Uninterruptible power supplies work by converting battery power to power that can be used by the computer system. A computer system plugs into the uninterruptible power supply, which then plugs into a wall outlet. If the power goes off or the voltage running to the computer system fluctuates, the uninterruptible power supply maintains a steady stream of acceptable power to the computer system.
There are two types of uninterruptible power supplies. A standby uninterruptible power supply only converts battery power to electricity when it is needed. A continuous uninterruptible power supply constantly converts battery power to electricity, recharging the battery as it operates. Standby uninterruptible power supplies are most often used in homes and offices due to their smaller operating cost. Continuous uninterruptible power supplies are used in server rooms or for large computer systems due to their cleanness and stability.
Various features are included on an uninterruptible power supply. Most are floor models since the included batteries are heavy, making the unit difficult to hang. There is usually a power button on the front of the unit. More expensive models may include LCD screens that report information on the charge of the battery and the status of the power usage.