This Standards Publication covers uninterruptible power systems (UPS) as it applies to semiconductor ac to ac converter systems with a dedicated dc electrical energy storage capability. The primary function of the UPS covered by this technical standard is to provide quality and continuity of an alternating current power source. This UPS standard can be applied to a UPS that is comprised of semiconductor power converters and rotary power converters (motor-generated sets); however@ no technical or application information regarding rotary power converters is includedin this publication. The UPS standard is intended to define a complete Uninterruptible Power System regarding its overall performance and safety and not individual subsystem functional units.