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Do You Need A UPS?

By: Jonathan Z. Kremer

It could happen to you at any time, and in a blink of an eye. All it takes is a small spike, surge, brownout, or any other fluctuation in the voltage , and your equipment can be permanently damaged, your data destroyed, and your operating system files corrupted. Faulty electrical power can insidiously wear down your system over a period of time, without you knowing - until - eventually, it fails. One way of avoiding such disaster is to install a UPS. A UPS (Uninterrupted Power Supply) is a power supply that includes a battery to maintain power in the event of a power outage. Most UPS units will also filter and regulate the utility power. A UPS can be used on most electronic equipment, although this article will focus mainly on it's use with computers.

There are basically three types of UPSs to choose from. Keep in mind that each manufacturer has their own design and changes. The types are as follows:

1. Offline (Standby) UPS

The standby UPS is the simplest and least expensive UPS design. Getting it's primary power from the AC line (ie. your outlet), this type of UPS switches over to the backup battery automatically when any drop in voltage is detected. When the power is restored, the UPS then switches back. This "no frill" UPS usually has nothing to regulate the electricity although a few manufacturers may include some sort of line filter.

Simplified Diagram of an "Offline" UPS

A "ferroresonant standby" UPS is an improvement on the design of the standby UPS. The ferroresonant UPS uses a ferroresonant transformer to switch from line power to battery power. By using this technology there is a source of stored energy that is used during that fraction of a second while the unit switches between line power and battery power. This was once one of the most common UPS designs, and are still made by some manufacturers. Today, most manufacturers have abandoned this design, claiming that it is inefficient, and favor the "online" UPS for models in the range of 1,000 VA or higher.

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