Fluke 35040 manual Theory Of Operation, Theory of Operation

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				Appendix	B
				Theory of Operation	B
	B.5 Theory Of Operation
	Basic Operating Equations

	Quantity	Description	Units	Comments

	QTimed	Timed Charge	C	The electrical charge delivered during the timer
				interval.
	QTimed_Predicted	Predicted	C	The total amount of timed charge that should be
		Timed Charge		accumulated at the completion of the timer
				interval, based on the observed delivery rate.

Leakage Measurements

Leakage measurements (QOffset, ILeakage and TOffset) are only applicable when automatic leakage compensation is enabled.

Timed Charge and Dose

This measurement accumulates charge only while the elapsed time is less than or equal to the timer interval setting. The displayed value is held following the completion of the timer interval.

QTimed = Q2[C] − Q1 [C] − (ILeakage [A] × (T 2 [s] − T 1 [s]))

DoseTimed = QTimed [C] × ICCF [Units/C] × ADCF

Q1 represents the next sample of charge at time T1 following the activation of the timer. Q2 corresponds to the interpolated charge at time T2, where T2 is an integral number of seconds that is restricted to times within the range: T1 < T2 ≤ (T1 + Timer Interval Setting).

Predicted Timed Charge and Dose

This measurement extrapolates the timed charge (QTimed) at the elapsed time (TElapsed) that should be accumulated at completion of the timer interval (i.e., TimerIntervalSetting) based on the rate of charge delivery.

= QTimed[C] ×

QTimed_Predicted TElapsed[s] TimerIntervalSetting[s]

DoseTimed_Predicted = QTimed_Predicted [C] × ICCF [Units/C] × ADCF

At the conclusion of the timer interval (i.e., TElapsed equals the TimerIntervalSetting), the predicted timed charge and dose are equal to the predicted timed charge and dose, respectively.

B-11

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Contents Therapy Dosimeter 35040Fluke Biomedical Table of Contents Troubleshooting and Service Addendum Features of Firmware Version 27JAN00 or LaterSample Customization Reports Iii Blank Features IntroductionIntroduction Before You Start Safety Precautions Safety Symbols And TermsOperators Manual Manual Addenda SpecificationsFactory Calibration Error Source ± %rdg Maximum ErrorCurrent Measurements Full Scale Range Display Resolution Noise ± countsFull Scale Range Display Resolution Timed Charge MeasurementsSpecifications Effective Exposure Time MeasurementsGeneral Measurements High Performance Power Supply and Battery Charger Unpacking and Inspection 35040 Functional Description Hardware Block Diagram of the Model 35040 Therapy DosimeterSerial Communications Port Power SupplyFront Panel MicroControllerMultiplexer and A/D Converter Basic Operating EquationsElectrometer Bias SupplyQAccumprevious Quantity Description Units CommentsQExposure QAccumCharge and Current Measurements Leakage Measurements= time of electrometer conversion s Timed Charge and Dose Exposure Charge and DoseExposure Current and Rate Setting ThresholdsPredicted Timed Charge and Dose Accumulated Charge and DoseDoseRate = I a × Iccf Units/C × Adcf × RateMultiplier s Exposure TimeAir Density Correction Factor ⎝ PMm Hg = inch Hg x Units Display Minimum Maximum Standard Resolution ErrorIntroduction SetupSetup Front Panel FamiliarizationRear Panel Familiarization Powering The SystemIon Chamber Connector Power-Up Self-Test and Display MessagesBasic Measurement Techniques General ConsiderationsMaking Non-Timed Exposure Measurements Timer Setup Timer Use3Making Timed Exposure Measurements Using Other Ion Chambers Battery CareFront Panel Controls PowerBattery Care Operation InstructionsPowering Up the Model 35040 Therapy Dosimeter Powering Down the Model 35040 Therapy Dosimeter Using the Test Function ButtonOperation Instructions QScaleFactor=1.0000 IScaleFactor=1.0000 5Automatic Leakage Compensation 12. The Test Function Screen Showing the Timer SettingsCalibrated by Keithley RMD Nov 15 17. The Test Function Screen Showing the Timer Settings 6Timer SetupUsing the AIR Density Button Using the Detector Select ButtonUsing the Bias Select Button Using the Units Select ButtonSet 300.0 V 100% Central Electrde Pos IC Bias 300.0 V CEP Overranging Conditions Using the RESET/MEASURE ButtonReset Error Overrange ConditionsCondition Values Overranged Annunciator Condition Reset Error With Automatic Leakage Compensation EnabledAnnunciators AnnunciatorsCondition Overranged Measurement Measurement Indicators and ConditionsIndicator Measurement Condition ? left of valueStarting the Customization Software Installing/Uninstalling Customization SoftwareCustomization Connection to the ComputerDownloading Menu Items and ControlsCOM Port Drop Down List Ion Chambers Close or File CloseFile Save AS and File Print Edit Special Items OK and Cancel36. The Special Items Menu Calibration Temperature has focus Download and CancelMeasurement Displays Display Line Operators Manual Available Display LinesChanging a Line on a Display Using the APPEND, DELETE, and Insert ButtonsDisplay Line Group Selection Selecting an Item and Placing It38. The Timer Intervals Form Timer Intervals39. The Bias Settings Form Bias SettingsExamples Deleting a Display Changing the Pressure UnitsCustomizing a Measurement Display Appending a DisplayErrors Troubleshooting Troubleshooting and ServiceSymptom LoBias annunciator displayed Symptom Display does not light up when Power is pressedSymptom ??Bias annunciator displayed Symptom HiBias annunciator displayedDo not make Symptom Internal Reset Error displayedSymptom Configuration Error displayed Bit Description ActionMeasurements. Return Symptom Current Overrange DisplayedSymptom Dashes displayed instead of digits Symptom Bias voltage measurement changes by one digitExample 299.9 to Display Will Not Light Hours? Is the battery voltage greater than 5.9 volts? Low BatteryBias Error Go toLine Model 35040 Therapy Dosimeter Fuse Replacement Line Fuse ReplacementInterface Connector Cleaning Cleaning The InstrumentReplaceable Parts Information Replaceable Parts Information Warranty InformationReplaceable Parts List Recalibration, Repair Information & Technical AssistanceBlank Sample Documents Sample Customization Reports35040 Appendix Sample Customization Reports 35040 Appendix Sample Customization Reports Blank Introduction New Features OverviewTimed Measurements Specifications Update New Features B SetupTimer Setup Procedure Timer Use ProcedureMaking Timed Exposure Measurements Setup B RESET/MEASUREAutomatic Leakage Compensation ADC ALCOperation Instructions B Start NA pA Stop Thres CurrentDecimal Places Timer SetupAnnunciators, Indicators, and Overrange Conditions Table B-2. Measurement Indicators and ConditionsTable B-1. Annunciators Condition Overranged Measurement1 Table B-3. Overrange ConditionsTheory of Operation Theory Of OperationConfiguration Error Service Required Error Number Main Menu Measurement MenuMeasurement Displays Figure B-9 shows the Measurement Displays dialog box Table B-4. Available Display Lines Figure B-10. The Timer Intervals dialog box Page Fluke Biomedical