This part of IEC 62040 establishes the performance and test requirements applied to movable, stationary and fixed electronic d.c. uninterruptible power systems (d.c. UPS) that: - are supplied from an a.c. voltage source not exceeding 1 000 V; - deliver a d.c. output voltage not exceeding 1 500 V; - incorporate an energy storage device and - have a primary function to ensure continuity of d.c. power to loads. This part of IEC 62040 specifies performance and test requirements of a complete UPS and not of individual UPS functional units. The individual UPS functional units are dealt with in IEC publications referred to in the bibliography that apply so far that they are not in contradiction with this International Standard. UPSs have been developed over a wide range of power, from less than a hundred watts to megawatts, to meet requirements for availability and quality of power to a variety of loads. Refer to Annexes A and B for information on typical UPS configurations and topologies. This International Standard also includes UPS performance and test requirements related to interrupters, isolating switches, and tie switches, if any, which are integral to the UPS. These components interact with other functional units of the UPS to maintain continuity of load power. This standard does not cover: conventional a.c. input distribution boards and their associated switches; " conventional d.c. distribution boards and their associated switches; " conventional a.c. UPSs covered by IEC 62040-3; " low-voltage d.c. power supply devices covered by a specific product standard e.g. IEC 61204 and " systems wherein the output voltage is derived from a rotating machine. Note 1: This standard recognises that power availability to information technology (IT) equipment represents a major UPS application. The UPS output characteristics specified in this standard are therefore also aimed at ensuring compatibility with the requirements of IT equipment. This, subject any limitation stated in the manufacturer s declaration, includes requirements for steady state and transient voltage variation as well as for the supply of both resistive and constant power load characteristics of IT equipment. Note 2: Test loads specified in this standard simulate both resistive and constant power load characteristics. Their use is prescribed with the objective of verifying design and performance, as declared by the manufacturer, and also of minimising any complexity and energy consumption during the tests.