The Use of the UPS Systems in the CERN Power Distribution

The un-interruptible power supply (UPS) provides an increased supply reliability. It provides a no-break commutation to a battery in case of mains fault, and it provides a defined time for shut-down of critical installations. UPS systems are in service all over CERN, mainly supplying computer systems, control systems and other systems linked to safety. For the LHC the systems protecting the machine in case of quenching of supraconducting elements will require practically fail-safe installations. The desired degree of reliability and availability will be achieved by the use of UPS systems, grouped to assure a sufficient level of redundancy