Eaton Power Xpert 9395C Installation And Operation Manual

88 Eaton Power Xpert 9395C UPS Installation and Operation Manual 164000821—Rev 06cabinet, no other cabinets or equipment are required for the single UPS to successfully support its appliedloads.66..22..11 MMooddeessThe 9395C-1100 UPS supports a critical load in different modes of operation:• In Online mode, the critical load is supplied by the inverter, which derives its power from rectified utility ACpower. In this mode, the battery charger also provides charging current for the battery, if needed.• In Energy Saver mode, commercial AC power is supplied directly to the critical load through the continuousstatic switch and transfers automatically to Online mode if an abnormal condition is detected. The EnergySaver mode requires a UPS with a continuous static switch.• In Bypass mode, the critical load is directly supported by utility power.• In Battery mode, the battery provides DC power, which maintains inverter operation. The battery supportsthe critical load.The following paragraphs describe the differences in the five UPS operating modes, using block diagrams toshow the power flow during each mode of operation.66..22..22 OOnnlliinnee MMooddeeFigure 54 shows the path of electrical power through the UPS system when the UPS is operating in Onlinemode.During normal UPS operation, power for the system is derived from a utility input source through the rectifierinput contactor K1. The front panel displays “Online,” indicating the incoming power is within voltage andfrequency acceptance windows. Three-phase AC input power is converted to DC using IGBT devices toproduce a regulated DC voltage to the inverter. When battery breaker is closed the battery is charged directlyfrom the regulated rectifier output through a buck or boost DC converter, depending on the system voltage andthe size of the battery string attached to the unit.The battery converter derives its input from the regulated DC output of the rectifier and provides a buckedregulated DC voltage charge current to the battery. The battery is always connected to the UPS and ready tosupport the inverter should the utility input become unavailable.The inverter produces a three-phase AC output to a customer's load without the use of a transformer. Theinverter derives regulated DC from the rectifier and uses IGBT devices and pulse-width modulation (PWM) toproduce a regulated and filtered AC output.Understanding UPS Operation