Emerson 480V user manual Bypass Supplies, Operating Modes, Normal Mode, Battery Mode, Bypass Mode

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Operation

7.1.1Bypass Supplies

The Liebert NX contains an electronically controlled switching circuit that enables the critical load to be connected to either the inverter output or to a bypass power source via the static bypass line. Dur- ing normal system operation the load is connected to the inverter and the inverter contactor is closed; but in the event of a UPS overload or an inverter failure, the load is automatically transferred to the static bypass line.

To provide a clean (no-break) load transfer between the inverter output and static bypass line, the bypass static switch activates, connecting the load to bypass. To achieve this, the inverter output and bypass supply must be fully synchronized during normal operating conditions. This is achieved through the inverter control electronics, which make the inverter frequency track that of the static bypass supply, provided that the bypass remains within an acceptable frequency window.

A manually controlled, maintenance bypass supply is incorporated into the UPS design. It enables the critical load to be powered from the utility (bypass) supply while the UPS is shut down for routine maintenance.

NOTE

When the UPS is operating in bypass mode or on maintenance bypass, the connected equipment is not protected from power failures or surges and sags.

In dual input configuration, the neutrals of each source must be connected to each other, to guarantee that the dual source has the same voltage potential to earth.

7.1.2Operating Modes

The UPS is designed to operate as an on-line, double-conversion, reverse-transfer system in the fol- lowing modes:

Normal Mode

Operating in normal mode, the Liebert NX’s rectifier derives power from a utility AC source and sup- plies regulated DC power to the inverter, which regenerates precise AC power to supply the connected equipment. The rectifier also uses the utility source power to charge the batteries.

Battery Mode

When utility AC power fails, the Liebert NX protects the critical load by instantaneously channeling battery power to the inverter, which continues supporting the critical load without interruption. When utility power returns and is within acceptable limits, the Liebert NX automatically shifts back to Normal mode, with the rectifier powering the critical load.

Bypass Mode

When the Liebert NX is in bypass mode, the load is directly supported by utility power and is without battery backup protection.

The Liebert NX’s inverter static switch and bypass static switch will shift the load from the inverter to bypass mode without an interruption in AC power if the inverter is synchronous with the bypass and any of the following occurs:

inverter fails

inverter overload capacity is exceeded

inverter is manually turned off by the user

NOTE

If the inverter is asynchronous with the bypass, the static switch will transfer the load from the inverter to the bypass WITH interruption in AC power to the critical load. This interruption will be less than 10ms. This interruption time may be altered by modifying the Output transfer interrupt time setting.

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Contents Liebert NX UPS Page Table of Contents Operator Control and Display Panel UPS SpecificationsOptions Operating Instructions Pop-Up WindowsSpecifications and Technical Data Appendix a UPS Status MessagesTables Page Important Safety Instructions Battery Cabinet Precautions Glossary of Symbols Installation External InspectionsUPS Location Internal InspectionsPreliminary Checks Mechanical Considerations Battery LocationConsiderations in Moving the Liebert NX Special Considerations for Parallel SystemsCable Entry Floor InstallationClearances System CompositionCabinet arrangement-Liebert NX units and battery cabinets UPS Lug Size and Torque Requirements Power CablingCable Rating UPS Input Configuration Cabling GuidelinesCable Connections Input and output busbarsUPS Rectifier and Bypass Input Supply Safety GroundProtective Devices Common Input Connections Cabling ProcedureOutput System Connections-Ensure Correct Phase Rotation Dual Input ConnectionsControl Cables Frequency Converter ModeMonitor Board Features Dry Contacts Input Dry Contacts Maintenance Bypass Cabinet InterfaceMaintenance bypass cabinet interface Input dry contacts atBCB Control Interface BCB control interfaceOutput Dry Contacts Inverter mode relay centerMain input fault relay center Output dry contact relaysIndicates Pin EPO Input-OptionalEPO input contact relays Safety IntroductionExternal Battery Cabinet Installation Battery CabinetsInsulated Post Tray Handle For Cabling Connecting the BatteriesInstallation Considerations BCB Shunt Trip Connecting the Battery Cabinet to the UPSNon-Standard Batteries This power must be UPS protected Alber Monitoring System-OptionalPerformance Requirements LBS Cable and SettingsLoad Bus Synchronization LBS CableGeneral Configuring Parallel System OperationFeatures of Parallel System Operation Modes Summary Installing Parallel SystemOperating Principles Redundancy Paralleling Conditions for Parallel System Cabinet InstallationPower Cables Preliminary ChecksCables InterconnectingAuxiliary Dry Contact Cables To Load Q1Ext Q2ExtQByp Normally Open EPO Normally Closed EPOUPS mechanical characteristics UPS Mechanical CharacteristicsEnvironmental characteristics Conformity and StandardsUPS Electrical Characteristics UPS terminalRated Power kVA 100 120 Rectifier input powerLiebert approved replacement batteries Battery Manufacturer Models SuppliedBypass Input DC Intermediate CircuitInverter Output Left Side GND Left Side View Front View Max. Door Swing U3819205 530628 Pg , Rev BattExt Auxiliary Contacts External Battery CabinetBattery Breaker Top Top Front Right Side Front Rear SystemRear FRONTOutput Run From Conductors Ph A, B, C UPS Outputs Ph A, B, C System InputPh A, B, C UPS Inputs AC OutputGround UPS Utility UPS #1-UPS #4 Module AC Ph A, B, C UPS InputsPh A, B, C System Outputs Isometric View U3819301Single module block diagram dual input configuration General DescriptionBypass Mode Normal ModeBattery Mode Bypass SuppliesMaintenance Mode Parallel Redundancy Mode System ExpansionOperator Control Panel Display Panel LayoutMimic indicators Control buttons Navigation keys Detailed view of control panelMimic Display Indicators Mimic display status indicatorsControl Buttons Control buttonsAudible Buzzer LCD OverviewIcons for navigation keys Navigation KeysUPS System Information Description of items in UPS system windowLCD Menus and Data Items Mains Descriptions of UPS menus and data window itemsMenu Type Item Type Explanation InputTests Start/stop BatteryLanguage Selection Current Date and Time Set date and timeUPS Status Messages Current status and history log recordsOpening Display Default ScreenTypes of LCD Screens UPS Help Screen Screen Saver WindowPop-Up Windows Liebert NX Operating Modes UPS operating modesCircuit Breakers Circuit breakersUPS Startup Startup ProcedureIndicator State Switch from Normal Mode to Bypass Mode Switch from Bypass Mode to Normal ModeMaintenance Bypass Procedure and Powering Down the UPS Auto Restart Emergency Shutdown With EPOBattery Undervoltage Pre-Warning Battery ProtectionMulti-Module System Procedures Battery End-of-Discharge EOD ProtectionTie breaker Inserting One Module into a Multi-Module System LED Function StatusShutdown Procedure-Complete UPS and Load Shutdown Commissioning a Parallel SystemParallel System Start Up Analog Input Interface Power OutputCommunication and Other User Terminals Liebert IntelliSlot CommunicationComments See 10.1.5 ConfiguringLiebert NX communication options Baud RatesConfiguring Baud Rates Liebert IntelliSlot Web card display Relay Card Relay Card pin configurationRelay card jumper configuration Pin Function OperationPin Description MultiPort 4 CardAssignment Replacing Dust Filters Remote Alarm MonitorLBS Mode-Load Bus Synchronization Lug Size and Torque Requirements Torque specificationsBattery torque rating Cable Lengths Floor to Connection Point Inside UPSDistance to connection points on the Liebert NX UPS Parallel system current tableLead/Lag ratings External cabinet dimensions, including side panelsCable size and tightening torques 250 10 N*m Battery Run Times Estimated battery run time, minutesEvent Message Description / Suggested Action if any Services at 800-543-2378 for assistanceUPS status messages Bypass voltage exceeds the limit High ambient air temperatureBypass voltage is beyond the normal range Software according to the customer’s agreementInverter STS Fail Error can also leads to the alarmAlarm if applicable Condition is removedEmergency Power Off EPOUPS status messages UPS Status Messages Page Ti n Ne tIti That
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480V specifications

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