UPS : Computer Hardware Buyers’ Glossary


UPS (Uninterruptible Power Supply). A UPS is a box containing a battery that goes between your computer and the AC (Alternating Current) wall outlet. If the power fails, it keeps your computer going for 10 minutes on battery backup power. Most power outages are less than 3 seconds long. Ten minutes gives you time to shut down the software gracefully, saving all your work in the event of a long outage. A surge protector will protect your computer for spiking overvoltages, but can do nothing for sags, when the power disappears or the voltage dips. For that, you need a UPS to kick in during the low voltage period. In some rural areas or in old buildings, your computer will keep rebooting on your unexpectedly when the power flickers. You have no choice but to get a UPS.

Make sure you get a UPS big enough to power all your equipment, except perhaps the printer. When you hook it up, make sure you don’t plug in more devices than it can handle. UPS ’s are rated in VA (Volt-Amps) which is roughly the same thing as watts. If you want to understand the difference, read this essay.

It never hurts to buy an overrated power supply — it just covers you over longer outages and produces smoother power during the outages. Of course, larger rated UPSes (Uninterruptible Power Supplies) will cost more. You can save on your UPS by getting a power smart computer and LCD (Liquid Crystal Display) instead of CRT (Cathode Ray Tube) screen which uses less power. You might power your big power-hungry laser printer off the UPS but put a small ink jet on it.

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