This specification covers semiconductor indirect a.c. convertor systems that have electrical energy storage means in the d.c. link. The primary function of uninterruptible power systems covered by this specification is to ensure continuity of an alternating power source to critical loads. An uninterruptible power system (UPS) also serves to improve the quality of the power source by keeping it within the specified characteristics.
2 This specification covers the type of UPS that basically consists of a rectifier, a storage battery and a static inverter. The rectifier operates from the a.c. supply mains to provide d.c. power for operation of the inverter and to maintain the battery in a state of charge. The battery serves as the d.c. energy source for the inverter during a.c. supply mains outages. The inverter converts the d.c. power from the rectifier or from the battery to provide an alternating power source to the critical load.
3 The systems covered by this specification are suitable for connection to an a.c. source of supply that has a nominal frequency of 50 Hz and a nominal voltage of 230 V (single-phase two-wire system), or 400 V (three-phase four-wire system), or 525 V (three-phase three-wire system), in accordance with the voltage designation specified in SANS 1019.
4 The specification covers UPS's designed for use under the following normal service conditions: