Eaton Power Xpert 9395C Installation And Operation Manual

Eaton Power Xpert 9395C UPS Installation and Operation Manual 164000821—Rev 06 89Figure 54. Path of Current Through the UPS in Online ModeStaticSwitchretrevnIreifitceRBatteryConverterBatteryBatteryBreakerMain Power FlowTrickle CurrentEnergizedDe-EnergizedStaticSwitchretrevnIreifitceRMain Power FlowTrickle CurrentEnergizedDe-EnergizedBypass InputRectifierInput OutputK1ClosedOpenBreakers ContactorsIf the utility AC power is interrupted or is out of specification, the UPS automatically switches to Battery modeto support the critical load without interruption. When utility power returns, the UPS returns to Normal mode.If the UPS becomes overloaded or unavailable, the UPS switches to Bypass mode. The UPS automaticallyreturns to Normal mode when the overload condition is cleared and system operation is restored withinspecified limits.If the UPS suffers an internal failure, it switches automatically to Bypass mode and remains in that mode untilthe failure is corrected and the UPS is back in service.66..22..33 EEnneerrggyy SSaavveerr SSyysstteemm ((EESSSS)) MMooddeeWhen the UPS is operating in ESS mode, commercial AC power is supplied directly to the critical load throughthe continuous static switch. Power line filtering and spike protection for the load are provided by the input andoutput filter networks, and the UPS actively monitors the critical bus for power disturbances. When in thismode, the input contactor is closed and the link is maintained through the diode bridge.If commercial power voltage or frequency disturbances are detected, the system forward transfers to Batterymode for minor disturbances and then to double-conversion mode for more severe disturbances. During acomplete power outage, the transfer takes place within 2 ms to ensure loads being fed by the system outputare not interrupted. All forward transfers transfer to Battery mode before returning to double-conversion mode.In High Alert mode the unit transfers from ESS mode to double-conversion mode or if in double-conversionmode remains in double-conversion mode for a default time period of one hour (customer configurable). At thecompletion of the time period, the unit defaults back to ESS mode. If the High Alert command is receivedduring the time period, the timer will be restarted.ESS mode is a normal operating mode, and not an alarm condition. While the UPS is in this mode, the Onlinelight on the front display will illuminate.Understanding UPS Operation