An Uninterruptible Power Supply (or UPS) is a battery backup device for electronic equipment. A UPS provides protection to servers, workstations, network, banking and security systems and other electronic equipment from electrical disturbances. Positioned between the incoming utility power and the electrical equipment connected to it, the UPS filters the power to eliminate any spikes or surges that may cause damage to the computer or the data it is processing. Many UPSs offer a software component that enables you to automate backup and shut down procedures in case there's a power failure A UPS is essential in preventing unnecessary downtime caused by momentary power outages or blackouts. UPS solutions are classified according to their power output capacity: Volt Amperes (VA). When specifying a server or other mission-critical equipment, add a UPS to the configuration.
There are two basic types of UPS systems: standby power systems (SPSs) and on-line UPS systems. An SPS monitors the power line and switches to battery power as soon as it detects a problem. The switch to battery, however, can require several milliseconds, during which time the computer is not receiving any power. Standby Power Systems are sometimes called Line-interactive UPSs.
An on-line UPS avoids these momentary power lapses by constantly providing power from its own inverter, even when the power line is functioning properly. In general, on-line UPSs are more expensive than SPSs.