| Título: | SIM.EM – S10 : RMO Comparison final report. High value resistance comparison with twoterminal cryogenic current comparators |
| Fuente: | Metrología, 51 |
| Autor/es: | Bierzychudek, Marcos E.; Elmquist, Randolph; Hernández, Felipe |
| Materias: | Sistema Interamericano de Metrología; Metrología; Calibración; Patrones; Comparadores; Resistores; Criogenia |
| Editor/Edición: | IOP Publishing; 2014 |
| Licencia: | https://creativecommons.org/licenses/by/3.0/ |
| Afiliaciones: | Bierzychudek, Marcos E. Instituto Nacional de Tecnología Industrial (INTI); Argentina Elmquist, Randolph. National Institute of Standards and Technology (NIST); Estados Unidos Hernández, Felipe. Centro Nacional de Metrología (CENAM); México |
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| Resumen: | This work presents a supplementary comparison of high value resistance standards performed during 2012 and January 2013, following the guidelines presented in a document about measurement comparisons in the CIPM MRA. 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, USA (NIST), Centro Nacional de Metrología, Mexico (CENAM) and 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). Degrees of equivalence of the participating institutes relative to the comparison reference values are given in the report for the measured resistance values. |
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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 1 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 2 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 3 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. 4 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 21 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 9 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. 10 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. 12 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- 13 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. 14 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. 15 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 16 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. 17 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 18 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 19 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. 20 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 21 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 36Ver+/- |
