active PFC *REQUIRED* on PSUs to work on UPS's??

PSUs: The source of DC power for all components in the PC & often a big noise source.

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tjpark1111
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active PFC *REQUIRED* on PSUs to work on UPS's??

Post by tjpark1111 » Tue Mar 28, 2006 1:40 pm

I was wondering because the PSUs I'm looking at either have one or the other. The UPS I was going to buy is here: http://www.newegg.com/Product/Product.a ... 6842101002
My assumption is that without PFC is greatly increases the load on the UPS meaning shorter battery life, but I don't care as long as I get a minute or two to shut down, and if PFC isn't required, I was wondering if the UPS that I linked would be enough to power a 150w load at max for a few minutes.

lenny
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Post by lenny » Tue Mar 28, 2006 3:04 pm

Active PFC is not required. UPS run time will probably be decreased, but I've never tested to see by how much. But it'll still provide plenty of time for you to shut down your system. 750VA seems overkill for your needs though.

Devonavar
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Post by Devonavar » Tue Mar 28, 2006 3:57 pm

No, PFC is not required, but it will reduce the VA rating that you need, often by as much as 30-40% compared to a non-PFC version.

Look at it this way. With active PFC, the wattage rating of the UPS you linked to would effectively be the same as its VA rating (750W) as opposed to the much lower rating (450W) that applies to power supplies with passive or no PFC.

In any case, that UPS should be serious overkill for a 150W load.

Butcher
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Post by Butcher » Tue Mar 28, 2006 6:02 pm

Passive PFC should be of similar effectiveness to active. On the other hand I can't recall ever seeing a comp psu with passive PFC...

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Post by BillyBuerger » Tue Mar 28, 2006 6:46 pm

I just picked up a UPS for my workplace. I got 1500VA. But this is feeding 3 prescott P4 PCs, a monitor, 2 cisco routers, a 24port switch and and external hard drive. The PSUs in these PCs aren't anything special and are definitly not Active PFC. I'm only using about 50% of the UPS load. I hope this helps.

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Post by Elixer » Tue Mar 28, 2006 7:08 pm

Again, Active PFC is not required. I'm running my athlon XP system with a 9800pro and a 17" LCD monitor off a very cheap 575VA ups. This is with a non PFC power supply that's old and has poor effeciency. According to the utility that comes with it with my computer at full load including stressing the graphics processor, it says I'm using 55% of its capacity. It will run for ~7 minutes at full load, a little more than 10 at idle. So you shouldn't need that powerful of a ups. If you're only pulling 150W max then look for a ups in the 200 watt range.

merlin
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Post by merlin » Tue Mar 28, 2006 7:19 pm

Certainly active is not required. Even no pfc would work just fine.

Thing is, even passive PFC is only like 60-70% efficient vs 95-99% efficiency for active. If you care at all about how long your ups lasts, active is an awesome way to increase your battery time. (Thank this site for 80% efficient active pfc psus ^^)

tjpark1111
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Post by tjpark1111 » Tue Mar 28, 2006 9:44 pm

here's something in the 200watt range, would this be good? I'll only be hooking up the PC, not the monitor, speakers, anything like that because I haven't had any damage from that yet. I do want to be careful about internal PC components because I've heard PSUs or mobos have blown because of power outages. here's the link to it: http://www.newegg.com/Product/Product.a ... 6842101220

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Post by fastturtle » Wed Mar 29, 2006 6:58 am

I'd say go for an APC ES350 like what I'm using. Should give you between 5-8 minutes of run time with 17inch CRT hooked up. I'm using one on an XP1800 with Dual Burners that's on all the time. In my case, it's only providing between 3-5 minutes of run time but I'm also pushing loading of the unit due to aging CRT :oops:

stupid
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Post by stupid » Wed Mar 29, 2006 8:17 am

Butcher wrote:On the other hand I can't recall ever seeing a comp psu with passive PFC...
I believe in the UK and Europe in general, PSU are required to have active PFC, but it the US there is no such requirement.

Butcher
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Post by Butcher » Wed Mar 29, 2006 8:56 am

stupid wrote:I believe in the UK and Europe in general, PSU are required to have active PFC, but it the US there is no such requirement.
No, there is no such requirement in the UK or Europe.

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Post by jaganath » Wed Mar 29, 2006 9:31 am

I believe in the UK and Europe in general, PSU are required to have active PFC, but it the US there is no such requirement.

No, there is no such requirement in the UK or Europe.
Butcher, while technically correct, doesn't give the whole story: PFC is required in the EU for switched-mode power supplies with an output rating of 75W or higher, however the regulations do not specify that the PFC has to be active (ie passive PFC is acceptable).
A particularly important example is the millions of personal computers that typically incorporate switched-mode power supplies with rated output power ranging from 150W to 500W. Historically, these very low cost power supplies incorporated a simple full wave rectifier that conducted only when the mains instantaneous voltage exceeded the voltage on the input capacitors. This leads to very high ratios of peak to average input current, which also lead to a low distortion power factor and potentially serious phase and neutral loading concerns.

Regulatory agencies such as the EC have set harmonic limits as a method of improving power factor. Declining component cost has hastened acceptance and implementation of two different methods. Normally, this is done by either adding a series inductor (so-called passive PFC) or the addition of a boost converter that forces a sinusoidal input (so-called active PFC). For example, SMPS with passive PFC can achieve power factor of about 0.7...0.75, SMPS with active PFC -- up to 0.99, while SMPS without any power factor correction has power factor of about 0.55...0.65 only.

To comply with current EU standard EN61000-3-2 all switched-mode power supplies with output power more than 75W must include at least passive PFC.
wiki

Devonavar
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Post by Devonavar » Wed Mar 29, 2006 10:25 am

Yes, that Belkin should work fine for your system, even with a non-PFC power supply.

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Post by Oleg Artamonov » Thu Mar 30, 2006 2:28 pm

Moreover, some active PFCs (with full range input voltage only) may not work with some UPSes.

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Post by lenny » Thu Mar 30, 2006 4:36 pm

Oleg Artamonov wrote:Moreover, some active PFCs (with full range input voltage only) may not work with some UPSes.
Really? No experience here regarding that. All I can contribute is my Seasonic S12 (active PFC) works with my Belkin UPS.

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Post by Oleg Artamonov » Thu Mar 30, 2006 5:28 pm

Sure. For example, Delta Electronics GPS-400AA and GPS-450AA, Fortron FSP460-60PFN and FSP550-60PLN doesn't work with many UPSes with non-sinusoidal output (or even with sine output but without phase synchronization with input wave).

This is due to instantaneous overload at the moment of switching to batteries, when UPS output waveform rapidly changes.

Single range voltage (115V or 230V only) active PFCs are not affected at all.

With full range PSUs problem can be fixed by adjusting some of the time constants of active PFC scheme, so really it's not seems to be a huge problem for developers. Thus most of the newest PSUs are not affected: e.g., new Fortron series (FSPxxx-xxGLN/GLC, FSP GreenPS, Zalman ZM460-APS and so on) works well with any UPS.

Also this behavior depends on PSUs loading. E.g., in our tests (xbitlabs.com, article not published yet) Zippy HP2-6500PE works well with APC SmartUPS SC 620 with loading not more than 320W, but Zippy PSM-6600PE -- only with loading not more than 250W.

P.S. There's a discussion on this problem here, but it's in russian.
P.P.S. English language is not my strongest skill (native is russian), so I apologize if sometimes it can be hard to understand, feel free to ask.

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Post by sthayashi » Thu Mar 30, 2006 9:40 pm

merlin wrote:Thing is, even passive PFC is only like 60-70% efficient vs 95-99% efficiency for active. If you care at all about how long your ups lasts, active is an awesome way to increase your battery time. (Thank this site for 80% efficient active pfc psus ^^)
Just a friendly reminder that PFC != Efficiency. PFC affects Power Factor, i.e. the ratio of Watts to Volt-Amps. Efficiency is a ratio of PSU Output Power to Wall-Power.

jaganath
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Post by jaganath » Fri Mar 31, 2006 2:57 am

Oleg Artamonov

Wow! As in THE Oleg Artamonov, of Xbitlabs fame and the Research Institute of Physics, St Petersburg, Russia? Truly, we are not worthy! :oops:

I want to say thank you for all your excellent articles at Xbitlabs, some of them I consider even more informative than those here at SPCR. Keep up the good work!

Oleg Artamonov
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Post by Oleg Artamonov » Fri Mar 31, 2006 4:14 am

the Research Institute of Physics, St Petersburg, Russia?
Em... Moscow State University, Skobeltsyn Institute of Nuclear Physics, actually. I've never lived in St-Petersburg :)
I want to say thank you for all your excellent articles at Xbitlabs, some of them I consider even more informative than those here at SPCR. Keep up the good work!
Thanks!

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