
You must log in or register to reply here.
Back
Top