An uninterruptible power supply (UPS) can be used at sites where system downtime due to AC disturbances must be minimized. The UPS uses batteries to generate AC to its load when various types of AC input disturbances occur. The duration of UPS support time depends upon the relationship between UPS capacity and output loading.

The decision to provide alternate power sources, standby power generation, UPS, or a combination of these should be based on the economic consequences of system interruption due to power outages or brownouts (low voltages). The Unisys service representative can assist in this area.