The primary function of the UPS covered by this standard is to ensure continuity of an a.c.power source. The UPS may also serve to improve the quality of the power source by keepingit within specified characteristics. UPS have been developed over a wide range of power, fromless than hundred watts to several megawatts, to meet requirements for availability andquality of power to a variety of loads. Refer to Annexes A and B for information on typicalUPS configurations and topologies.