Eaton 93E UPS 15-80 kVA (380/400/415 V) Installation and Operation Manual© Eaton Corporation plc 2015. All rights reserved. Revision: 001 Document ID: 614-01975-00 74 (133)6.2.1 ModesThe Eaton 93E UPS supports a critical load in four different modes ofoperation:• In the standard normal mode, the critical load is supplied by theinverter, which derives its power from rectified utility AC power. Inthis mode, the battery charger also provides charging current for thebattery, if needed, the standard mode is the standard normaloperating mode.• In the high-efficiency (HE) mode, commercial AC power is supplieddirectly to the critical load through the internal bypass. If anabnormal condition is detected, the UPS transfers automatically tothe standard normal mode (double-conversion on demand).• In the bypass mode, the critical load is supported by the bypasssource.• In the battery mode, the battery provides DC power, whichmaintains inverter operation. The battery supports the critical load.The following sections describe the differences in the UPS operatingmodes, using block diagrams to show the power flow during each modeof operation.6.2.2 Standard normal modeDuring the standard normal mode, power for the system is derived froma utility input source through the rectifier input relay. 3-phase AC inputpower is converted to DC using IGBT devices to produce a regulated DCvoltage to the inverter. When the battery relay is closed, the battery ischarged directly from the regulated rectifier output through a buck orboost DC converter, depending on the system voltage and the size ofthe battery string attached to the unit.Figure 30 shows the path of electrical power through the UPS systemwhen the UPS is operating in the normal mode.
