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Fluke 5725A instruction manual AC Line Voltage Selection Section, 4-60

Models: 5725A

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Theory of Operation 4

Detailed Circuit Description

AC Line Voltage Selection Section

4-60.

In addition to the primary power switch, S401, this section contains three line-voltage selection switches, S402 through S404. These three switches allow the 5725A to be set to eight nominal ac line voltage levels, each with a 10% tolerance.

Thermistors RT401 and RT402 have negative temperature coefficients, and limit inrush current at power-up. Relay K401 provides a pair of shunt switches to bypass thermistors after about a half second. This allows greater efficiency than with thermistors alone, and the use of thermistors allows operation if the relay fails. CR401 through CR404 and C401 form an unregulated power supply that is not isolated from ac line power for controlling K401. R401, R402, and C402 provide a time delay that prevents Q401, and hence K401 from switching before the effective power supply capacitance is sufficiently charged.

Metal Oxide Varistor RV401 prevents high voltage transients on the ac line from reaching the transformer by clamping voltages above 275V ac.

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Fluke 5725A instruction manual AC Line Voltage Selection Section, 4-60

Contents

Amplifier 5725AInstruction Manual Page Table of Contents Theory of Operation 5725ACalibration and Verification Instruction Manual 5725ATitle List of TablesTable Instruction Manual 5725ATitle List of FiguresFigure Instruction Manual 5725Aviii Bescheinigung des Herstellers/Importeurs Interference InformationDeclaration of the Manufacturer or Importer Page Terms in this Manual OPERATOR SAFETY SUMMARYHIGH VOLTAGE LETHAL VOLTAGEUse the Proper Fuse Symbols Marked on EquipmentPower Source Use the Proper Power CordUse Care When Servicing With Power On SERVICING SAFETY SUMMANYFOR QUALIFIED SERVICE PERSONNEL ONLY Do Not Service AloneNever Accept Ordinary and General Tests for Death FIRST AID FOR ELECTRIC SHOCKFree the Victim From the Live Conductor Get HelpChapter Introduction and SpecificationsInstruction Manual 5725AIntroduction Where to Go From Here 5700A Operator Reference Guide How to Use the Manuals5725A Instruction Manual 5700A Operator Manual5700A Service Manual Specifications±5C from calibration temperature Introduction and SpecificationsSpecifications DC Voltage Range ResolutionAC Voltage 5725AInstruction Manual AC Voltage continued Introduction and SpecificationsSpecifications Voltage Range 5725AInstruction Manual AC Voltage continuedTemperature Introduction and SpecificationsSpecifications ±5C from calibration temperatureNote5725A Instruction Manual Two-WireCompFour-Wire Four-WireDC Current Introduction and SpecificationsSpecifications AC Current 5725AInstruction Manual AC Current continued Introduction and SpecificationsSpecifications Instruction Manual ResolutionResolution 5725ATemperature performance: Operating: 0C to 50C Introduction and SpecificationsSpecifications General SpecificationsInstruction Manual 5725AConnecting to the 5700A Calibrator InstallationService Information Placement and Rack MountingInstruction Manual 5725AIntroduction Unpacking and InspectionInstallation VOLTAGE/CURRENT 5725AInstruction Manual TYPEService Information Service InformationPlacement and Rack Mounting Cooling ConsiderationsFigure 2-2.Correct Way to Dress Interface Cable Connecting to the 5700A CalibratorSelecting Line Voltage Selecting Line VoltagewCaution Accessing the FuseConnecting to Line Power Connecting to Line PowerInstruction Manual 5725AChapter Operating NotesInstruction Manual 5725AOperating Notes Introduction5725A Front Panel FeaturesFigure 3-1.Front Panel Features POWER5725A STANDBY Indicator A B C D E F G HRear Panel Features Table 3-1.Front Panel FeaturesInstruction Manual Rear Panel FeaturesFigure 3-2.Rear Panel Features 5725A5700A CALIBRATOR Connector A B C D E F G H ITable 3-2.Rear Panel Features CALIBRATION SwitchWarm Up Turning on the 5725A AmplifierStandby 5725A Operating Functions and ModesVoltage Standby 5725A Operating Functions and Modes Current Standby3-10 Voltage OperateConditions That Activate the 5725A Current Operate3-11 3-12 Conditions That Activate the 5725AChapter Theory of OperationHigh Voltage Amplifier Feedback High Voltage Sense Assembly A6High Voltage Amplifier A3 High Voltage Heat Sink AssembliesIntroduction Overall Functional DescriptionInstruction Manual Figure 4-1.5725A Overall Block Diagram5725A 1100V AC Range Functional Description 11A Range Functional Description Voltage Standby Operation in the 11A DC RangeOperation in the 11A AC Range Voltage and Current Standby Modes4-11 How the 5700A and 5725A Communicate4-10 Description of the Out-GuardLines 5725A Side4-12 Description of the In-GuardLines4-13 Functional Summaries by Assembly4-15 Interconnect Assembly A1Detailed Circuit Description 4-144-16 Power Supply Assembly A4REF DES High Voltage Supply Section4-17 ASSEMBLY4-18 Switching Section4-20 Current-LimitSection4-19 System Supply Section4-22 Digital Assembly A5Fan Supply Section 4-21aq19f.eps Figure 4-2.Digital Assembly Block DiagramTheory of Operation Detailed Circuit Description4-27 EEROM4-26 Data LatchBreak-DetectCircuitry Power Up and Reset CircuitryWatchdog Timer Current Amplifier Assembly A2aq20f.eps 5725AInstruction Manual 4-35 Error Amplifier Section4-37 Output Stage Section4-36 Monitor Section4-39 Control and Switching SectionPower Supply Section 4-384-41 High Voltage Amplifier A34-40 Input Amplifieraq22f.eps Theory of OperationDetailed Circuit Description 4-43 Integrator4-42 Window Comparator4-46 Transconductance and Cascode Stage4-45 Midstage4-50 Autobias Current Source4-49 Autobias Sense Circuit4-51 Signal TransformersTemperature Monitoring High Voltage Amplifier Feedback4-54 High Voltage Sense Assembly A6aq21f.eps Theory of OperationDetailed Circuit Description 4-55 Sense Amplifier Section±3.2V during calibration STANDBY VOLTAGE LIMITS1 Analog Monitor Section4-56 SIGNAL4-58 Analog Input Switching SectionSerial Interface/Guard Crossing Section 4-574-59 Control Section4-60 AC Line Voltage Selection SectionInstruction Manual 5725AChapter Calibration and VerificationInstruction Manual 5725ACalibration and Verification Where to Find Further InformationIntroduction Instruction Manual 5725AChapter MaintenanceInstruction Manual 5725AIntroduction Replacing the FuseCleaning the Air Filter General Cleaning General CleaningCleaning PCA’s B. BOTTOM VIEW Access ProceduresFigure 6-3.Assembly Location Diagram A. TOP VIEWwWarning Initial Access ProcedureHIGH VOLTAGE Accessing the Digital Assembly A5 Accessing the Power Supply Assembly A4Instruction Manual WHEN REINSTALLING DIGITAL ASSEMBLYFigure 6-5.Accessing the Digital Assembly 5725A6-10 Accessing the Current Amplifier Assembly A2Figure 6-6.Correct Way to Dress Cables Accessing the High Voltage Amplifier A36-11 6-12 Accessing the High Voltage Sense Assembly A66-14 Accessing the High Voltage Output TransistorsAccessing the Interconnect Assembly A1 6-136-15 Enabling Front or Rear Binding Posts9.Reinstall the top cover Chapter TroubleshootingInstruction Manual 5725AIntroduction 5725A Fault CodesSelf Diagnostics MESSAGE Table 7-1.5725A Fault CodesFAULT 5725A Instruction ManualMESSAGE Self DiagnosticsTable 7-1.5725A Fault Codes cont FAULTManual Tests for Fault Isolation MESSAGE Manual Tests for Fault IsolationTable 7-2.Analog Monitor Faults FAULT NOProblem 5 Fault When Entering Current Operate Reduced-VoltageTroubleshooting ModeProblem 3: Fault When Entering Voltage Operate Problem 4: Fault When Entering Current StandbyTesting the Power Supply By Itself Testing the Power Supply By Itself7-10 Instruction Manual 5725AChapter List of Replaceable PartsInstruction Manual 5725AIntroduction How to Obtain PartsManual Status Information Newer Instruments5725A Service CentersAssembly Name Table 8-1.Final AssemblyList of Replaceable Parts Table 8-1.Final Assembly contaq24f.tif Figure 8-1.Final Assembly5725A aq25f.tif Figure 8-1.Final Assembly contList of Replaceable Parts aq26f.tif Figure 8-1.Final Assembly cont5725A Instruction Manualaq27f.tif Figure 8-1.Final Assembly contList of Replaceable Parts aq28f.tif Figure 8-1.Final Assembly cont5725A Instruction Manualaq29f.tif Figure 8-1.Final Assembly contList of Replaceable Parts aq30f.tif Figure 8-1.Final Assembly cont5725A Instruction Manualaq31f.tif Figure 8-1.Final Assembly contList of Replaceable Parts Table 8-2.A1 Interconnect PCA 5725Aaq36f.eps List of Replaceable Parts5725A-1611 Figure 8-2.A1 Interconnect PCATable 8-3.A2 Current Amplifier PCA 5725AInstruction Manual Table 8-3.A2 Current Amplifier PCA cont List of Replaceable PartsReference Description Designator 5725AInstruction Manual Table 8-3.A2 Current Amplifier PCA contaq37f.eps List of Replaceable Parts5725A-1650 Figure 8-3.A2 Current Amplifier PCATable 8-4.A3 High Voltage Amplifier PCA 5725AInstruction Manual Designator List of Replaceable PartsTable 8-4.A3 High Voltage Amplifier PCA cont R640,R642 5725AInstruction Manual Table 8-4.A3 High Voltage Amplifier PCA contaq38f.eps List of Replaceable Parts5725A-1661 Figure 8-4.A3 High Voltage Amplifier PCAInstruction Manual Table 8-5.A4 Power Supply PCA5725A List of Replaceable Parts Table 8-5.A4 Power Supply PCA contR351 R355 R361,R362 Table 8-5.A4 Power Supply PCA cont5725A Instruction Manualaq39f.eps Figure 8-5.A4 Power Supply PCAList of Replaceable Parts 5725A-1631Table 8-6.A5 Digital PCA 5725AInstruction Manual aq40f.eps List of Replaceable Parts5725A-1650 Figure 8-6.A5 Digital PCATable 8-7.A6 High Voltage Sense PCA 5725ATable 8-7.A6 High Voltage Sense PCA cont List of Replaceable PartsR154 R155 R156,R158,R168 R173 R162 R171 R172,R175 5725AInstruction Manual Table 8-7.A6 High Voltage Sense PCA contaq41f.eps List of Replaceable Parts5725A-1601 Figure 8-7.A6 High Voltage Sense PCAInstruction Manual Table 8-8.A12 Transformer Enclosure Assembly5725A aq32f.tif Figure 8-8.A12 Transformer Enclosure AssemblyList of Replaceable Parts aq33f.tif 5725Aaq34f.tif List of Replaceable Partsaq35f.tif 5725AInstruction Manual Figure 8-9.A30 Inductor PCA List of Replaceable PartsTable 8-9.A30 Inductor PCA 5725A-16035725A Chapter Schematic DiagramsInstruction Manual 5725Aaq48f.eps Schematic Diagrams5725A-1611 Figure 9-1.A1 Interconnect PCAFigure 9-1.A1 Interconnect PCA cont 5725AInstruction Manual Figure 9-1.A1 Interconnect PCA cont Schematic Diagrams5725A-1650 5725AInstruction Manual Figure 9-2.A2 Current Amplifier PCAFigure 9-2.A2 Current Amplifier PCA cont Schematic DiagramsFigure 9-2.A2 Current Amplifier PCA cont 5725AInstruction Manual Figure 9-2.A2 Current Amplifier PCA cont Schematic Diagrams5725A-1661 5725AInstruction Manual Figure 9-3.A3 High Voltage Amplifier PCAFigure 9-3.A3 High Voltage Amplifier PCA cont Schematic DiagramsFigure 9-3.A3 High Voltage Amplifier PCA cont 5725AInstruction Manual aq59f.eps Schematic DiagramsFigure 9-4.A4 Power Supply PCA 5725A Figure 9-4.A4 Power Supply PCA contFigure 9-4.A4 Power Supply PCA cont Schematic DiagramsTYPICAL COMMUNICATIONS ACTIVITY AT PINS 12 AND 13 OF U5075725A Instruction ManualFigure 9-5.A5 Digital PCA cont Schematic DiagramsVOLTAGE STANDBY 5725AInstruction Manual STANDBYFigure 9-6.A6 High Voltage Sense PCA cont Schematic DiagramsFigure 9-6.A6 High Voltage Sense PCA cont 5725AInstruction Manual Figure 9-6.A6 High Voltage Sense PCA cont Schematic DiagramsFigure 9-6.A6 High Voltage Sense PCA cont 5725AInstruction Manual aq45f.eps Schematic DiagramsFigure 9-7.A12 Transformer Enclosure Assembly Instruction Manual 5725AIndex 5725A Page Instruction Manual 5725AManual Supplement rear Change #1