CPE Division G Inc. 2011 Providers of Sales & Service of Quality Power Protection Equipment for over 25 Years A UPS or uninterruptible power supply is an electrical device that provides emergency power to a load, or electrical equipment when the input power source, typically the utility mains, fails.  A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide instantaneous or near-instantaneous protection from input power interruptions by means of one or more attached batteries and associated electronic circuitry for lower power users, and by means of diesel generators and flywheels for high power users.  The on-battery runtime of most uninterruptible power sources is relatively short - 5 to 15 minutes being typical for smaller units, but sufficient to allow time to bring an auxiliary power source on line, or to properly shut down the protected equipment. While not limited to protecting any particular type of equipment, a UPS is typically used to protect computers, data centres, telecommunication equipment of other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption and/or loss of data.  UPS units range in size from units designed to protect a single computer to large units power data centres, buildings or even entiire cities.