UPS
Edit Watch this page Read in another language Uninterruptible power supply Page issues A small free-standing UPS with one IEC 60320 C14 input and three C13 outputs A large datacenter-scale UPS being installed by electricians An uninterruptible power supply , also uninterruptible power source , UPS or battery/flywheel backup , is a continual power system , an electrical apparatus that provides emergency power to a load when the input power source or 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 (only a few minutes) but sufficient to start a standby power source or properly shut down the protected equipment. A UPS is typically used to protect hard