Flickering lights can be a "charming" feature of an old house. For any business that experiences such losses of power, however, this charming feature can be quite problematic.

Uninterruptible power supplies (UPS) are designed to protect electronic equipment like computers and phone systems against problems stemming from a temporary failure in the power supply. By providing a constant source of electricity, a UPS can help prevent damage or data loss that can occur with the unexpected shutdown of computers, phone systems, and other sensitive equipment.

UPS systems work by detecting decreases in the amount of electricity coming from the wall circuit, and boosting power to maintain a constant flow of electricity to connected equipment. This power boost is provided either by a transformer that enhances a weak electrical flow, or from an internal battery that substitutes for the normal power source in the event of failure.

Most UPS units also contain surge protectors, which help prevent equipment damage whenever there are power surges (sudden increases in the flow of voltage).

This guide is designed to give you the facts you need to purchase a UPS system for your business. The various sections are listed in the box to the right. You can choose to read this guide from beginning to end, or jump directly to a section of interest.