The IT Nerd

Have you ever been typing away on your computer when the power suddenly goes out sending everything you’ve been working on to oblivion? If you’ve been the victim of something like that, then you might want to consider getting a uninterruptible power supply (UPS) for your computer. A UPS will not only keep your computer alive long enough for you to safely save your files and shut down your system (many of them have software that will automatically do that for you), but they will often help protect your equipment from power surges and power drops.

There are two types of UPS devices available:

• An off-line UPS remains idle until a power failure occurs, and then switches from utility power to its own power source, almost instantaneously.

• An on-line UPS continuously powers the protected load from its energy reserves stored in a lead-acid battery or flywheel, while simultaneously replenishing the reserves from the AC power. It also provides protection against all common power problems, and for this reason it is also known as a power conditioner and a line conditioner.

I usually recommend a on-line UPS as it will protect you from more power problems than an off-line UPS. So you want to look for a UPS that does “power conditioning” or “Automatic Voltage Regulation.” Also look for software that shuts down your computer in the event of a blackout. As mentioned earlier, many UPS products have software that do this along with a cable that connects to your computer’s USB or serial port so that the UPS can send the shutdown signal. This way your computer is protected even when you are not at home or close to the computer when the power goes out.

Finally, there’s the size of UPS that you need. UPS devices come in sizes that will power a single computer (500 VA being the least that I would go with for a single computer) to something that will run a data center (usually running into the megawatts). Most companies who make UPS devices have configurators that will allow you to enter all of your equipment and it will make the decision for you in terms of the size that you need. But here’s how I usually make the call of how big of an UPS I need. The only things that you need to protect with a UPS is the computer and a LCD monitor (never plug a CRT monitor into a UPS because the power draw is too high). You don’t need to plug in your printer or your speakers as it will drain the battery faster. Given the power draw of the average PC with an LCD monitor, you typically need somewhere between a 500VA and 1000VA UPS. By going with a larger UPS (something closer to the 1000VA end of the scale or more), you get more runtime (the time the UPS will run computer will before it runs out of power) which can be handy if live in an are that has frequent blackouts.

Finally, once you purchase your UPS you should make a note of the date you purchase it so that you can either replace it with a new one or replace the battery. Batteries typically last 2 to 3 years depending on the model, and it is sometimes cheaper to replace the entire UPS rather than replace the battery. By keeping an eye on this, you can make sure that you’re always protected.

UPDATE: I’ve posted a more detailed version of this article here based on a question from a reader.

This entry was posted on July 24, 2008 at 10:17 am and is filed under Tips with tags Uninterruptible Power Supplies. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.