Liebert 610 Inverter, Output Regulation and Overload Performance, Non-Linear Load Characteristics

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Theory of Operation

2.2.4Inverter

The inverter is a solid state device that converts the DC output of the rectifier/charger or the battery to AC power.

Operation

The inverter converts DC power—from either the battery or the rectifier/charger—into three pulse- width-modulated/six-step waveforms. These waveforms are filtered into low-distortion sine wave power. The inverter is controlled by digitally controlled logic. This logic controls the precise synchro- nization, amplitude and frequency of the output voltage based on connected load characteristics.

In addition to the inverter efficiently supplying a regulated AC output from a DC source, the output isolation transformer acts as a second stage of isolation between the critical load bus and the commer- cial source power. The inverter is configured to handle most critical load inrush surges. It maintains output voltage Total Harmonic Distortion (THD) within specifications even when handling non-linear computer loads. Refer to Non-Linear Load Characteristics.

Output Regulation and Overload Performance

The inverter is capable of sustaining full output voltage (±2% of the nominal voltage) for up to 150% overload at the output for as long as 30 seconds without reducing the output voltage. It can also han- dle at least 125% of the rated current for up to 10 minutes and 104% of the rated current continu- ously. If an overload exceeds the system capacity and a bypass source is available, the critical load is transferred to the bypass source and the inverter is disconnected from the load. Refer to 3.5 - Auto- matic Operations.

Non-Linear Load Characteristics

Computers and computer equipment with switch-mode power supplies (SMPS) may generate non-lin- ear currents rich in fifth and seventh harmonics.

The inverter pulse-width-modulated/six-step waveform, coupled with the output filter, provides a nat- ural path for reducing the fifth and seventh harmonic currents produced by the load. The inverter/fil- ter limits the output voltage THD to less than 5% with up to 100% typical electronic data processing (EDP) loads. EDP equipment characteristically includes both non-linear and linear load components.

Unbalanced Load Characteristics

Unbalanced loads are actively regulated. The phase-to-phase voltage balance is maintained to within 2%, even with a 50% load imbalance.

The three-phase, root mean square (RMS) average voltage is also regulated through a separate con- trol circuit using phase-to-phase sensing.

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Contents Series 610 UPS Battery Cabinet Precautions Table of Contents Specifications MaintenanceFigures Tables Important Safety Instructions System Description Designed for Success ReliabilityOther Factors to Consider Safety Precautions Modes of Operation Operator Controls Options Automatic Restart Customer Alarm InterfaceTemperature-Compensated Charging Battery Load TestingGeneral Component Descriptions Battery PlantUPS Module Controls Hardware Detailed Component DescriptionsSoftware Input Circuit Breaker Input Power FactorRectifier/Charger OperationBattery Equalize Charge Circuit Battery Charging CircuitBattery Disconnect Battery Charge Current LimitingOutput Regulation and Overload Performance Non-Linear Load CharacteristicsUnbalanced Load Characteristics InverterPulsed Parallel Operation Static Switch Backfeed ProtectionStatic Bypass Bypass Circuit BreakerTransfer and Retransfer Conditions Three Breaker Maintenance Bypass Switchboard Display Screen and Operator Controls Features100kVA 500kVA 1000kVA Description Function Operator controls, typical systemDescription Function Series 610 UPS operator control panelMenu tree Menu Tree NavigationMaster menu screen Master Menu ScreenOperation Input Metering Displays Monitor/Mimic Display ScreenOutput Metering Displays Item 7 Alarm Messages Status/Alarm Message AreasItem 6 Status Messages Monitor/Mimic display example Utility fail Walk-in display screen Walk-In Display ScreenStatus reports screen Status Reports ScreensEvent History Present StatusHistory status report screen History StatusSystem Status Battery Cycle MonitorBattery cycle monitoring summary screen System configuration screens System Configuration ScreensMaximum auto-retransfer attempts screen Maximum Auto-Retransfer AttemptsDate screen DateTime screen TimeAuto dial screen Auto DialSystem Options Language SelectionContinuous Duty Static Switch Optional Standard Remote Monitor Indications Channel Alarm messagesAdditional alarm messages Remote MonitorLow Battery Alarm Limit Settings ScreenOverload Alarm Battery DischargingTemperature Limit Setting Optional Battery Shutdown 60 MinutesBattery Rating 100% Battery RatingLoad transfer procedure screen Load Transfer Procedures ScreenRefer to 3.4.1 Start-Up Procedure for more details Start-Up Procedures ScreenBattery Time Screen Shutdown Procedures ScreenBattery time screen 15-minute discharge Elapsed Time Minutes Upper Limit Actual Lower LimitStatus Reports Screens Meter Calibration ScreenBattery equalize screen Battery Equalize ScreenAlarm and status message screen Alarm and Status Messages Status MessagesAbbreviations used in alarm messages Alarm MessagesAC Input Alarm messages and corrective actionsUPS System Cooling UPS SystemAlarm Message Special Functions Alarm messages-summaryWorldwide Reporting Communication InterfacesAuto-Dial Requesting Information Local Reporting to a TerminalLocal Reporting to a Monitor Site Reporting SiteScan or SnmpKeys Function Series 610 terminal commandsRemote Monitor Panel Separate / Simultaneous OutputsCircuit breaker abbreviations Load on BypassAbbreviation Circuit Breaker Load on bypass UPS available OK to TransferLoad on UPS bypass available Momentary Overloads Momentary overload through pulse-parallel static switchInput power fail-load on battery Input Power Failure-Load on BatteryLoad on UPS-battery not available Off BatteryEmergency Module Off Refer to 3.4.4 Shutdown ProceduresEmergency power off Remote Emergency Power OffModule Shutdown Refer to 3.3.9 Maintenance BypassLoad on maintenance bypass two breakers Load on maintenance bypass three breakers Start-Up Procedure Manual ProceduresStart-Up Procedure Set the Static Switch Disconnect or to OFF open Start-up procedures Start-Up Procedure Load transfer procedures screen Load Transfer ProceduresMaintenance Bypass Load Transfers Shutdown Procedures Shutdown Procedures Module Shutdown ProcedureLocal Emergency Modules Off Lemo Remote Emergency Power Off RepoBattery exercise control screen above and results below Battery Exercise Procedures150% Automatic OperationsOverloads Without Transfer 1000%Automatic Retransfers to UPS Automatic Transfers to Bypass Overload ConditionAutomatic Transfers to Bypass UPS System Faults Enabling Automatic Restart Automatic Restart OptionalSequence of Operation Maintenance Training Liebert Global ServicesMaintenance Agreements The Signature Program Professional Start-UpRecord Log Routine MaintenanceAir Filters Limited Life Components Battery Safety Precautions Battery MaintenanceAvertissement Number of Cells Battery Voltage VDC Nominal Float Matching Battery Cabinets OptionalBattery voltage record Battery retorque valuesRack-Mounted Batteries Detection of Trouble Torque specifications unless otherwise labeledTorque Requirements Recommended Test Equipment Reporting a ProblemUpstream Feeder Circuit Breaker Setting Inspections Corrective ActionsRating Power factor pf KVAKVA Environmental Conditions Specifications applicable to environmentBattery Operation AdjustmentsElectrical Specifications Page United States Technical Support/ServiceCompany Behind the Products Locations
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