Eaton Power Xpert 9395C Installation And Operation Manual

Eaton Power Xpert 9395C UPS Installation and Operation Manual 164000821—Rev 06 99this operating mode until the input power to the rectifier is again within the specified voltage or frequencyacceptance windows.If the input power fails to return or is not within the acceptance windows required for normal operation, thebattery continues discharging until a DC voltage level is reached where the inverter output can no longersupport the shared loads. When this event occurs, each UPS issues another set of audible and visual alarmsthat indicate a two-minute SHUTDOWN IMMINENT warning. Unless the system has a valid AC input soon,redundant UPMs begin shutting down until there are no longer enough UPMs online to support the connectedload. When this event occurs, the system shuts down. If the bypass source is available, the system transfers tobypass instead of shutting down.Figure 61. Path of Current through the UPSs in Battery Mode – Distributed BypassMain Power FlowUPS 1UPS 2Output toCritical LoadBatteryUPS Input Tie CabinetUPS 1 OutputUPS 2 OutputBatteryClosedOpenBreakersIf at any time during the battery discharge the input power becomes available again, the rectifier begins tosupply DC current to the inverter. At this point, the UPS returns to Normal mode. If at any time during thebattery discharge the AC input power becomes available again, each rectifier turns on, assumes the inverterload from the batteries, and begins recharging the batteries. Depending on the total load and the duration of thebattery discharge, battery and rectifier input current limit alarms may be seen for a short time due to the currentrequired to recharge the batteries.66..55 MMuullttiippllee UUPPSS DDiissttrriibbuutteedd BByyppaassss SSyysstteemm OOnneelliinnee CCoonnffiigguurraattiioonnssThe distributed bypass system oneline drawings in this section show the simplified internal structure of theUPS, battery supply, and basic maintenance bypass in a multiple UPS configuration. These onelines representeach UPS in the distributed bypass system.Understanding UPS Operation