Question

While I do have a surge protector to protect against overvoltage (hopefully), I have nothing against undervoltage. When a lightning storm hits, I had the lights flickering at some point. The PC continued to run, but it got me thinking of getting a UPS as a way to a) have a clean 120V/60Hz power source and b) have a way to shut down the PC in case something bad happens.

I heard not all UPS' protect against power spikes, so I wonder if someone has a recommendation? It does not need to keep the PC on for a long time if the power goes out, it's good enough if it shuts down the PC after 5 minutes or so.

There are 2 PCs connected. One is a Core i7-860 with a Radeon 5870 running Windows 7 Ultimate (so quite power hungry. It uses a 600W PSU but I have no measurements of the actual usage), the other one is a Windoes Home Server, running WHS/Windows Server 2003.

Any recommendations in the low-price segment?

Answer 1

One problem you may have in the low price versions is that they either have no software/pc link, or if they do - it is only for one computer.

What I recommend you do if you want to save money and be well protected is look on eBay for an office APC UPS, you can usually get £1000+ models for around £100 with no battery, then buy a replacement battery - usually between £30-£100.

If you want to save money and skip eBay, I would simply recommend you get two standard UPSs, Measure how long it takes you to turn them off. If it is under a minute, you can probably use a 700va UPS that should power the machine for at least 2 minutes at full load, but you usually get around 5-6 minutes.

FYI - Unless you get an expensive enterprise model cheap off of eBay or similar, it will be cheaper to get two new <1000va UPSs compared to one larger one when you look at price/power/features. And again, you may have a problem with just one when linking to multiple computers.)

Answer 2

I remember reading an article in a magazine, some years ago, which said a pretty good UPS could be made by having a car battery - maybe a truck battery - trickle charged continuously from the mains...

Then, at the same time, you run a 12VDC inverter to whatever your mains AC voltage is, from the battery.

If the mains power fails, your battery stops being trickle charged, but it resumes when the power comes back.

It's probably easier to protect a trickle charger from mains spikes, than a PC.

Given that your requirements seem a little higher than the average PC, some more heavy duty components may be necessary, a bigger battery, charger, inverter, etc, but it sounds doable.

Answer 3

UPS are generally divided in two major categories: "Offline" UPSes that power all equipment connected from main power supply when it's working and switch to batteries in couple of milliseconds on a power loss condition, and "Online", or "Double conversion" UPSes that always convert AC (120V in your case) to their internal battery voltage, and afterwise do the reverse job, so there are a) no gap immediately after power loss and b) it's output voltage has almost nothing to do with input voltage because of such complex conversion and filters on both ends and in middle. So you probably need the "online" one.

Also there is "Line-interactive" UPS': it is a variation of "offline" supplies with an intermediate converter between power line that handles excessive or insufficient voltage in line: e.g. if you have a 120V line and really there is only 105V such supply will convert it to roughly 120V again. AFAIK, these are unsuitable for spikes because of their limited range and time needed to switch between input voltages.

Answer 4

i'm living in the 'Wild West' of Ireland and I'm only too familiar with the problem :)

I swear by APC, their products are pure quality. My latest one is a APC Smart-UPS 750 INET (500W/750VA), price €200. This should easily get you over "flickering lights" or provide sufficient power to shut the system down properly.