Can anyone give me some guidelines on buying a ups, like how much va do I need, how long of a time limit, does a ups act like a power surge protector, how do I determine what I need?
Most UPS devices filter out spikes and regulate the voltage to a predetermined level too; in most cases, all you will want the thing to do is keep your machine supplied with power for long enough to shut itself down normally, in the case of home and desktop machines, this need only be a few minutes, in the case of servers, a little more breathing space is sometimes required to make sure that databases are disconnected safely, disk mirroring is at a suitable stopping place and so on.
What sort of computer setup are we talking about?
How many VA (kinda like watts, but not exactly) you need depends on your system. A good rule of thumb is to match the specs of your power supply. So, if you have a 300-watt PS in your computer, get a 300 VA UPS. Most computers don’t use the full rating of the PS, even under full load, but better safe than sorry. You’ll want to allow extra for your monitor, too, so figure another 50 VA for that. Get the power rating off each peripheral you want to power and add that to the total.
How much time? Well, go the the max you can afford. The more the merrier. Really, at minimum you’ll need enough time to close out your programs, save your work and do a proper shutdown. Say, 5 minutes, minimum. But more can’t hurt.
Most UPS units have surge protection built in, however, since the MOVs that actually provide the protecton fail after absorbing their rated surge energy, you’ll still want a regulr surge supressor plugged in too, since they are cheaper to replace than the UPS.