Eaton 9E Installation And Operation Manual

Also see for 9E: Installation and operation manual Installation and operation manual Installation and operation manual Manual Manual

Contents

Understanding UPS OperationEaton 9E UPS (20–30 kVA, 208/220V) Installation and Operation Manual 164202124—Rev 2 www.eaton.com/powerquality 5-55.2.5 Battery ModeThe UPS automatically transfers to Battery mode if a utility power outage occurs, or if the utility power doesnot conform to specified parameters. In Battery mode, the battery provides emergency DC power that theinverter converts to AC power.Figure 5-4 shows the path of electrical power through the UPS system when operating in Battery mode.Figure 5-4. Path of Current Through the UPS in Battery ModeDuring a utility power failure, the rectifier no longer has an AC utility source from which to supply the DC outputvoltage required to support the inverter. The input relay opens and the battery instantaneously supplies energyto the battery converter. The converter boosts the voltage so that the inverter can support the customer's loadwithout interruption. If bypass is common with the rectifier input, the backfeed protection relay also opens. Theopening of the input and the backfeed protection relays prevent system voltages from bleeding backwardsthrough the static switch and rectifier snubber components to the utility source.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 connected loads. When this event occurs, the UPS issues another set of audible and visual alarmsindicating SHUTDOWN IMMINENT. Unless the rectifier has a valid AC input soon, the output can be supportedfor only two minutes before the output of the system shuts down. If the bypass source is available, the UPStransfers to bypass instead of shutting down.If at any time during the battery discharge the input power becomes available again, the input and the backfeedprotection relays close and the rectifier begins to supply DC current to the converter and inverter. At this point,the unit returns to Normal mode. Depending on the total load and the duration of the battery discharge, batterycurrent limit alarms may be seen for a short time due to the current required to recharge the battery.Bypass Input StaticSwitchBackfeedProtection RelayRectifier InverterOutputRelayInputRelayInputBreakerRectifierInput OutputBatteryConverterBatteryRelayMain Power FlowRelaysBreakersClosedOpenBatteryTrickle CurrentDe-EnergizedEnergized