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Uninterruptible Power Supply (UPS)

An uninterruptible power supply, also uninterruptible power source, UPS or battery/flywheel backup, is an electrical apparatus that provides emergency power to a load when the input power source, typically mains power, fails. A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide near-instantaneous protection from input power interruptions, by supplying energy stored in batteries, supercapacitors, or flywheels. The on- battery runtime of most uninterruptible power sources is relatively short but sufficient to start a standby power source or properly shut down the protected equipment. A UPS is typically used to protect hardware such as computers, data centers, telecommunication equipment or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss. UPS units range in size from units designed to protect a single computer to large units powering entire data centers or buildings. The primary role of any UPS is to provide short-term power when the input power source fails. However, most UPS units are also capable, in varying degrees, of correcting common utility power problems, such as: - voltage spike or sustained over-voltage - momentary or sustained reduction in input voltage - noise, defined as a high frequency transient or oscillation, usually injected into the line by nearby equipment - instability of the mains frequency - harmonic distortion: defined as a departure from the ideal sinusoidal waveform expected on the line There are a variety of UPS types and design approaches which are used to implement UPS systems, each with distinct performance characteristics. The most common design approaches are: • Standby • Line Interactive • Standby-Ferro • Double Conversion On-Line • Delta Conversion On-Line Standards EN 62040-1:2008 Uninterruptible power systems (UPS) – Part 1: General and safety requirements for UPS EN 62040-2:2006 Uninterruptible power systems (UPS) – Part 2: Electromagnetic compatibility (EMC) requirements EN 62040-3:2011 Uninterruptible power systems (UPS) – Part 3: Method of specifying the performance and test requirements EN 62040-4:2013 Uninterruptible power systems (UPS) - Part 4: Environmental aspects - Requirements and reporting