This Practice and the purchaser's PIP ELSAP04-D Data Sheet describe the minimum requirements for design, fabrication, inspection, testing, shipment, and documentation for a complete on-line, UPS system of either a pulse width modulated (PWM) or ferroresonant type. A PWM-type UPS system includes a rectifier/charger, inverter, static bypass switch, manual bypass switches, transformers, and accessories. A ferroresonant-type UPS system includes a rectifier/charger, inverter, constant voltage or ferroresonant transformer, static bypass switch, manual bypass switches, transformers, and accessories.