Can you tell me if I have the right UPS?

[Anonymous user]

Do I have the right size UPS? The selector on the website isn’t helpful! I don’t really know how to fill in all the specifications.

I have an APC model # BE550G, 550VA/330 Watts, 8 outlets. Plugged into the battery side I have my 17 inch CRT monitor, tower, and Linksys wireless router. Plugged into the surge side I have my desk lamp, computer speakers, and Comcast telephone plug.

I don’t know much about my computer and how much power it uses but here’s some info that might be helpful: “System information” says my processor is x86 Family 15 Model 4 Stepping 1 GenuineIntel ~3066 Mhz. I have 2 GB of total virtual memory. The system information shows me: Cisnet, Intel®, Celeron ®, CPU 3.06 GHZ.


The power supply in my tower is 400 watts. Does that count too?

I haven’t had any problems with my UPS, but I want to make sure I’m using it right and that I have the right size.

Thanks for any advice or explanations that might help me understand this better.

[Anonymous user]

Hi,

Thanks for your reply.

Can you tell me, by the processor I listed in my first post, what choice on the APC processor selector do I choose? That's where I'm very confused because that choice isn't listed, unless it is called something else and I just don't recognize it. My computer is 4 years old--shouldn't the processor I have be listed though??

The only thing listed that I can see on the power cord to the tower says 300 v, 3 x 0.824 mm2 (18 AWG). (Not sure what any of that means).

I have had this UPS for a few months now and haven't had any problems with it whatsoever. Occasionally it will let me know there was electrical noise and it will say that it is on AC power again, indicating it went to battery backup. My input voltage says 124 volts on the APC info.

Does any of that help?

[BillP]

Hi Vicky,

The wattage and Amp draw is what you will actually need to calculate if the UPS is the right size or not. There are 2 values to check, the Watts and Volt Amps (VA). Most power supplies will and equipment will have this info listed on it near where the power cord goes into it, i.e. where you saw 400W on the computer. The first thing to do would be to add up all the Watt requirements. The second thing to do would be add up all the Amps drawn then multiply by the voltage (120 in North America) to get the total VA. Now that you have your total Watts and VA for the equipment you want to connect to the UPS we can determine what size UPS you will need. For now lets just look at the Watts for the computer since that's the only info we have and ignore all the other equipment.

You have a 400W power supply in the computer and the UPS has only 330W output when on battery, right off the bat I would say your UPS is to small. If you take into account a general rule of only loading your UPS to 80% of its capacity then you are 136W over where you should be (330 * .80 = 264, 400 - 264 = 136). The 80% rule is to allow for inrush current your load may draw during boot up or during heavy utilization. As you can see we are significantly over the UPS ability and we haven't added the rest of the equipment in yet.

Now I'm not saying to run out and buy a new UPS just yet. Just because the power supply says its rated for 400W doesn't mean it will always draw that much. If you want to be 100% safe and not risk the UPS going into overload and dropping the load (cutting its output power) then I would highly recommend a larger UPS, but if you don't mind risking it going into overload when you have a power outage then you can keep it on the UPS you have for now and see how it works. If the equipment isn't drawing more power then what the UPS can handle when the power goes out then the UPS will keep everything up fine, but as soon as the draw increases above the threshold the load will be dropped.

If you do decide to size up a new UPS then just add up the Watts and Amp draw and then put those values into the selector and it should give you a few options. If you still are not sure about what its suggesting then post your Watts and Amps here and I'll take a look at it.

[BillP]

hmm the power cable information is just for the cable. you'd want to check the power supply itself on the computer where the cable plugs in. if you have had the UPS for a while and havent experienced any problems with overloads with daily use, you should be fine. but on a UPS this size, i definitely wouldnt add anymore equipment to the battery back up outlets.

[Anonymous user · Accepted solution]

My computer came with a 300 watt power supply and I had it replaced with a 400 watt several months ago, and yes haven't had any problems. I have since decided to plug the monitor into a separate power strip, just to lighten the load from what I have plugged into the UPS. Not sure if that makes sense. I guess it does lighten the load a little, right? But my friend pointed out that in the case of an actual blackout, the APC would keep my computer running but I wouldn't have power to my monitor! Makes sense. My main use of having the UPS is for quality and care of protecting my computer should anything happen. As long as I get that, that's all I care about. I don't need battery backup for extended use, just don't want my computer to get messed up by anything.

Anyway, I wish I knew more about all this stuff. The guy at the store told me this UPS unit was all I would need, and I do believe him. I've learned that the total system doesn't even use what it's capable of using but only uses what it needs, so just because I have a 400 watt power supply in my computer doesn't mean that it actually draws that much at a time. Thus, I'm sure that's why what I have is working out fine. I'm not overloading my system.

And yes, I don't plan on adding any more to it. But in the future if and when I get a faster system or anything, I'll go ahead and get a higher UPS too.

Thanks for the replies, I appreciate it.

Vicky