The Technofile Web site has moved.

Technofile is now located at
Please update your links, bookmarks and Favorites.  

Why you need an uninterruptible power supply

technofile  by al fasoldt

Columns and commentaries in a life-long dance with technology

Simple gray rule

Why you need an uninterruptible power supply

By Al Fasoldt

Copyright © 1994, The Syracuse Newspapers

When a storm ripped through our area a few weeks ago, it knocked out the electric power over a few square miles. I rushed home from work to help clean up the damage and found my house dark—except for my computer monitor, which was still glowing brightly.

The computer and its disk drives were still humming away, too. They were attached to a $100 device that supplies power for a limited time if the house wiring goes dead.

Such devices are called uninterruptible power supplies. If you do important work on your computer, they could save your bacon—and your files.

A properly designed UPS once cost many hundreds or even thousands of dollars. But the burgeoning PC market has prodded manufacturers to bring out cheaper models. Because they use newer circuitry, these inexpensive uninterruptible power supplies are often just as good as the megabuck models of a few years ago.

The basic idea behind a UPS is simple. It's usually a small box that sits beside your computer or on the floor. You plug a UPS into the wall outlet and plug your computer and peripherals into the UPS. If the 120-volt line goes out, the UPS takes over.

They do this through battery power. Inside a UPS is a heavy-duty battery that is always kept charged as long as you're getting electric power to your house. If the house wiring drops below a certain voltage, the UPS switches itself to battery power.

A device that turns the battery's direct current to alternating current (the kind you have in your home) is also part of any UPS.

Many uninterruptible power supplies also clean up the electricity that comes from the house wiring, filtering out sudden voltage surges, called spikes, and doing a few other things to keep the electrons from misbehaving.

In general, a big and expensive UPS will run your computer longer on battery power than a small and cheap one. But even the $100 models will power a typical PC for a half hour or longer, depending on how many peripherals you have plugged into the UPS.

(A tip: Your monitor and a laser printer, if you have one, use more power than everything else combined, so you'll get longer standby power from a UPS if you leave them plugged into the standard outlet.)

If you're thinking that a half hour of standby power isn't very long, keep in mind that most power interruptions last only a few seconds—and most of those are brownouts, in which the voltage drops, instead of out-and-out power failures. During a sustained blackout, you'd have time to save your work and shut down your computer properly.

I must add a personal note. In one of those odd coincidences that are too bizarre to predict, the power in my neighborhood went out while I was writing the last paragraph of this column. Unfortunately, I was working on my secondary computer—the one that is not plugged into my UPS—and the sudden shutdown wrecked the file I was working on, and I had to rewrite this piece.

I have vowed to add another UPS.

 Image courtesy of Adobe Systems Inc.technofile: [Articles] [Home page] [Comments:]