SIM.EM – S10
RMO COMPARISON FINAL REPORT High value resistance comparison with twoterminal cryogenic current comparators
Marcos E. Bierzychudek,
Instituto Nacional de Tecnología Industrial, Argentina.
Randolph Elmquist,
National Institute of Standards and Technology, U.S.A.
Felipe Hernández,
Centro Nacional de Metrología, México.
Aug, 2013 Buenos Aires, Argentina
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1. INTRODUCTION..............................................................................................................................3 2. PARTICIPATING LABORATORIES ..............................................................................................3 3. TRAVELING STANDARDS .............................................................................................................3 4. DESCRIPTION OF THE TRANSPORT PACKAGE ......................................................................4 5. MEASUREMENT PROCEDURES AND INSTRUCTION.............................................................4 6. MEASUREMENT RESULTS ...........................................................................................................4
1 MΩ STANDARD – SN: 8409005 .............................................................................................................5 1 MΩ STANDARD – SN: 8409007 .............................................................................................................5 10 MΩ STANDARD – SN: 1100955 ...........................................................................................................6 10 MΩ STANDARD – SN: 1100956 ...........................................................................................................6 100 MΩ STANDARD – SN: 1100587 .........................................................................................................7 100 MΩ STANDARD – SN: 69318 .............................................................................................................7 1 GΩ STANDARD – SN: HR9107 ..............................................................................................................8 1 GΩ STANDARD – SN: HR9203 ..............................................................................................................8 7. REPORTED RESULTS OF COMPARISONS.................................................................................9 RESULTS AT 1 MΩ ...................................................................................................................................9 RESULTS AT 10 MΩ ............................................................................................................................... 10 RESULTS AT 100 MΩ ............................................................................................................................. 11 RESULTS AT 1 GΩ .................................................................................................................................. 11 8. REFERENCES ................................................................................................................................ 12 APPENDIX A ............................................................................................................................................ 13 HRCCC INSTRUCTIONS..........................................................................................................................13 BRIDGE CONNECTIONS ........................................................................................................................... 13 APPENDIX B ............................................................................................................................................ 21
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1. Introduction
This work presents a supplementary comparison of high value resistance standard performed during 2012 and January 2013. It was performed following the guidelines presented in a document about measurement comparisons in the CIPM MRA [1]. The purpose of this task was to compare the high resistance cryogenic current comparator scaling of the participating institutes, National Institute of Standards and Technology – U.S.A. (NIST), Centro Nacional de Metrología – Mexico (CENAM), Instituto Nacional de Tecnología Industrial – Argentina (INTI), all of which are members of the Sistema Interamericano de Metrología (SIM) Regional Metrology Organization.
All the measurements of this comparison were performed with two-terminal Cryogenic Current Comparators (CCC) [2]. They were developed in a frame of an international cooperation project during the years 2007 and 2008. This project includes the participating institutes and the National Measurement Institute of Australia (NMI).
2. Participating Laboratories
The following table shows the participated institutes and the average date of measurement. The pilot laboratory (NIST), measured the resistors three times closing loops with each participating institute.
Average date
August 2012
October 2012
November 2012
December 2012
January 2013
National Metrology Institute
National Institute of Standards and Technology (Pilot), U. S. A.
Centro Nacional de Metrología, México.
National Institute of Standards and Technology (Pilot), U. S. A.
Instituto Nacional de Tecnología Industrial, Argentina.
National Institute of Standards and Technology (Pilot), U. S. A.
Institute NIST
CENAM NIST INTI NIST
3. Traveling standards
In order to provide a complete evaluation of the systems and redundancy at each resistance level [3], two traveling standards of each decade value between 1 MΩ and 1 GΩ were selected. These resistors were NIST-constructed hermetically sealed standards [4] or commercial film-type standards of similar construction and quality. The standard resistors were selected by the pilot laboratory. They must have low and linear drift, low temperature coefficient and negligible time constant. This last point is crucial because the bridge must invert voltage polarity at intervals of about 10 s to 50 s in order to reduce the effect of low frequency drift in the SQUID voltage. Typical values of delay time between voltage inversion and measurement are between 4 and 30 s. In order to reduce high frequency noise and the standard deviation of measurements, resistors with nominal value bigger than 1 MΩ were
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equipped with coaxial connectors. Resistor manufacturers1, models and temperature coefficients are detailed in Table 2.
Manufacturer
Model
Nominal Alpha Beta value [µΩ/K] [µΩ/K2]
Fluke
742A-1M
1 MΩ 0.209 -0.008
Fluke
742A-1M
1 MΩ 0.086 -0.040
MIL
9331G/10M 10 MΩ 1.283
MIL
9331G/10M 10 MΩ 0.779
MIL
9331G/100M 100 MΩ 2.482
Guildline
9336
100 MΩ 5.103
NIST
NIST HR 1G 1 GΩ 25.032
NIST
NIST HR 1G 1 GΩ 29.550
Table 2: specification of the traveling standard resistors.
4. Description of the transport package
A heavy plastic shipping container was filled with plastic foam for protection of the comparison standards. The transport case contained the eight standard resistors and a recorder of temperature and relative humidity. This recorder was used to monitor the environmental conditions during transport.
5. Measurement procedures and instruction
Measurements were performed at direct current with a two-terminal cryogenic current comparator using the methods developed in the cooperative project. These methods are described in Appendix A. The measurement results are expressed in terms of the conventional value of the von Klitzing constant. The scaling process starts with a quantized Hall resistance (QHR) standard maintained in each of the respective laboratories or 10 kΩ standard resistors measured with respect to the QHR. In this comparison, each institute has an independent resistance realization. The standards were conditioned in an air-bath or at ambient laboratory conditions for at least 24 h, the inner temperature of the resistors were not measured in any case. The results were adjusted for the temperature deviation using the TCR of each standard. All the resistors where measured at 10 V, with exception of the 1 MΩ resistors at INTI that were measured at 5 V due limitation in the system. No voltage correction was applied in any resistor. Measurements were repeated at least four times during the period allocated to the participating laboratory, approximately three to four weeks. Environmental conditions and standard deviation was recorded at each measurement.
6. Measurement results
The corrected measurement value, expanded uncertainty and medium date of measurement of each NMI for traveling standards are listed below. The uncertainty budget for each NMI is shown in Appendix B.
1 Commercial equipment may be identified in this paper to specify the experimental procedure adequately. Such identification is not intended to imply recommendation or endorsement, or that the equipment is necessarily the best available for the purpose.
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1 MΩ standard – SN: 8409005
Medium date
17-Aug-12 11-Oct-12 20-Nov-12 20-Dec-12 27-Jan-13
Value [MΩ] 1.00000433 1.00000445 1.00000480 1.00000453 1.00000487
NMI
NIST CENAM
NIST INTI NIST
U (k=2) [µΩ/Ω]
0.13 0.25 0.13 0.27 0.13
5.00
Correction at nominal value [µΩ/Ω]
4.80
4.60
4.40
4.20 10-Jul
29-Aug 18-Oct 7-Dec
Date
26-Jan 17-Mar
Figure 1: measurement chart to the standard resistor 8409005.
1 MΩ standard – SN: 8409007
Medium date
17-Aug-12 11-Oct-12 20-Nov-12 20-Dec-12 27-Jan-13
Value [MΩ] 1.00000250 1.00000257 1.00000280 1.00000263 1.00000275
NMI
NIST CENAM
NIST INTI NIST
U (k=2) [µΩ/Ω]
0.13 0.25 0.13 0.26 0.13
5
Correction at nominal value [µΩ/Ω]
2.90 2.75
2.60
2.45
2.30 10-Jul
29-Aug
18-Oct 7-Dec
Date
26-Jan 17-Mar
Figure 2: measurement chart to the standard resistor 8409007.
10 MΩ standard – SN: 1100955
Medium date
6-Aug-12 26-Oct-12 20-Nov-12 19-Dec-12 27-Jan-13
Value [MΩ] 10.0000921 10.0001067 10.0000978 10.0001017 10.0001083
NMI
NIST CENAM
NIST INTI NIST
U (k=2) [µΩ/Ω]
0.18 0.54 0.18 0.45 0.18
Correction at nominal value [µΩ/Ω]
11.4 10.8 10.2
9.6 9.0
10-Jul 29-Aug 18-Oct 7-Dec 26-Jan 17-Mar
Date
Figure 3: measurement chart to the standard resistor 1100955.
10 MΩ standard – SN: 1100956
Medium date
3-Aug-12 26-Oct-12 20-Nov-12 20-Dec-12 26-Jan-13
Value [MΩ] 10.0000995 10.0001150 10.0001075 10.0001102 10.0001150
NMI
NIST CENAM
NIST INTI NIST
U (k=2) [µΩ/Ω]
0.14 0.52 0.14 0.39 0.14
6
12.0
Correction at nominal value [µΩ/Ω]
11.4
10.8
10.2
9.6 10-Jul
29-Aug
18-Oct 7-Dec
Date
26-Jan 17-Mar
Figure 4: measurement chart to the standard resistor 1100956.
100 MΩ standard – SN: 1100587
Medium date
Value [MΩ]
5-Aug-12 100.00164
28-Oct-12 100.00181
21-Nov-12 100.00179
20-Dec-12 100.00156 27-Jan-13 100.00200
NMI
NIST CENAM
NIST INTI NIST
U (k=2) [µΩ/Ω]
0.4 1.2 0.4 1.0 0.4
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Correction at nominal value [µΩ/Ω]
19
17
15 10-Jul
29-Aug
18-Oct 7-Dec
Date
26-Jan 17-Mar
Figure 5: measurement chart to the standard resistor 1100587.
100 MΩ standard – SN: 69318
Medium date
Value [MΩ]
5-Aug-12 100.00341
28-Oct-12 100.00362
20-Nov-12 100.00352
20-Dec-12 100.00349 26-Jan-13 100.00376
NMI
NIST CENAM
NIST INTI NIST
U (k=2) [µΩ/Ω]
0.6 1.6 0.6 1.7 0.6
7
39
Correction at nominal value [µΩ/Ω]
37
35
33 10-Jul
29-Aug
18-Oct 7-Dec
Date
26-Jan 17-Mar
Figure 6: measurement chart to the standard resistor 69318.
1 GΩ standard – SN: HR9107
Medium date
6-Aug-12 30-Oct-12 20-Nov-12 19-Dec-12 27-Jan-13
Value [GΩ] 0.999725 0.999732 0.999742 0.999730 0.999750
NMI
NIST CENAM
NIST INTI NIST
U (k=2) [µΩ/Ω]
4 9 4 7 4
-244
Correction at nominal value [µΩ/Ω]
-256
-268
-280 10-Jul
29-Aug 18-Oct 7-Dec
Date
26-Jan 17-Mar
Figure 7: measurement chart to the standard resistor HR9107.
1 GΩ standard – SN: HR9203
Medium date
6-Aug-12 1-Nov-12 20-Nov-12 20-Dec-12 27-Jan-13
Value [GΩ] 0.999358 0.999361 0.999369 0.999355 0.999369
NMI
NIST CENAM
NIST INTI NIST
U (k=2) [µΩ/Ω]
4 8 4 7 4
8
-624
Correction at nominal value [µΩ/Ω]
-634
-644
-654 10-Jul
29-Aug 18-Oct 7-Dec
Date
26-Jan 17-Mar
Figure 8: measurement chart to the standard resistor HR9203.
7. Reported results of comparisons
The statistical analysis of this comparison followed closely that employed for key comparison CCEM-K2 [3-5]. First, a linear trend was calculated from the measurements of the pilot laboratory using a least squares algorithm. Next, the resistor trend values at the average date of measurement of each institute were estimated and differences between these and the measured values for each institute were calculated. At each resistance level two differences were obtained and they were combined with a weighted sum, with more weight given to that resistor with less residual variance in the linear estimation. An uncertainty was calculated from the combined differences and was used to calculate the relative weight of each institute. The comparison reference value (CRV) was calculated as a weighted sum of the combined differences. Finally, the degree of equivalence was obtained subtracting the CRV to the combined difference.
Following the comparison reference value, its uncertainty and the degree of equivalence with respect to the CRV are included.
Results at 1 MΩ
Comparison reference value: -0.031 Ω. Expanded uncertainty of CRV: 0.11 Ω. Degree of equivalence with respect to the CRV:
NMI
CENAM INTI NIST
[µΩ/Ω]
-0.06 -0.16 0.03
U (k=2) [µΩ/Ω]
0.30 0.32 0.06
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Degree of equivalence [µΩ/Ω]
0.40 0.20 0.00 -0.20 -0.40 -0.60
-0.06 CENAM
0.03 -0.16
INTI
NIST
Figure 9: degree of equivalence with respect to the CRV at 1 MΩ level.
Results at 10 MΩ
Comparison reference value: 0.53 Ω. Expanded uncertainty of CRV: 1.64 Ω. Degree of equivalence with respect to the CRV:
NMI
CENAM INTI NIST
[µΩ/Ω]
0.81 -0.15 -0.05
U (k=2) [µΩ/Ω]
0.58 0.50 0.08
1.50
Degree of equivalence [µΩ/Ω]
1.00 0.81
0.50
0.00 -0.50
-0.15
-0.05
-1.00
CENAM
INTI
NIST
Figure 10: degree of equivalence with respect to the CRV at 10 MΩ level.
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Results at 100 MΩ
Comparison reference value: -20.4 Ω. Expanded uncertainty of CRV: 54.1 Ω. Degree of equivalence with respect to the CRV:
NMI
CENAM INTI NIST
[µΩ/Ω]
0.6 -2.7 0.2
U (k=2) [µΩ/Ω]
1.7 1.8 0.3
Degree of equivalence [µΩ/Ω]
4.0
2.0
0.0
0.6
-2.0
-4.0
-6.0 CENAM
0.2 -2.7
INTI
NIST
Figure 11: degree of equivalence with respect to the CRV at 100 MΩ level.
Results at 1 GΩ
Comparison reference value: -3244 Ω. Expanded uncertainty of CRV: 3417 Ω. Degree of equivalence with respect to the CRV:
NMI
CENAM INTI NIST
[µΩ/Ω]
-2.6 -11.8 3.2
U (k=2) [µΩ/Ω]
8.0 7.8 2.3
11
Degree of equivalence [µΩ/Ω]
7.0 3.2
0.0 -2.6
-7.0
-14.0
-11.8
-21.0
CENAM
INTI
NIST
Figure 12: degree of equivalence with respect to the CRV at 1 GΩ level.
8. References
[1] Measurement comparisons in the context of the CIPM MRA, CIPM MRA-D-05, 2012. [2] M. E. Bierzychudek and R. E. Elmquist, “Uncertainty evaluation in a two-terminal cryogenic current comparator,” IEEE Trans. Instrum. Meas., vol. 58, no. 4, pp. 1170 – 1175, April 2009. [3] N. F. Zhang, N. Sedransk and D. Jarrett, “Statistical uncertainty analysis of key comparison CCEM-K2”, IEEE Trans. Instrum. Meas., vol. 52, no. 2, pp. 491-494, April 2003. [4] R. Dziuba, D. Jarrett, L. Scott and A. Secula, “Fabrication of high-value standard resistors”, IEEE Trans. Instrum. Meas., vol. 48, no. 2, pp. 333-337, April 1999. [5] R. F. Dziuba and D. G. Jarrett, CCEM-K2 Key Comparison of Resistance Standards at 10 MΩ and 1 GΩ, Jul. 2001. [Online]. Available: http://kcdb.bipm.org/appendixB/appbresults/ccem-k2/ccem-k2\_final\_report.pdf.
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Appendix A
HRCCC Instructions
May 2013
Bridge connections
Particulars connections have to be performed to the measurement of the coil resistance and voltage source. They are explained next.
• The HRCCC electronic has to be connected to the PC via a KEITHLEY relay board.
• The front channel of the high accuracy multimeter has to be connected to the BNC-OUT.
• The SQUID controller (BNC-SIGNAL OUT) has to be connected to the HRCCC electronics (BNC-SQUID). Also, the BNC-DETECTOR can be connected to an oscilloscope.
Calibration of coil and lead resistances
The proposed method uses the multimeter 3458A. It is also possible to use a more accurate system, such as the MI-6010 bridge. In tests at NIST the DMM method gave equivalent results, after the ACAL procedure. Setup
1. Perform the ACAL procedure in the DVM. 2. Source and feedback switches in “off” position. 3. Source voltage knob in 10 V position (or other HIGH RANGE). This
removes the diode protection in parallel to the coils. 4. CCC cable connected to “CCC” LEMO connector on electronics unit. 5. DMM cable connected to “R-CCC” LEMO connector. 6. 4-wire connection to DMM rear panel, red connected to input binding post
and green connected to Ohm Sense. CCC connections
1. One coil must be shorted at the resistor connection point. 2. For four-terminal resistors, make a short using same-side V&I terminals. 3. Otherwise, short the leads as close as possible to the resistor. 4. For 100 kΩ and below, measure winding resistance at each resistor. Measurements 1. Select “Winding Res” on the CCC Setup page. 2. Set range and delay for automatic DMM measurements. 3. Enter the information to identify the “winding” and “resistor”. 4. Run until result is stable (best if start with 3100 turn winding – lower
resistance windings may induce heating when measured). 5. Results are stored in “QCoilLeadRes.csv” file in “CCC data” folder. Examples: 1. Primary 3100 turn lead, DMM range 10 kΩ; make 20 measurements with
10 s delay for the shorted leads at one terminal of 1 MΩ resistor. 2. Secondary 31 turn lead; DMM range 100 Ω; make 10 measurements for each
resistor, measured with the short formed inside the resistor if they are 4-
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terminal type, so the correction is accurate. For all higher values, the lead resistance for the 1 MΩ resistor may be used. The CCC may cause trapped flux in the SQUID when coil resistances are measured. To remove trapped flux, turn down the SQUID Bias to zero and press the heater button for about five seconds, then adjust the Bias for maximum signal.
Connection to the measurement of the voltage source
Connect the resistors for measurement and connect the potential (Green) terminals of the RCCC cable to the back of the DVM (voltage inputs). Using the Red terminals in the main measurement to sense the voltage will cause an error, because there is a voltage drop in the CCC leads.
Turning on the Electronics Unit
1. Unplug the battery charger, either at the wall or at the unit. 2. Turn off the Charger switch, and turn on the Feedback and Source switches. 3. If the CCC cable is disconnected from the unit, it is best to turn the source and
feedback off before reconnecting the CCC cable. The SQUID noise is sometimes increased otherwise, and turning the unit off and then on will eliminate this noise. 4. The yellow LEDs that show the status of the Integrator Zero and Reset conditions of the unit should be lit when the source is turned on. The green LED (POS) that shows the direction of the source voltage should be lit. The red LED that indicates the voltage range (High Range) should be lit if the voltage is set to 1.1 V, 5 V, or 10 V. 5. The BNC cable marked DVM should connect to the front voltage input of the DVM.
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Program setup
The CCC is operated using a compiled program written in Visual Basic. When the program is activated it opens the Setup Screen shown below.
Some of the content in the drop-down boxes is read from a configuration file, MEGCCC3100IIStartForm.cfg. For example, this file is read at startup to fill the contents of the drop-down boxes labeled “Windings” and “Winding Resistance”.
Some boxes on this form can be modified by entering values or text. When the measurement is complete, the latest entry in these boxes is saved in the configuration file or in the resistor database.
Winding resistance values depend on the winding that is selected. Whenever the user changes these values, the new values will be saved in the configuration file after the measurement is completed. The number of DMM readings “Readings”, “Detector Settings”, and “Program Conditions” are also saved and will be loaded the next time the measurement runs, even if the program is reloaded.
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The “Program Conditions” box controls the data-taking process and run-time analysis. The “SQUID Check” value is the maximum offset of the integrator output voltage (DMM voltage reading) for the first reading after the integrator is zeroed. This checks that the SQUID was zeroed at the start of the run.
Two settings that control automatic filtering of the data are the “Error Limit” and “Drift”. The analysis calculates the variance of the set of DVM readings (number of readings set by “Current Readings”) and compares it to the variance calculated with one fewer reading (eliminating the reading with largest residual). This difference is compared to the “Error Limit” – if the variance is reduced by more than the “Error Limit”, that reading is eliminated. This can continue until the remaining number of readings is two. The “Drift” variable is used when comparing the first and last data sets of the four sets of DVM readings that go into the resistance calculation. If the change from set 1 to set 4 is twice the level set by the “Drift” variable, then set 1 and set 2 are thrown out. Set 3 and set 4 become the new set 1 and set 2. This is intended to eliminate data that includes a flux jump in the SQUID, but also could eliminate data where the SQUID is drifting rapidly.
Number of DVM readings in a data set
Maximum DVM reading (V) for initialization of integrator
Minimum reduction in variance of DVM reading for filtering to be used on a data set
Filter to eliminate SQUID jumps
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Controllers made by NI and Hewlett Packard that run from a USB port can both use the NI drivers
Comments remain until changed or program is reloaded
Select which resistor will be used as the standard of reference
Select to read thermometer or enter a temperature
Sign of feedback current in ratio calculations – the same unless input to SQUID changed
Select Windings first, then Primary Resistor
Then select the SN of the two resistors, or add a new resistor by typing its SN into the appropriate box, and enter the resistance or PPM correction
Select when to measure the Source Voltage and chose the Source Voltage setting to match the switch position on the unit
Once the setup process is complete for the measurement, press the “Start” button.
You will be prompted to connect and disconnect the DMM rear-panel cable that
measures the bridge voltage if you selected the “Before” option in the “Source Voltage
Test” area of the “Setup” screen. It is important that the source voltage is stable, so the
source should be turned on at least ten minutes before the bridge voltage is measured.
When voltage calibration is complete, the measurement screen will appear over the
“Setup”
screen.
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Measurement (Run) Screen
A message box will prompt you to engage and zero the SQUID flux-lock as this screen loads. Once the SQUID feedback is locked (zero voltage out of the SQUID) the data sequence begins. It will run until the user clicks the “New Resistor” button or the “Stop” button. Both commands will allow the program to run until the source voltage goes to zero at a current reversal. At that time, a red box appears with the message that the sequence is complete.
Display the data in graphical form by clicking the “Show Plot” button. The scale will depend on the resistor value, winding number, and source voltage level. The scale should allow all data to show on the plot unless there is drift or excess noise. The “Auto Scale” button below the plot increases or decreases the scale so that all data is on scale, with a minimum of 1 µΩ/Ω full-scale. New max/min values can also be entered manually.
New Resistor button
Show/Hide plot button
Stop button
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The next screenshot shows the “Run” screen when the run is completed, after “New Resistor” was selected. It shows the effect of the “Auto Scale” button on the plot of the data set. Note this is the same data set shown on the last page.
The program pauses at the end of the run, after “New Resistor” is clicked and the source voltage is zeroed, to allow you to review the data set and delete points if necessary. If a data point is excessively noisy, double-clicking on that data point on the graph will mark that point and it will be omitted from the average and standard deviation calculated for the run. The selected point or points will be shown in red. “Auto Scale” makes all of the data points visible, so that extreme points can be viewed and discarded.
The “Test Resistors” box, “Standard Resistor” box and many other fields on the Run page cannot be altered, and are for your information only.
Additional user comments can be added in the box on the Run screen. These will be appended to the comment from the Setup screen, but this comment field does not carry over to the next run. The comments on the setup screen carry over until they are changed.
Unknown R, correction values using all four DVM readings
Unknown R, using first and third DVM readings only
Unknown R, using second and fourth DVM readings only
Feedback currents used to calculate R values
Remaining unfiltered
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Continue to the next run, or to the “After” voltage calibration
When the “Continue” button is pressed, the program completes the data set, making “After” voltage calibrations if necessary. The data set is stored in two files with differing levels of compression. Any deleted points will be marked in the data files, and the average values and standard deviations exclude these points.
Charging the batteries
When the charger switch on the back panel is turned on, all of the lines from the batteries are disconnected from the circuits and the other switches. The battery charger circuits are connected to the batteries, and a LED light connected to one of the 6 V lines that leads to a charger will come on. This LED is also on if the battery chargers are connected to the 115 V power line.
To charge the batteries, turn the Source and Feedback switches to the off position, and turn on the Charger switch. The chargers are designed to sense the condition of the batteries when the AC power is first turned on. After turning on the Charger switch connect the power cord to the fused receptacle on the back panel. The fuse should be a 1.5 A or less slow-blow fuse. The batteries that are used to power the feedback and source circuits have a common ground that is connected to the electronics enclosure. The communications circuit is isolated from this common ground, except when the 6 V battery is being charged. Be sure to supply power at 110 V to 120 V, using a step-down transformer if necessary.
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Appendix B
In this appendix the budget uncertainty to each resistor and institute is shown.
Serial number: 8409005 Nominal value: 1 MΩ
CENAM - Mexico
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.100
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.002
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.070
Rectangular/B
1
Reference temperature [ºC]
0.083
Normal/B
0.209 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.011
Normal/A
1
Repeatability [µΩ/Ω]
0.015
Normal/B
1
Temperature
correction
0.006
Normal/B
0.1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.100
Degrees of freedom
νi
∞
0.002
∞
0.070
∞
0.017
∞
0.011
20
0.015
5
0.001
∞
0.125
∞
0.249 µΩ/Ω
NIST - USA
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.025
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.025
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.010
Normal/B
1
Reference temperature [ºC]
0.050
Normal/B
0.209 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.008
Normal/A
1
Repeatability [µΩ/Ω]
0.049
Normal/B
1
Temperature
correction
0.006
Normal/B
0.02 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.025
Degrees of freedom
νi
∞
0.025
50
0.010
∞
0.010
∞
0.008
22
0.049
22
0.000
∞
0.063
∞
0.125 µΩ/Ω
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INTI - Argentina
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.045
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.008
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.114
Normal/B
1
Reference temperature [ºC]
0.107
Normal/B
0.209 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.048
Normal/A
1
Repeatability [µΩ/Ω]
0.024
Normal/B
1
Temperature
correction
0.006
Normal/B
1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.045
Degrees of freedom
νi
∞
0.008
∞
0.114
∞
0.022
∞
0.048
3
0.024
3
0.006
∞
0.136
64
0.272 µΩ/Ω
22
Serial number: 8409007 Nominal value: 1 MΩ
CENAM - Mexico
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.100
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.002
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.070
Rectangular/B
1
Reference temperature [ºC]
0.045
Normal/B
0.086 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.011
Normal/A
1
Repeatability [µΩ/Ω]
0.019
Normal/B
1
Temperature correction
[µΩ/Ω per ºC]
0.006
Normal/B
0.1 ºC
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.100
Degrees of freedom
νi
∞
0.002
∞
0.070
∞
0.004
∞
0.011
20
0.019
5
0.001
∞
0.124
∞
0.248 µΩ/Ω
NIST - USA
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.025
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.025
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.010
Normal/B
1
Reference temperature [ºC]
0.050
Normal/B
0.086 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.006
Normal/A
1
Repeatability [µΩ/Ω]
0.048
Normal/B
1
Temperature
correction
0.006
Normal/B
0.02 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.025
Degrees of freedom
νi
∞
0.025
50
0.010
∞
0.004
∞
0.006
22
0.048
22
0.000
∞
0.061
∞
0.122 µΩ/Ω
23
INTI - Argentina
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.045
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.008
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.114
Normal/B
1
Reference temperature [ºC]
0.107
Normal/B
0.086 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.036
Normal/A
1
Repeatability [µΩ/Ω]
0.016
Normal/B
1
Temperature
correction
0.006
Normal/B
1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.045
Degrees of freedom
νi
∞
0.008
∞
0.114
∞
0.009
∞
0.036
3
0.016
3
0.006
∞
0.129
69
0.258 µΩ/Ω
24
Serial number: 1100955 Nominal value: 10 MΩ
CENAM - Mexico
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.130
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.100
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.020
Rectangular/B
1
Reference temperature [ºC]
0.043
Normal/B
1.283 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.059
Normal/A
1
Repeatability [µΩ/Ω]
0.195
Normal/B
1
Temperature
correction
0.050
Normal/B
0.1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.130
Degrees of freedom
νi
∞
0.100
∞
0.020
∞
0.055
∞
0.059
50
0.195
7
0.005
∞
0.268
∞
0.536 µΩ/Ω
NIST - USA
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.025
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.025
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.010
Normal/B
1
Reference temperature [ºC]
0.050
Normal/B
1.283 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.008
Normal/A
1
Repeatability [µΩ/Ω]
0.050
Normal/B
1
Temperature
correction
0.050
Normal/B
0.02 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.025
Degrees of freedom
νi
∞
0.025
50
0.010
∞
0.064
∞
0.008
19
0.050
19
0.001
∞
0.090
∞
0.179 µΩ/Ω
25
INTI - Argentina
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.123
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.022
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.020
Normal/B
1
Reference temperature [ºC]
0.107
Normal/B
1.283 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.108
Normal/A
1
Repeatability [µΩ/Ω]
0.005
Normal/B
1
Temperature
correction
0.050
Normal/B
1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.123
Degrees of freedom
νi
∞
0.022
∞
0.020
∞
0.137
∞
0.108
4
0.005
4
0.050
∞
0.222
52
0.445 µΩ/Ω
26
Serial number: 1100956 Nominal value: 10 MΩ
CENAM - Mexico
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.130
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.100
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.020
Rectangular/B
1
Reference temperature [ºC]
0.027
Normal/B
0.779 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.056
Normal/A
1
Repeatability [µΩ/Ω]
0.190
Normal/B
1
Temperature
correction
0.050
Normal/B
0.1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.130
Degrees of freedom
νi
∞
0.100
∞
0.020
∞
0.021
∞
0.056
50
0.190
7
0.005
∞
0.259
∞
0.518 µΩ/Ω
NIST - USA
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.025
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.025
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.010
Normal/B
1
Reference temperature [ºC]
0.050
Normal/B
0.779 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.008
Normal/A
1
Repeatability [µΩ/Ω]
0.044
Normal/B
1
Temperature
correction
0.050
Normal/B
0.02 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.025
Degrees of freedom
νi
∞
0.025
50
0.010
∞
0.039
∞
0.008
21
0.044
21
0.001
∞
0.070
∞
0.140 µΩ/Ω
27
INTI - Argentina
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.123
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.022
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.020
Normal/B
1
Reference temperature [ºC]
0.107
Normal/B
0.779 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.100
Normal/A
1
Repeatability [µΩ/Ω]
0.030
Normal/B
1
Temperature
correction
0.050
Normal/B
1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.123
Degrees of freedom
νi
∞
0.022
∞
0.020
∞
0.083
∞
0.100
3
0.030
3
0.050
∞
0.191
33
0.388 µΩ/Ω
28
Serial number: 1100587 Nominal value: 100 MΩ
CENAM - Mexico
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.250
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.160
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.100
Rectangular/B
1
Reference temperature [ºC]
0.025
Normal/B
2.482 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.400
Normal/A
1
Repeatability [µΩ/Ω]
0.300
Normal/B
1
Temperature
correction
0.100
Normal/B
0.1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.250
Degrees of freedom
νi
∞
0.160
∞
0.100
∞
0.062
∞
0.400
35
0.300
9
0.010
∞
0.593
∞
1.187 µΩ/Ω
NIST - USA
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.025
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.025
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.100
Normal/B
1
Reference temperature [ºC]
0.050
Normal/B
2.482 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.049
Normal/A
1
Repeatability [µΩ/Ω]
0.120
Normal/B
1
Temperature
correction
0.100
Normal/B
0.02 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.025
Degrees of freedom
νi
∞
0.025
50
0.100
∞
0.124
∞
0.049
16
0.120
16
0.002
∞
0.209
∞
0.418 µΩ/Ω
29
INTI - Argentina
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.126
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.137
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.157
Normal/B
1
Reference temperature [ºC]
0.107
Normal/B
2.482 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.256
Normal/A
1
Repeatability [µΩ/Ω]
0.120
Normal/B
1
Temperature
correction
0.100
Normal/B
1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.126
Degrees of freedom
νi
∞
0.137
∞
0.157
∞
0.266
∞
0.256
3
0.120
3
0.100
∞
0.469
30
0.959 µΩ/Ω
30
Serial number: 69318 Nominal value: 100 MΩ
CENAM - Mexico
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.250
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.160
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.100
Rectangular/B
1
Reference temperature [ºC]
0.027
Normal/B
5.103 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.484
Normal/A
1
Repeatability [µΩ/Ω]
0.542
Normal/B
1
Temperature
correction
0.100
Normal/B
0.1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.250
Degrees of freedom
νi
∞
0.160
∞
0.100
∞
0.138
∞
0.484
35
0.542
8
0.010
∞
0.803
∞
1.606 µΩ/Ω
NIST - USA
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.025
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.025
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.100
Normal/B
1
Reference temperature [ºC]
0.050
Normal/B
5.103 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.060
Normal/A
1
Repeatability [µΩ/Ω]
0.100
Normal/B
1
Temperature
correction
0.100
Normal/B
0.02 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.025
Degrees of freedom
νi
∞
0.025
50
0.100
∞
0.255
∞
0.060
17
0.100
17
0.002
∞
0.300
∞
0.600 µΩ/Ω
31
INTI - Argentina
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.126
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.137
Normal/B
1
Measuring apparatus [µΩ/Ω]
0.157
Normal/B
1
Reference temperature [ºC]
0.107
Normal/B
5.103 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.461
Normal/A
1
Repeatability [µΩ/Ω]
0.322
Normal/B
1
Temperature
correction
0.100
Normal/B
1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution u(Ri) [µΩ/Ω]
0.126
Degrees of freedom
νi
∞
0.137
∞
0.157
∞
0.546
∞
0.461
3
0.322
3
0.100
∞
0.827
23
1.715 µΩ/Ω
32
Serial number: HR9107 Nominal value: 1 GΩ
CENAM - Mexico
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.600
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.140
Normal/B
1
Measuring apparatus [µΩ/Ω]
1.000
Rectangular/B
1
Reference temperature [ºC]
0.024
Normal/B
25.032 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
3.470
Normal/A
1
Repeatability [µΩ/Ω]
2.130
Normal/B
1
Temperature
correction
0.700
Normal/B
0.1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.600
Degrees of freedom
νi
∞
0.140
∞
1.000
∞
0.600
∞
3.470
40
2.130
8
0.070
∞
4.337
∞
8.673 µΩ/Ω
NIST - USA
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.080
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.025
Normal/B
1
Measuring apparatus [µΩ/Ω]
1.000
Normal/B
1
Reference temperature [ºC]
0.050
Normal/B
25.032 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
0.484
Normal/A
1
Repeatability [µΩ/Ω]
1.230
Normal/B
1
Temperature
correction
0.700
Normal/B
0.02 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.080
Degrees of freedom
νi
∞
0.025
50
1.000
∞
1.252
∞
0.484
19
1.230
19
0.014
∞
2.081
∞
4.162 µΩ/Ω
33
INTI - Argentina
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.244
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.266
Normal/B
1
Measuring apparatus [µΩ/Ω]
1.562
Normal/B
1
Reference temperature [ºC]
0.107
Normal/B
25.032 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
1.816
Normal/A
1
Repeatability [µΩ/Ω]
0.321
Normal/B
1
Temperature
correction
0.700
Normal/B
1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution u(Ri) [µΩ/Ω]
0.244
Degrees of freedom
νi
∞
0.266
∞
1.562
∞
2.681
∞
1.816
4
0.321
4
0.700
∞
3.694
48
7.428 µΩ/Ω
34
Serial number: HR9203 Nominal value: 1 GΩ
CENAM - Mexico
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.600
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.140
Normal/B
1
Measuring apparatus [µΩ/Ω]
1.000
Rectangular/B
1
Reference temperature [ºC]
0.025
Normal/B
29.550 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
2.970
Normal/A
1
Repeatability [µΩ/Ω]
2.341
Normal/B
1
Temperature
correction
0.700
Normal/B
0.1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.600
Degrees of freedom
νi
∞
0.140
∞
1.000
∞
0.740
∞
2.970
40
2.341
7
0.070
∞
4.089
∞
8.178 µΩ/Ω
NIST - USA
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.080
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.025
Normal/B
1
Measuring apparatus [µΩ/Ω]
1.000
Normal/B
1
Reference temperature [ºC]
0.050
Normal/B
29.550 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
Repeatability [µΩ/Ω]
Temperature correction
[µΩ/Ω per ºC]
0.477 0.960 0.700
Normal/A Normal/B Normal/B
1 1 0.02 ºC
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution
u(Ri) [µΩ/Ω]
0.080
Degrees of freedom
νi
∞
0.025
50
1.000
∞
1.478
∞
0.477
17
0.960
17
0.014
∞
2.085
∞
4.171 µΩ/Ω
35
INTI - Argentina
Standard uncertainty
Distribution /method of evaluation
Sensitivity coefficient
Influence factor yi
u(yi)
Method/(A, B)
ci
Scaling / traceability [µΩ/Ω]
0.244
Normal/B
1
Reference standard(s) [µΩ/Ω]
0.266
Normal/B
1
Measuring apparatus [µΩ/Ω]
1.562
Normal/B
1
Reference temperature [ºC]
0.107
Normal/B
29.550 µΩ/Ω per ºC
Standard deviation [µΩ/Ω]
1.460
Normal/A
1
Repeatability [µΩ/Ω]
0.007
Normal/B
1
Temperature
correction
0.700
Normal/B
1 ºC
[µΩ/Ω per ºC]
Combined standard uncertainty and effective degrees of freedom:
Expanded uncertainty (95 % coverage factor):
Uncertainty contribution u(Ri) [µΩ/Ω]
0.244
Degrees of freedom
νi
∞
0.266
∞
1.562
∞
3.164
∞
1.460
3
0.007
3
0.700
50
3.899
63
7.792 µΩ/Ω
36
Ver+/-
