INFOCAL 5 handbook - MPIPinfos.mpip.free.fr/siemens/Debit/A ultrason/Sitrans... · Insert floppy diskette # 1 into the diskette drive. Use "Start", "Run"- browse to C:\temporary and

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Manual

INFOCAL 5 Energy calculator

Verification equipmentSoftware version 1.00

[ ]

*085R9446*SAP No. 521H1089DKFD.PS.022.H2.02

Flow Division

FLOW DIVISION - SIMPLY BETTER

Danfoss Flow Division

operating under

Siemens Flow Instruments A/S

as of September 1, 2003

INFOCAL 5 Verificator

2 DKFD.PS.022.H2.02

Contents 1. Introduction ................................................................................................................... 3

2. PC requirements ........................................................................................................... 3

3. Software installation ..................................................................................................... 3

4. Function ......................................................................................................................... 44.1 Verification according to EN 1434 ................................................................................. 44.2 Verification with connected temperature sensors or decade boxes ........................... 4

5. Connecting INFOCAL 5 test equipment to the PC ..................................................... 4

6. Using the software program ........................................................................................ 56.1. Verification data .............................................................................................................. 56.1.1 Choose certificate template ........................................................................................... 56.1.2 Test points ...................................................................................................................... 66.1.3 Verification ...................................................................................................................... 66.1.4 Heat coefficients ............................................................................................................. 66.2. Passwords ...................................................................................................................... 66.3. Change of parameters under "Verification data" ........................................................... 76.4. Verification ...................................................................................................................... 76.5. Test data ......................................................................................................................... 86.6. Storing of data ................................................................................................................ 86.7 Certificate ....................................................................................................................... 8

7. Calibration routine ........................................................................................................ 9

8. Integration time (measuring time) ............................................................................. 11

9. Calculation of measurement uncertainty ................................................................ 119.1 Assumptions for the calculation ................................................................................... 12

Uncertainty calculation for test point T1 ....................................................................... 13Uncertainty calculation for test point T2 ....................................................................... 14Uncertainty calculation for test point T3 ....................................................................... 15

10. Possible improve- ments/adjustments of the measurement uncertainty ............. 15


3DKFD.PS.022.H2.02

1. Introduction The verfication equipment is used to test and verify the INFOCAL 5 energy calculator based onvolume and high precision resistors simulating temperature values.

The verification equipment offers you either a verification of the INFOCAL 5 itself or if requireda verification of INFOCAL 5 with temperature sensors in a temperature controlled bath.Alternatively external resistor-decade boxes may be used.

Verification equipment consists of a base part with simulation resistors, relays, a micro controller,net-adapter with 12 V AC, D-sub cable and diskettes with PC software.The calibration sequence is being controlled from the PC.

The equipment is primarily designed for use in laboratories testing and verifying heat meters.It can also be used simply to test if the INFOCAL 5 is functional.

Finally after verification a test certificate can be printed out and results stored.

Template certificate language can be changed into local language.

2. PC requirements The PC must be an IBM compatible 486 or Pentium, with at least 8 MB RAM.To install the program at least 10 MB must be available on the hard disk, the PC must be equippedwith a 3,5"/1.44 MB floppy drive.The program must be installed on the hard disk. Do not run the program directly from the floppydiskettes.

The program will run under Windows WIN 95 or Win 98 and requires Excel program to be installed.

The monitor has to be VGA as the programme is displayed in a VGA format.If the monitor has a better resolution than VGA, the menu displayed will be more compact andnot fill the entire screen.COM port 1 or COM port 2 must be available for interface to the test equipment.The software programme can be set either to COM 1 or COM 2.

1. Introduction

3. Software installation Check that the computer has at least 10 MB of space available on the hard disk.

Carefully study the read-me file before starting the installation.

Do not install directly from disc. For correct installation, copy disc to a temporary directory on yourlocal driver.

Close any other programs you have opened under windows before installing the programme.

Insert floppy diskette # 1 into the diskette drive.

Use "Start ", "Run "- browse to C:\temporary and select "setup.exe" .

Follow the directions given by the program, insert diskette #2 when promted to do so.

When installation is completed, an icon will appear on your monitor.The INFOCAL 5 Verificator can now be started from the program files.


4 DKFD.PS.022.H2.02

Verification is carried out as the equipment simulates 3 sets of forward and return temperaturegiving three test points: T1, T2 and T3.

The test point is selected according to the test point required in EN 1434 which are:Selected value: EN 1434 requirements:1. 3,5°K DQmin. < DQ < 1.2 x DQmin.2. 19°K 10K < DQ < 20K3. 145°K DQmax. –5K < DQ < DQmax.

The test equipment contains precision resistors, which simulate the above forward and returntemperatures.The resistor sets are connected to the INFOCAL 5 by use of high quality relays with double platedgold contacts sets. The design ensures minimum influence of the contact resistance on the testresults.

At delivery the actual resistor values are measured with a calibrated, traceable highaccuracy instrument and entered into the E-prom in the verification unit.

Even though the resistors are very stable, they must be re-calibrated on a regular basis tocompensate for any drift in resistance. Preferably the calibration shall be performed underenvironmental conditions (room temperature) close to those under which the equipment lateris operated.If the measured resistor-values differ from the preset values, the new values must be entered intoin the program.

The equipment simulates a water volume with a pulse frequency of 100 Hz generated in the microcontroller.According to the preset integration time (test time for test point T1, T2, T3) in the program, a volumeis simulated into the INFOCAL 5.

ExampleA INFOCAL 5 with 25 pulses/litre is tested on the verfication equipment.Integration time for T1 is set to 30 sec.30 x 100 Hz = 3000 pulses3000 pulses/25 imp/l = 120 litresThe simulated "true" energy is calculated by the equipment as a function of the simulatedtemperature difference, the simulated water volume and the simulated temperature with respectto forward/return installation of the flow meter according to tables of heat coefficient from Dr.Stuck*).The software contains an automatic calculation of heat coefficient values, alternatively the heatcoefficient values can be entered manually according to local requirements.The "true" energy is related to the measured energy by the INFOCAL 5.The measurement error (accuracy) of the INFOCAL 5 at the test point can then be calculated andpresented in percentage of the true value.The measurement error presented in percentage in three different test points, T1, T2 and T3.Based on the "measurement error" and the dedicated MPE – values (Maximum Permissible Error)eventually reduced with the measurement uncertainty, the software decides if the heat meterkeeps its verifications tolerances. A green or red flashing information field completes theverification.*) Tabels and coefficient for water and heat-conveying liquid.

ã1986 by Wirtschaftverlag NW, ISBN 3-88314-522-X.

4. Function

4.1 Verification accordingto EN 1434

Alternatively to the procedure stated in "4.1" the verification equipment can be used for otherverification modes, e.g. OIML R 75 where it is allowed to verify energy calculators includingsensor pair or as separate units at other test points than those stated in EN 1434.The software offers the possibility to stop the verification routine temporarily in order to move thetemperature sensors from one bath to another or change resistor values on the decade boxesrepresenting the forward and return temperatures.In this situation the wires in terminal 5 - 6 and 7 - 8 have to be disconnected from the internalresistors on the printed circuit board and replaced with the wires from the forward and returnsensors or with wires to the decade boxes representing forward/return temperature.

4.2 Verification withconnected tempera-ture sensors ordecade boxes

The 9 terminal D-Sub connector and the net-adapter must be connected and switched "On"before running the program.The 9 terminal D-sub connector must be connected to one of the COM ports of the PC.If COM port 2 is chosen remember to set COM port 2 active in the INFOCAL 5 verification program.

The net-adapter is a 230 V AC to 12 V AC adapter.

5. Connecting INFOCAL 5test equipment to thePC


5DKFD.PS.022.H2.02

Remove the top cover and mount an INFOCAL 5 in the base part. (Device under test).

Start the INFOCAL 5 calibration/verification programme from the start menu or a shortcut on thedashboard.The program will automatically open the folder "Verification data " and a dialog box will appear.

NoteThe dialog box only appears first time the programme is running. To open dialog box write"Setup" under folder "Verification data" .

6. Using the softwareprogram

6.1. Verification data

In order to verify INFOCAL 5 by use of internal reference resistors representing DQ = 3,5K,DQ = 19K and DQ = 145K click "OK" or make selection.

The program is default set to:

Test points: Resistor basedVerification at T1, T2, T3: No stopsHeat Coefficients: Auto calculate

Language select: English or Polish.

Create a directory for your certificates. Choose e.g. C:\CERTIFICATES or any other name youmay find convenient. Even using a network drive is possible. Copy the the Excel file CerTemplate.xlsfrom disc 4 to your certificate directory. This file is your certificate template (the empty certificate).CerTemplate.xls is in English, but can be modified to any language by any Excel user.

To modify the template open the CerTemplate as read only. Save the new template underanother file name with the extension “.xls” .

Open the file for modification by inserting the password “danfoss” under tools - protection -unprotect sheet or similar dependent on the Excel version you are using.

Point to the text you want to change into your local language. To change into a local font selectthe field you want to change and then open format - cell - font and choose the desired font.

Having finished the modification, open tools - protection - protect sheet and insert yourpassword for protection of the template.

Save the template.

6.1.1 Choose certificatetemplate


6 DKFD.PS.022.H2.02

6.1.2 Test points Resistor basedUses the internal reference resistors in the verification equipment.The reference resistor values can be measured with a high accuracy ohmmeter and entered inthe software programme. The program automatically converts the resistor values into thecorresponding temperatures according to IEC751.Resistor based principle is also used when forward and return temperatures are simulated withdecade boxes. In this situation the wires from the decade boxes must be connected to theterminals 5 - 6 and 7 - 8 after disconnecting the wires for the internal resistors.

NoteThe resistors are measured at Danfoss in Denmark with traceability to the Danish nationalstandards for electrical, resistance.

For some countries verification is only valid when the equipment used is traceable to thenational standards of this country. In this case the resistors must be calibrated locally with therequired traceability.

Temperature basedThis mode is used when verification of the energy calculator including temperature sensors isrequired. For this purpose a temperature difference must be established by means of twotemperature controlled, well stirred liquid baths.

The reference temperature measured in °C for forward/return by a thermometer (workingreference).The deviation in read values and true temperature (measured by the laboratory reference).Thermometer can be entered with sign.From the factory the deviation value is set default to 0 °C for T1, T2 and T3.

6.1.3 Verification No stopsTest are carried out without any stop between the test points T1, T2 and T3.

Intermediate stopsTest are carried out at the 3 test points. This allows time for changing the set points of tempera-ture baths and temperature stabilization or changing the setting of the decade resistor boxessimulating the return and forward temperature. After stabilizing the forward and return tempera-tures measured by the working reference, these temperatures must be entered into the folder"verification".A stabilization time in the baths, can be entered in order to temperature stabilize the sensor beforemeasuring.A dialog box appears when the sensors can be moved to the next bath.

6.1.4 Heat coefficients Auto calculateThe heat coefficients are automatically calculated depending on the true temperature in forwardand return for T1, T2 and T3.

The calculation is based on the algoritm found in the "Tabels and coefficient for water as heat-conveying liquid. ã 1986 by Wirtschaftverlag NW, ISBN 3-88314-522-X"

Manual insertThe heat coefficients can be entered manually based on local recommendation.Whenever changing heat coefficient manually, a password must be entered.

6.2. Passwords In order to change any verification data, a password must be entered - followed by an "Apply "in the PC software.

Following passwords have been default selected:

Change of modes for test points, heat coefficients and verification: Write "Setup " under thewindow "Verification data ".

Change of verifications data: Write "danfoss ".


7DKFD.PS.022.H2.02

6.3. Change ofparameters under"Verification data"

Before change of preset values for heat coefficients, integration time and permissible errors, apassword must be entered.

Integration time is preset from Danfoss and effect the uncertainty of the calibration/verfication.

Danfoss recommend the following preset values:

3°K < DQ £ 10K: Minimum 30 sec.10°K < DQ £ 15K: Minimum 10 sec.15°K < DQ: Minimum 5 sec.

The influence of integration time can be studied in details in chapter: "Calculation of measurementuncertainty".

6.4. Verification After having checked the folder: "Verification data " is correct, - switch to the folder "Verification ".

In the folder "Verification " all data referring to the INFOCAL 5 (device under test) can be entered.

a Type: Build-up number of the unit.

b Serial No.: Enter the serial number of INFOCAL 5.

c Identify field: Possibility for customer name, calibration operator and approved signatory.

d Comment field: Ex with metrological data, room temperature, humidity, pressure,instrument data, reference manuals etc.

The INFOCAL 5 is now ready for calibration/verification.

Start the verification by entering "Start verification ".A progress line indicates the status of the program.

NoteIf selected verification "one at the time" a dialog box will appear indication when it is time tomove the forward sensors to the next temperature bath or change the resistor value in thedecade boxes.


8 DKFD.PS.022.H2.02

When the test have been completed, the results will be displayed on the screen and followed bya message "INFOCAL 5 accepted " or "INFOCAL 5 not accepted ", based on the limits MPE(Maximal Permissible Errors).

6.5. Test data

If the verification is accepted (lower than MPE values) the data can be stored by a click on "File "and then "Save verification file ".The file can be retrieved by "Open verification file ".

6.6. Storing of data

Results of verification can be printed by a click on the botton: "certificate ".6.7 Certificate

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T1 53.395 49.997 4.1309 0.12 0.00047 0.00047 -0.523 1.36T2 68.88 49.997 4.1341 0.04 0.00087 0.00087 -0.193 0.66T3 159.837 15.011 4.2173 0.02 0.00339 0.00339 -0.018 0.5

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Verified by: _____________ Date: ___________ Approved signatory: _____________

.../continued


9DKFD.PS.022.H2.02

ImportantIf the base part contains a 230 V AC supply or 24 V AC supply, it is important to wait min. 20sec. or until the display segments have disappeared in the display, before connecting top andbase part!

For battery versions, connections of top and base part can take place without any waiting time.

The verification equipment has very long-term stable resistance references.Under normal conditions these require just calibration once a year or whenever moving the verifi-cation equipment to another locality.

During calibration use an accurate precision ohmmeter with 4 wire measuring principle andtraceable calibration .

Before starting calibration routine disconnect the cable to the COM port in the PC and brieflydisconnect the 230 V supply in order to reset activated relays on the printed circuit board.

1. Turn on the power to the verification equipment.Disconnect the red wires from terminal 5 & 6 and the blue wires from terminal 7 & 8.

7. Calibration routine

The cable to the computer has the following colours: TX: yellow, RX: green, GND: white.12 V power terminal requires 12 V AC and have no polarisation.

Verfication mode: off onJumper:

Jumper J4

Jumper J3

Jumper J2

Jumper J1

12 V AC

Flow pulse wire to

terminal 10

3 wire cable to PC


10 DKFD.PS.022.H2.02

2. Connect the red wires (5 & 6) to the calibration ohmmeter.Move jumper J1 to the "On" position. Relay RL 1 is active.Make a note of the measured T1forward (approx. 603 ohm).Connect the blue (7 & 8) wires to the calibration ohmmeter.Make a note of the measured T1return (approx. 597 ohm).Move jumper J1 back in position.

3. Connect the red wires (5 & 6) to the calibration ohmmeter.Move jumper J2 to the "On" position . Relay RL 2 is active.Make a note of the measured T2forward (approx. 633 ohm).Connect the blue (7 & 8) wires to the calibration ohmmeter.Make a note of the measured T2return (approx. 597 ohm).Move jumper J2 back in position.

4. Connect the red wires (5 & 6) to the calibration ohmmeter.Move jumper J4 to the "On" position. Relay RL 4 is active.Make a note of the measured T3forward (approx. 805 ohm).Connect the blue (7 & 8) wires to the calibration ohmmeter.Make a note of the measured T3return (approx. 529 ohm).Move jumper J4 back in position.

5. Make sure that all the four jumpers are in the "Off " position.

After the new resistance values and heat coefficients are entered "Apply " must be entered.

NoteIf the mode "automatic calculation" in setup mode is chosen, the heat coefficients areautomatically updated.

The verification equipment is now ready for use.

The three values for Tf and the three values for Tr are automatically generated based on thefollowing formula:

RT = R0 (1 + A x T + B x T2)

R0 = resistance at 0 °C, Pt 500: = 500 WA = 0.0039083 °C-1

B = -0.5775 x 10-6 °C-2

T can be calculated from the resistance as follows:

The above relations are according to IEC751.

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11DKFD.PS.022.H2.02

8. Integration time(measuring time)

As the INFOCAL 5 is placed in the basepart, the INFOCAL 5 is automatically set into a verificationmode and the "heart beat " indicator on the display indicates that the INFOCAL 5 now is in theverification mode. The INFOCAL 5 now integrates every second.

This means that the INFOCAL 5 will measure the forward and return temperatures, the volumepulses and increase the accumulated energy value every second.

As the integration time influences the variance of the accumulated energy in a test point, we mustconsider this in the selection of integration time at the different test points. Further more the naturalrepeatability is better with high temperature differences. These considerations are explainedmore in details in the paragraph "Calculation of measurement uncertainty".

As default Danfoss have the factory settings:Integration timeT1: 30 sec.T2: 10 sec.T3: 5 sec.

and Danfoss recommend not to change these setting as it will affect the measuring stability.

These integration result in the overall measurement uncertainty of:T1 = 0,63%T2 = 0,17%T3 = 0,039%

See the next chapter for detailed description.

9. Calculation ofmeasurementuncertainty

The calculation below of the measurement uncertainty of the equipment partly depends on thefrequency with which the equipment is calibrated. The calculation therefore is only intended asa guide.

The calculations are based on EAL-R2, April 1997, "Expression of the Uncertainty of measure-ment in Calibrations" and GUM "Guide to expression of Uncertainties in Measurements". Tocalculate the best measurement capability, you must calculate the uncertainty for each of theuncertainty components as a standard deviation before adding them up according to the rulesof adding up standard deviations for normal distribution/Gaussian distribution.

If the distribution of the uncertainty component is not the normal distribution/Gaussian distribu-tion, the standard deviation must be calculated on the basis of your knowledge of the distributiontype as well as upper and lower limit +a, -a (e.g. factory specifications and experience notoriousvalues). Especially for the rectangular distribution used in this case, the standard uncertainty iscalculated as a/Ö3.

Step by step guide· Calculate the standard deviation for each uncertainty component.· Square to convert to (statistical) variance.· Simply add up to find the total variance.· Calculate the 1-sigma measurement uncertainty as the square root of the total variance.· Multiply by 2 (coverage factor k = 2) to calculate the best measurement capability.

To this you must add the measurement uncertainty from the calibration of the referenceresistances.

Finally, to reach the total measurement uncertainty, you have to add the natural variance of theenergy calculator readout at each test point.


12 DKFD.PS.022.H2.02

9.1 Assumptions for thecalculation

The basis of the calculation is the energy calculation formula:

whereE = energyV = volumeDQ = temperature difference Tforward - TreturnkStuck = heat coefficient

To ascertain the uncertainty of the simulated energy, E, you have to determine the uncertainty(standard deviation) of each element on the right side in the formula.

Volume, V, has the uncertainty 0 as the energy calculator is always stimulated by a precisenumber of (volume) pulses.

The temperature difference, DQ, is influenced by the uncertainty of the two resistances simulatingforward and return temperatures. These are influenced by variations in ambient temperature, thestability of the resistances and the calibration.

The heat coefficient, kStuck , is associated with no uncertainty.

In other words, only the uncertainty of the resistances determines the best measurementcapability of the simulated energy, E.

The resistances (Wishay S102C) have the following characteristics:

Temperature coefficient: ±1.2 ppm/°KStability: ±25 ppm/year

The calibration of the resistances only contributes with the short-term stability and the linearityof the reference ohmmeter. The absolute accuracy is not that important as it does not contributeto any measurement uncertainty for the temperature difference, DQ, simulated by Tforward andTreturn. The estimated effect per resistance is approx. 4 ppm.

The equipment is expected to be calibrated with an uncertainty ±10 ppm at 23 °C ±1 °C at leastonce a year.

Expected ambient temperature is 23 °C ±5 °C when using the verification equipment.

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13DKFD.PS.022.H2.02

Tforward = 53.5 °C corresponding to Rforward = 603.721 WTreturn = 50 °C corresponding to Rreturn = 596.986 WDQ = 3.5K

TreturnTemp. 596.986 W x 1.2 x 10-6/K x 5 °C/Ö3 = 2.1 mW ~ 0,0011K s2 = 1.21 x 10-6 [K2]Stab. 596.986 W x 25 ppm/year x 1 year/Ö3 = 8.6 mW ~ 0,0045K s2 = 20.3 x 10-6 [K2]TforwardTemp. 603.721 W x 1.2 x 10-6/K x 5 °C/Ö3 = 2.1 mW ~ 0,0011K s2 = 1.21 x 10-6 [K2]Stab. 603.721 W x 25 ppm/year x 1 year/Ö3 = 8.7 mW ~ 0,0045K s2 = 20.3 x 10-6 [K2]Calibration 2 x 600 W x 4 x 10-6/Ö3 = 2.8 mW ~ 0.0014K s2 = 1.96 x 10-6 [K2]

Ss2 = 45.0 x 10-6 [K2]Measuring uncertainty of 1 x std. dev. level s = 0.0067 [K]Best measurement capability 0.0134 [K ](expanded measurement uncertainty, k = 2)

The best relative measurement capability at DQ = 3K thus is 0.0134/3 x 100% = 0.45%

The best measurement capability expresses the measurement uncertainty of the verificationequipment at T1. To this you will have to add the measuring uncertainty of the energy calculatori.e. the repeatability to obtain the total measurement uncertainty of the calibration at T1.

Tests have shown that the INFOCAL 5 has a repeatability of 1.21% on single measurements ofDQ. If at T1 the verification includes n temperature integrations, the accumulated energy will bedistributed with a repeatability of 1.21%/Ön.If at T1 30 integrations are selected, the energy calculator will contribute with 1.21%/Ö30 = 0.22%.

The combined measuring uncertainty thus is:

%63.0%)22.02(%)45.0( 22 =×+=8 (k = 2)

Uncertainty calculation fortest point T1


14 DKFD.PS.022.H2.02

Tforward = 69 °C corresponding to Rforward = 633.462 WTreturn = 50 °C corresponding to Rreturn = 596.986 WDQ = 19K

TreturnTemp. 596.986 W x 1.2 x10-6/K x 5 °C/Ö3 = 2.1 mW ~ 0.0011K s2 = 1.21 x 10-6 [K2]Stab. 596.986 W x 25 ppm/year x 1year/Ö3 = 8.6 mW ~ 0.0045K s2 = 20.3 x 10-6 [K2]TforwardTemp. 633.462 W x 1.2 x 10-6/K x 5 °C/Ö3 = 2.2 mW ~ 0.0011K s2 = 1.21 x 10-6 [K2]Stab. 633.462 W x 25 ppm/year x 1year/Ö3 = 9.2 mW ~ 0.0048K s2 = 23.0 x 10-6 [K2]Calibration (597 W + 633 W) x 4 x 10-6 /Ö3 = 2.8 mW ~ 0.0014K s2 = 1.96 x 10-6 [K2]

Ss2 = 47.7 x 10-6 [K2]Measuring uncertainty of 1 x std.dev. level s = 0.0069 [K]Best measurement capability 0.0138 [K ](expanded measurement uncertainty, k = 2)

The best relative measurement capability at DQ = 19K thus is 0.0138/19 x 100% = 0.072%




%17.0%)076.02(%)072.0( 22 =×+=8 (k = 2)



15DKFD.PS.022.H2.02

Tforward = 160 °C corresponding to Rforward = 805.272 WTreturn = 15 °C corresponding to Rreturn = 529.247 WDQ = 145K

TreturnTemp. 529.247 W x 1.2 x 10-6/K x 5°C/Ö3 = 1.8 mW ~ 0.0010K s2 = 0.91 x 10-6 [K2]Stab. 529.247 W x 25 ppm/year x 1year/Ö3 = 7.6 mW ~ 0.0040K s2 = 15.8 x 10-6 [K2]TforwardTemp. 805.272 W x 1.2 x 10-6/K x 5°C/Ö3 = 2.8 mW ~ 0.0015K s2 = 2.10 x 10-6 [K2]Stab. 805.272 W x 25 ppm/year x 1 year/Ö3 = 11.6 mW ~ 0.0060K s2 = 36.5 x 10-6 [K2]Calibration (529 W + 805 W) x 4 x 10-6/Ö3 = 3.1 mW ~ 0.0016K s2 = 2.57 x 10-6 [K2]

Ss2 = 57.9 x 10-6 [K2]Measuring uncertainty of 1 x std. dev. level s = 0.0076 [K]Best measurement capability 0.0152 [K ](expanded measurement uncertainty, k = 2)

The relative measuring ability at DQ = 145K thus is 0.0152/145 x 100% = 0.010%




(k = 2)%039.0%)018.02(%)0152.0( 22 =×+=8

The stability of the resistances contributes most to the measurement uncertainty. A more frequentcalibration will reduce the drift between two calibrations and thus also reduce this component.

From experience we know that the stability will be even better than specified by Wishay. After aperiod of 1 - 2 years the stability typically will be 10 - 15 ppm/year.

When experience with the stability of resistances is obtained, it can be incorporated in theuncertainty calculation thus contributing to a smaller measurement uncertainty.

Also when increasing the number of integrations the measurement uncertainty can be reduced.An increased number of integrations, however, means a longer verification time.

As a rule-of-thumb you must choose the number of integrations so that the uncertainty contributedby the energy calculator equals the best measurement capability of the verification equipmentat the test point.

10. Possible improve-ments/adjustments ofthe measurementuncertainty


ã Danfoss A/S (FD-SJ/KN/SSS&GBIN/KH) 06.2001 P65DKFD.PS.022.H2.02521H1089

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Documents

INFOCAL 5 handbook - MPIPinfos.mpip.free.fr/siemens/Debit/A ultrason/Sitrans... · Insert floppy diskette # 1 into the diskette drive. Use "Start", "Run"- browse to C:\temporary and