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Need help choosing a UPS (plus general UPS tips)
Pentium100:
--- Quote from: APC link=http://nam-en.apc.com/app/answers/detail/a_id/1372 ---Plugging your UPS into a surge protector: In order for your UPS to get the best power available, you should plug your UPS directly into the wall receptacle. Plugging your UPS into a surge protector may cause the UPS to go to battery often when it normally should remain online. This is because other, more powerful equipment may draw necessary voltage away from the UPS which it requires to remain online.
--- End quote ---
This is if your surge protector is too weak or the other equipment connected to it is very powerful. Actually, it is advisable to connect a UPS to a decently sized surge protector - in the event of a big surge, the cheaper surge protector will blow up instead of the expensive UPS. I have installed a surge protector near the circuit breakers (the protector looks like a circuit breaker).
Freedom Kira:
It's probably best to only have the UPS connected to the surge protector, too. I think the APC quote there assumes you would plug other things into the surge protector.
chubbysumo:
--- Quote from: krumm on May 04, 2012, 10:44:15 PM ---The emulated sine-waves should not cause any problems. The psu in the computer turns it into a flat line anyway.
--- End quote ---
nope, AC to DC conversion usually results in a slightly bumpy wave, since no converter is 100% perfect. An AC power source converted to a DC output usually looks like this on an oscilloscope(there are 2 waves, there, 1 for unfiltered, and 1 filtered, most decent PSUs have a filter).
I would love a UPS for my system, but the UPS that I would need to power my system is way to expensive(my rig draws close to 900w from the wall under full stress use). I may get a UPS for my router and modem tho, because that would be pretty cheap.
nstgc:
Isn't there a way to rig up two PSUs? If you did that you could run two UPSs, one for each...which would still be pricey.
Pentium100:
--- Quote from: chubbysumo on June 03, 2012, 08:37:09 PM ---nope, AC to DC conversion usually results in a slightly bumpy wave, since no converter is 100% perfect. An AC power source converted to a DC output usually looks like this on an oscilloscope(there are 2 waves, there, 1 for unfiltered, and 1 filtered, most decent PSUs have a filter).
--- End quote ---
That is true for a unregulated power supply. A regulated supply has very small ripple.
Computers use switching power supplies that are more complicated than that.
First the 220V mains power is rectified to give 310VDC. Older power supplies just use a diode bridge, newer ones use a more complicated circuit to have a higher power factor. Then the DC gets chopped at high frequency and goes trough a transformer, then it is rectified again. A chip regulates the output voltage by controlling the duty cycle of the switching.
Computer PSUs have high frequency ripple but no 50/60Hz ripple. A computer power supply without PFC could be connected to 310VDC or a square wave for all it cares. PFC may act differently.
--- Quote from: nstgc on June 03, 2012, 10:26:27 PM ---Isn't there a way to rig up two PSUs? If you did that you could run two UPSs, one for each...which would still be pricey.
--- End quote ---
Two smaller UPSs would not be a lot cheaper than one big UPS. Also, while you can use multiple PSUs for a PC (powering different devices - one for all hard drives, another for everything else etc), the load would not be distributed between them - one would use more power. There are redundant PSUs that balance the load if they both work, but they are really expensive.
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