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HP WaterSkis E1312A manual Noise Caused by Magnetic Loops, Noise Caused by Ground Loops

Models: WaterSkis E1412A WaterSkis E1312A

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Noise Caused by Magnetic Loops

If you are making measurements near magnetic fields, you should take the necessary precautions to avoid inducing voltages in the measurement conductors. You should be especially careful when working near conductors carrying large currents. Use twisted-pair connections to the multimeter to reduce the noise pickup loop area, or dress the input cables as close together as possible. Also, loose or vibrating input cables will induce error voltages. Make sure your input cables are tied down securely when operating near magnetic fields. Whenever possible, use magnetic shielding materials or physical separation to reduce problem magnetic field sources.

Noise Caused by Ground Loops

When measuring voltages in circuits where the multimeter and the device- under-test are both referenced to a common earth ground but at different points, a “ground loop” is formed. As shown below, any voltage difference between the two ground reference points (Vground) causes a current to flow through the measurement leads. This causes errors such as noise and offset voltage (usually power-line related), which are added to the measured voltage.

The best way to eliminate ground loops is to maintain the multimeter's input isolation from earth; do not connect the input terminals to ground. If the multimeter must be earth-referenced, be sure to connect it, and the device-under-test, to the same common ground point. This will reduce or eliminate any voltage difference between the devices. Also make sure the multimeter and device-under-test are connected to the same electrical outlet whenever possible.

28 HP E1312A/E1412A Multimeter Application Information

Chapter 2

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HP WaterSkis E1312A, WaterSkis E1412A manual Noise Caused by Magnetic Loops, Noise Caused by Ground Loops

Contents

Contents Frequency and Period Measurement Errors Zeroauto ZEROAUTO? IMMediate Chapter Multimeter Command Reference Appendix a Appendix B Contents HEWLETT-PACKARD Warranty Statement Documentation History Manufacturer’s Name July 31 Jim White, QA Manager Business Reply Mail Page HP E1312A and HP E1412A Multimeter Module Setup Using This ChapterSetting the Module Address Switch Interrupt Priority Setting the Line Frequency ReferenceChecking the Line Frequency Reference Page Switch Module Analog Bus Connections Multimeter Functional ConnectionsVoltage Measurement Connections Wire Ohms Measurement Connections HP E1312A and HP E1412A Multimeter Module Setup Chapter Initial OperationFunction Prototype HP E1312A and HP E1412A Multimeter Module Setup Chapter Measurement Tutorial Thermal EMF ErrorsDC Voltage Measurements Loading Errors dc volts Leakage Current Errors Thermoelectric VoltagesRejecting Power Line Noise Voltages Common Mode Rejection CMRNoise Caused by Magnetic Loops Noise Caused by Ground LoopsWire Ohms Measurements Resistance MeasurementsSet to 2-wire ohms function Errors in High Resistance Measurements Power Dissipation EffectsMaking High-Speed DC and Resistance Measurements DC Current Measurement Errors True RMS AC MeasurementsCrest Factor Errors non-sinusoidal inputs Common Crest Factors ExampleLoading Errors ac volts Temperature Coefficient ErrorsAC Measurements Below Full Scale Function and Range Change Internal Offset CorrectionLow-Level Measurement Errors Voltage Measured = Vin2+ Noise2Frequency and Period Measurement Errors AC Current Measurement ErrorsMaking High-Speed AC Voltage or Current Measurements Measurement Configuration AC Signal Filter DC Input ResistanceNumber of Power Line Cycles Nplc Resolution Chapter HP E1312A/E1412A Multimeter Application Information SENSeZEROAUTO Offonceon Math Operations CALCulate Subsystem Null Relative FunctionDB Measurements CONFfunctionStoring the dB Reference Value DBm MeasurementsStoring the dBm Reference Resistance Value HP E1312A/E1412A Multimeter Application Information Chapter Triggering the Multimeter TRIGgerSOURce EXTernal Checking the Trigger Source Bus Triggering Wait-for-Trigger StateExample Setting the Trigger Count Checking the Trigger Count Inserting a Trigger DelayExample Inserting a Trigger Delay Default Trigger Delays Example Setting the Sample Count Querying Delay Time Sample CountChecking the Sample Count HP E1312A and HP E1412A Multimeter Application Examples HP VTL Software VisaMEASure Command Making Multimeter MeasurementsMEASURE1 Source Code File MEASURE2 Source Code FileMEASURE3 Source Code File InitMEASURE4 Source Code File Synchronizing Multimeter With a Switch Module HP E1412A Multimeter and Switch Module SynchronizationSee -5 for the HP E1312A/E1412A Multimeter status system Set up the Multimeter Now set up the switch moduleCheck the multimeter for system errors Retrieve the readings from the multimeterMultimeter Status System Examples Synchopc Source Code File RST CLS *ESE Init OPCSynchmav Source Code File RST Init FETC?Limittst Source Code File End Loop Check the multimeter for system errorsLoop Device Configuration Programming ExamplePage HP E1312A/E1412A Multimeter Application Information Chapter Common Command Format Command TypesCommand Format Abbreviated Commands Implied Commands CommandSeparator Linking Commands ParametersMultimeter Range and Resolution Tables PLCAC Voltage Range versus Resolution Scpi Command ReferenceAC Current Range versus Resolution ABORt Related Commands INITiate, TRIGgerAborting a Measurement Subsystem Syntax CALCulateValid Math/Measurement Function Combinations AVERageAVERage? AVERageCOUNt?AVERageMAXimum? AVERageMINimum?DBREFerence DBREFerence?DBMREFerence DBMREFerence?FUNCtion FUNCtion?Parameter Summary Example Example Query the Calculate Math FunctionLIMitLOWer LIMitLOWer?LIMitUPPer LIMitUPPer?NULLOFFSet NULLOFFSet?STATe STATe?CALibration COUNt?LFRequency CommentsExample Query the Line Frequency Setting LFRequency?SECureCODE Example Enter a New Calibration Security CodeSECureSTATe SECureSTATe?STRing Example Set the Calibration State to UnsecuredSTRing? VALueVALue? Example Query the Calibration MessageZeroauto CALibration? CAL?CONFigure Command SettingDefault Settings for CONFigure Command by Function Function Range ResolutionCURRentAC Example Making AC Current MeasurementsCURRentDC Example Making DC Current MeasurementsResolutionMINMAXDEF selects the frequency function Example Making 4-Wire Ohms Measurements FRESistancePERiod Resolution Minmaxdef Example Making 2-Wire Ohms MeasurementsVOLTageAC Example Making AC Voltage MeasurementsVOLTageDC Example Making DC Voltage MeasurementsVOLTageDCRATio Sense HI and LO inputCONFigure? String ReturnedData POINts?FETCh? Example Transferring Stored Readings to Output BufferIMMediate INITiateExample Placing Multimeter in Wait-For-Trigger State Example Query the Input Impedance Mode INPutIMPedanceAUTO IMPedanceAUTO?MEASure CURRentAC? MEASCURRAC? 1,MAXCURRentDC? MEASCURRDC? .1,MAXFREQuency? FRESistance? MEASFRES? 1500,MAXPERiod? RESistance? VOLTageAC? VOLTageDC? VOLTageDCRATio? Example Making DC Voltage Ratio MeasurementsTTLTrgSTATe OUTPutRST Condition OUTPTTLTn OFF Example Route Voltmeter Complete to Trigger Line TTLTrgSTATe?Example Query Voltmeter Complete Destination READ? Example Transfer Readings Directly to Output BufferCOUNt SAMPleRST Condition Sampcoun Example Set the Sample Count Example Query the Sample Count SAMPCOUN?SENSe Zero Auto Offonceon AUTO? Example Query the Measurement Function FunctionCURRentACRANGe? CURRentACRANGeExample Query the AC Current Measurement Range Example Disable AC Current Autoranging Example Query the AC Current Autorange ModeCURRentACRANGeAUTO CURRentACRANGeAUTO?CURRentACRESolution CURRentACRESolution?CURRentDCAPERture CURRentDCAPERture?Example Set an Aperture Time of 16.7ms Example Query the Aperture TimeCURRentDCNPLC? CURRentDCNPLCExample Query the DC Current Integration Time CURRentDCRANGe CURRentDCRANGe?Example Set the DC Current Range to 3A Example Query the DC Current Measurement RangeExample Disable DC Current Autoranging Example Query the DC Current Autorange ModeCURRentDCRANGeAUTO CURRentDCRANGeAUTO?CURRentDCRESolution CURRentDCRESolution?DETectorBANDwidth DETectorBANDwidth? FREQuencyAPERtureFREQuencyAPERture? Example Query the Detector BandwidthFREQuencyVOLTageRANGe FREQuencyVOLTageRANGe?Example Set the Voltage Range for Frequency Measurements to Example Query the Measurement RangeExample Disable Autoranging Example Query the Autorange ModeFREQuencyVOLTageRANGeAUTO FREQuencyVOLTageRANGeAUTO?FRESistanceAPERture FRESistanceAPERture?FRESistanceNPLC? FRESistanceNPLCExample Query the Integration Time FRESistanceRANGe FRESistanceRANGe?FRESistanceRANGeAUTO FRESistanceRANGeAUTO?FRESistanceRESolution FRESistanceRESolution?Example Query the Resolution RST Condition Fresres 1mΩ 1E-03PERiodAPERture? PERiodAPERtureRST Condition 0.1 100ms Example Set the Aperture Time PERiodVOLTageRANGe PERiodVOLTageRANGe?Example Set the Voltage Range for Period Measurements to Example Query the Period Voltage RangePERiodVOLTageRANGeAUTO PERiodVOLTageRANGeAUTO?RESistanceAPERture RESistanceAPERture?RESistanceNPLC RESistanceNPLC?RESistanceRANGe? RESistanceRANGeRST Condition Resrang 1kΩ Example Change the Range RESistanceRANGeAUTO RESistanceRANGeAUTO?RESistanceRESolution? RESistanceRESolutionExample Change the Resolution VOLTageACRANGe VOLTageACRANGe?VOLTageACRANGeAUTO Example Disable AC Voltage AutorangingVOLTageACRANGeAUTO? VOLTageACRESolution? VOLTageACRESolutionRST Condition 1E-04 Example Change the Resolution VOLTageDCAPERture VOLTageDCAPERture?VOLTageDCNPLC VOLTageDCNPLC?VOLTageDCRANGe VOLTageDCRANGe?VOLTageDCRANGeAUTO VOLTageDCRANGeAUTO?VOLTageDCRESolution VOLTageDCRESolution?Example Disable Autozero Example Query the Autozero ModePRESet QUEStionableENABleSTATus QUEStionableCONDition?QUEStionableENABle? QUEStionableEVENt?ERRor? Example Reading the Error QueueSYSTem VERSion?TRIGger RST Condition Trigcoun Example Set the Trigger CountExample Set the Trigger Delay DELayExample Query the Trigger Count DELay? DELayAUTOExample Query the Trigger Delay Example Disable Automatic Trigger DelayDELayAUTO? Example Query the Trigger Delay ModeSOURce Related Commands INITiate, READ?, MEAS?Example Set the Sample Source SOURce? Example Query the Trigger SourceIeee 488.2 Common Command Quick Reference Category Command Title DescriptionExample Enable All Error Events ESE and *ESE?ESR? SRE and *SRE? RST does not affectSTB? Scpi Command Quick Reference HP E1412A C-size 6½-Digit MultimetersData 67sMINMAX Zeroauto Offonceon HP E1312A and HP E1412A Multimeter Specifications DC CharacteristicsMeasuring Characteristics 60 Hz 50 HzOperating Characteristics AC Characteristics True RMS ACTrue RMS AC Voltage System Speeds 10 Frequency and Period Characteristics Accuracy Specifications ±% of reading 1Configuration Rates 14/sec Autorange Time General Specifications To Calculate Total Measurement Error Understanding the % of reading ErrorTotal Measurement Error Interpreting Multimeter Specifications Number of Digits and OverrangeAccuracy Configuring for High Accuracy Measurements DC Voltage, DC Current, and Resistance MeasurementsExecution Errors 112Program mnemonic too long 113Undefined header121Invalid character in number 123Numeric overflowTo -168Block data errors To -178Expression errors221Settings conflict 211Trigger ignored330Self-test failed 350Too many errors440Query Unterminated after indefinite response Cannot achieve requested resolution Cannot use overload as math referenceCal signal measurement out of range Cal signal frequency out of rangeCal secured Invalid secure codeNo cal for this function or range HP E1312A and HP E1412A Multimeter Error Messages Appendix B Measurement Speed and Accuracy Trade-offs Measurement Speed and Accuracy Trade-offs Appendix C HP E1312A/E1412 Special Function General Guidelines for Increasing Measurement Speed Minimize Number Command Response SessionsAvoid Function Changes Avoid Aperture Changes Set Autozero to Once or OFF Turn Autorange Decrease Aperture Time or NPLCsSetting the Resolution INITFETCH?Index 197 Index 124 Index Index Error, 180 See online help Cycles, 27, 38, 123, 132, 140 Errors 130 Setting resolution, 15, 38 160 Index