UPS Questions

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

Moderators: NeilBlanchard, Ralf Hutter, sthayashi, Lawrence Lee, Devonavar

Post Reply
TomMe
Posts: 138
Joined: Mon Mar 20, 2006 6:23 am
Location: Antwerp, Belgium

UPS Questions

Post by TomMe » Fri Apr 20, 2007 12:17 pm

Since I'm having problems with my PC sometimes automatically coming out of standby (link) and since I've had my share of power outages, I'm currently thinking about buying a UPS. Still not decided though, I don't really feel comfortable about these devices "protecting" my PC.

I've noticed that UPS prices are quite high, for example €200 for a APC Back-UPS RS (BR800I). This unit is rated at 540W, I would expect much more for that amount of money.

Then I read this..
Lower UPS costs: Lower current draw also means that smaller capacity Uninterruptible Power Supply (UPS) units can be used. As UPS units are priced in direct proportion to their current capacity (VA), a PF of 0.98 versus one of 0.6 can traslate into a 40% reduction in purchase cost. Again, in an enterprise setting with hundreds or thousands of PCs, the savings can be very significant.
..at the Power Supply Fundamentals.

I have a SeaSonic S12-430 and perhaps will replace it with a Seasonic S12 Energy+ 550. Both have a Power Factor of around 1. If I understand everything correctly, does this mean that a UPS with VA of 600 would be suficient?

Also important, can I connect the UPS to a power strip? Last time I tripped a breaker by flipping the switch of a lamp while I was working on the PC.. I wouldn't want that to happen again, so I'd like to connect the lamp (and TV, VCR, 360W TV speakers, etc) sepparate from the UPS, so the UPS can protect the PC from the lamp (and other devices).

Thanks for reading. :D
[size=75][color=#1f2676]AM2 4000+ with XP-90 and Nexus 92mm | MSI K9N SLI Platinum | Corsair 2x1GB DDR2 PC6400 | MSI GF 7900GS Passive + Nexus 92mm | SBLive! Value | suspended WD 2500KS | Seasonic S12-500 | BenQ1620 | Plextor PX-W4012TA | Lite-On LH-20A1S | 2 Nexus case fans[/color][/size]

CA_Steve
Moderator
Posts: 7394
Joined: Thu Oct 06, 2005 4:36 am
Location: Monterey Bay, CA

Post by CA_Steve » Fri Apr 20, 2007 1:12 pm

That's a pricey UPS.

My XS900 was $120 on sale.

Do you need that much VA capacity? Probably not...my e4300 @ 2.5Ghz, 2GB RAM, 8800GTS, 37GB Raptor, 320GB Caviar, DVD writer, 22" LCD, router, cable modem, and old Palm V draw 140W web surfing and 190W while gaming.

So, I have 34min of battery power when not gaming....way more than enough time to shut stuff down in an orderly manner.

Plugging the UPS into a power strip- not recommended if the power strip has any surge-protection built in. Your UPS is designed to monitor the AC line for drops, overvoltage and noisy lines. A surge supressor on the power strip will alter the AC enough to where the UPS may not respond in a timely manner.

EsaT
Posts: 472
Joined: Sun Aug 13, 2006 1:53 am
Location: 61.6° N, 29.5° E - Finland

Re: UPS Questions

Post by EsaT » Sat Apr 21, 2007 12:13 am

TomMe wrote: Then I read this..
Lower UPS costs: Lower current draw also means that smaller capacity Uninterruptible Power Supply (UPS) units can be used. As UPS units are priced in direct proportion to their current capacity (VA), a PF of 0.98 versus one of 0.6 can traslate into a 40% reduction in purchase cost.

I have a SeaSonic S12-430 and perhaps will replace it with a Seasonic S12 Energy+ 550. Both have a Power Factor of around 1. If I understand everything correctly, does this mean that a UPS with VA of 600 would be suficient?
Wrong, UPS has to be always capable to pumping out necessary amount of real power/watts which isn't same thing as volt-ampere in AC.
Power factor just tells how much higher apparent power consumption is than real power consumption. (if PF is 0.5 and device consumes, say, 100W then apparent power would be 200VA)
You need to take VAs into account only if your PC's PF is bad, in other cases only watts matter.


And to be precise you need to remember that PSU always draws more power than it outputs, 550W PSU under full load can well draw near 700W from wall. But considering nearly all PCs stay under 300W max consumption losses in PSU stay well under 100W.
"The power of accurate observation is commonly called cynicism by those who have not got it."
-George Bernard Shaw

TomMe
Posts: 138
Joined: Mon Mar 20, 2006 6:23 am
Location: Antwerp, Belgium

Post by TomMe » Sat Apr 21, 2007 12:29 am

EsaT, I don't quite follow you. Both PSUs I quote have a Power Factor of 1. So if one of them consumes 400W, then, to my understanding, apparant power should be 400VA.

How is it then that what I say is wrong? Please elaborate.. :D
[size=75][color=#1f2676]AM2 4000+ with XP-90 and Nexus 92mm | MSI K9N SLI Platinum | Corsair 2x1GB DDR2 PC6400 | MSI GF 7900GS Passive + Nexus 92mm | SBLive! Value | suspended WD 2500KS | Seasonic S12-500 | BenQ1620 | Plextor PX-W4012TA | Lite-On LH-20A1S | 2 Nexus case fans[/color][/size]

EsaT
Posts: 472
Joined: Sun Aug 13, 2006 1:53 am
Location: 61.6° N, 29.5° E - Finland

Post by EsaT » Sat Apr 21, 2007 4:27 am

While "same size" VA is entirely different than W, apparent power also includes reactive power which is electricity just circling back and fort between power source and appliance and something which isn't consumed.
(except higher transfer losses caused by higher current)

Most UPSes are made "for power factor of ~0.6" meaning their real output capability is VA-rating multiplied by 0.6 if it isn't told separately.
In power consuming devices power factor of 1 just tells that it doesn't draw reactive power in addition to real consumed power but you can never use that unused VA-output as substitute for watts.



http://en.wikipedia.org/wiki/Electric_power
http://en.wikipedia.org/wiki/Power_factor
http://www.apcmedia.com/salestools/SADE ... _R0_EN.pdf


TomMe wrote:I've noticed that UPS prices are quite high, for example €200 for a APC Back-UPS RS (BR800I).
So you had to select the most expensive available shop?
http://geizhals.at/eu/a81448.html
"The power of accurate observation is commonly called cynicism by those who have not got it."
-George Bernard Shaw

TomMe
Posts: 138
Joined: Mon Mar 20, 2006 6:23 am
Location: Antwerp, Belgium

Post by TomMe » Sat Apr 21, 2007 6:00 am

So you're saying the Power Supply Fundamentals guide is wrong then?

Pff, this is becoming way too technical for me.. I just want to protect my PC. :cry:
[size=75][color=#1f2676]AM2 4000+ with XP-90 and Nexus 92mm | MSI K9N SLI Platinum | Corsair 2x1GB DDR2 PC6400 | MSI GF 7900GS Passive + Nexus 92mm | SBLive! Value | suspended WD 2500KS | Seasonic S12-500 | BenQ1620 | Plextor PX-W4012TA | Lite-On LH-20A1S | 2 Nexus case fans[/color][/size]

EsaT
Posts: 472
Joined: Sun Aug 13, 2006 1:53 am
Location: 61.6° N, 29.5° E - Finland

Post by EsaT » Sat Apr 21, 2007 6:23 am

For that part it's wrong.
It would be right only in case UPSes could output as much real power as apparent power but I haven't yet heard of single such UPS.

So just forget VA-ratings totally and look always only watts.



Now do you want UPS to accept normal power cords?
"The power of accurate observation is commonly called cynicism by those who have not got it."
-George Bernard Shaw

TomMe
Posts: 138
Joined: Mon Mar 20, 2006 6:23 am
Location: Antwerp, Belgium

Post by TomMe » Sat Apr 21, 2007 6:50 am

Normal power cords would be the idea, I think. :?

I don't really speak German, so it wouldn't be a good idea to buy from a German shop. The lowest price I can find for the one I quoted is around €180.

As I understand it, you have to swap the batteries every few years, right? What about the device itself, do I have to swap it after a while?
[size=75][color=#1f2676]AM2 4000+ with XP-90 and Nexus 92mm | MSI K9N SLI Platinum | Corsair 2x1GB DDR2 PC6400 | MSI GF 7900GS Passive + Nexus 92mm | SBLive! Value | suspended WD 2500KS | Seasonic S12-500 | BenQ1620 | Plextor PX-W4012TA | Lite-On LH-20A1S | 2 Nexus case fans[/color][/size]

J. Sparrow
Posts: 414
Joined: Wed Jan 17, 2007 7:55 am
Location: EU

Post by J. Sparrow » Sat Apr 21, 2007 7:15 am

Xbit labs has some interesting PSU reviews where they connect the PSU to an UPS and see how much load they can put on it before it screams for overload.

In this one you can see a SmartUPS 620 connected to several units. The limit is between 315-380W, so it's 0.6 or less!

The power factor of your PSU might be even different from the one published in reviews. E.g. my S12 exhibits a power factor of 0.87-0.92.

May I suggest you to buy a power meter? it will help you in assessing your real power requirements and power factor.

EsaT
Posts: 472
Joined: Sun Aug 13, 2006 1:53 am
Location: 61.6° N, 29.5° E - Finland

Post by EsaT » Sat Apr 21, 2007 1:26 pm

TomMe wrote:I don't really speak German, so it wouldn't be a good idea to buy from a German shop.
Neither do I...
And just half week ago I ordered Canon HV20 HDV camcorder from Austrian shop.

From shops in that list I have experiencies from Compuland, Computeruniverse.net and Alternate. (maybe also e-bug) Especially Computeruniverse is as good shop as it can get.
Others have good experiences with Mindfactory.


Back-UPS ES has lot of versions with various sockets, also there seems to be versions of Back-UPS RS (line-interactive and better voltage regulation) with French sockets.
http://www.apc.com/products/category.cf ... yCode=benl

Also MGE has few versions with normal sockets.
http://www.mgeups.com/intl/solution/small.htm


Lifespan of battery depends from use, couple years is kept as somekind worst case minimum in many places but if you don't mind decrease in battery operation time nearly half dozen years would be possible.

At least some consumer priced power meters are very inaccurate when there's reactive power present and professional meters tend to be in price class "if you need to ask you can't afford".
"The power of accurate observation is commonly called cynicism by those who have not got it."
-George Bernard Shaw

Post Reply