Help me choose a UPS

[PAugustin]

Hello,

I really need to connect my computer to a UPS as the electric circuit in my house in unstable. I already had problems with one of my screens and I'd like to avoid that kind of problem.

The problem is : I don't know how to choose a UPS. I know it has something to do with the power of the equipement but that's all.

I have a 300W Enermax PSU in my tower,
my 19" Sony draws 135W
my 17" Eizo draws 80W.

How do I calculate the power of the UPS with this ?

Thanks for your help...

[Jammrock]

UPS systems actually rarely use Watts (W) to rate their power capabilities. They use something similar called Volt-Amperes (VA - Apparent Power). See the following link from APC for the explanation:

http://sturgeon.apcc.com/whitepapers.nsf/docID/742DD811A2C5CBC785256A5C007A142F/$FILE/WhitePaper15.pdf

As explained in the document, the VA rating is less than W rating. They say anywhere from 0.55 to 0.75, but the most common single answer I have seen is 0.63.

In your case, 300 W (which is the maximum power consumption, but more than likely not the actual power drawn) + 135 W + 80 W = ~515 W max.

Convert to VA: 515 W / 0.63 = ~817 VA

Basically you will want a 900 VA - 1000 VA UPS to handle the full load for any decent amount of time. Or a 500 VA to 650 VA UPS IF it is PFC.

That would put you in the market for one of these:

http://www.apcc.com/products/back-ups_pro/index.cfm#specs

Jammrock

[PAugustin]

Thanks a lot for your explaination. I'm going to look at that link.

Oh and you talked about PFC ? What is it ?

[LvR]

Good advice there from Jammrock - From personal experience, just about any APC or Meissner unit that can hold that load for the period of time you require would do.

[PAugustin]

I also forgot to said that the main use of this UPS would be to filter the power before it gets to my hardware. Does that mean I can choose a smaller UPS ?

[Greebe]

nope... a true UPS powers whatever device from a power supply/charger (AC>DC) which maintains the batteries. Then the batteries power an inverter (DC>AC) which supplies whatever device with go juice.

If you exceed the inverters power capability then it would work about as good as a grossly underrated pc supply.

[PAugustin]

OK thanks.
Now I need to find the money to get me a 1000VA UPS. Those things don't come cheap at all :-(

[az]

You need an "online" UPS, if you want to properly filter your current.

AZ

[Greebe]

PFC=Private First Class

Not! hehe... really it's stands for Power Correction Factor and that's a tad more than what is neccessary to get into for your purposes. Actually think he was refering to a SPS type UPS where it's not driving the load at all times. These cost and weigh less than True UPS's but do not react fast enough in many cases to prove viable for mission critical applications.

Check http://www.kalglo.com/standby.htm

[SteveC]

I've got an APC Smart-UPS (1400VA) which does me great.

I altered a 4 way power strip to plug into it so I can plug normal plugs into it too. I run all this off it:

My PC (Athlon 1900+ normal otherstuff - a few drives etc)
21" old Dell (Nokia) Monitor
Shuttle SV24 Mini PC
Motorola Cable Modem
Netgear Cable Router
8 Port Hub
Netgear Wireless Access Point

Currently at 8% load (Not got first 2 items on - goes to about 10-15% when I have). Which is a runtime of 2 hours

[Greebe]

Also another note... APC (the company) which produces UPS's believes that SPS's are true UPS's dispite the fact that they do make both types... don't buy into the BS. If it switches from line to battery power it's not a true UPS.

Tho I'm not saying they are per se bad

[PAugustin]

Wow thanks for all those info. I'm gonna look around to see what I can find. I know I can get APC, Belkin, MGE, Nitram, and a few others. I'll see what's available. I'd like to get a cheap one but if I have I'll put more money because my system is pretty expensive and I don't want to lose it...

[az]

Remember, for the best filtering, neither an offline, nor a line-interactive UPS is good. The expensive online type only

AZ

[Brian R.]

Where I work, we all have Belkin 650 VA "Regulator Pro" units. They seem to be quite reliable.

I have had mixed results with the long-term reliability of APC 650 VA units.

I think 650 VA units have more than adequate capacity for your set up.

[DGhost]

another thing is that his computer probably draws under 200W (possibly under 150W, all things considered) as he only has a Duron 900, a G400MAX, a recent model HD, and all the other assorted goodies. as long as he is not overclocking that is.

i would have to say that he could probably get by with a 700VA. if he ever upgraded the system a lot he might have some problems with both monitors connected, but it is doable...