AC-DC Current Transfer Standards Research Articles

APMP key comparison of AC-DC current transfer standards: final report

Main textThis report summarizes the results and performances of APMP.EM-K12, APMP key comparison of AC-DC current transfer standards of 10 mA and 5 A at frequencies of 10 Hz, 55 Hz, 1 kHz, 10 kHz, 20 kHz, 50 kHz, and 100 kHz. Ten National Metrology Institutes participated in this key comparison, including NMC/A*STAR (Singapore, pilot Laboratory), NMIA (Australia), SCL (Hong Kong, China), NMIJ (Japan), KRISS (Rep of Korea), NIM (China), NMISA (South Africa), NIMT (Thailand), NMIM (Malaysia), and CMS/ITRI (Chinese Taipei). The key comparison is linked to the CCEM one, CCCEM-K12, with same measurement quantities through the performances of two laboratories, NMC and NMIA, in both key comparisons. The degrees of equivalence of individual participating laboratories with the reference values of CCEM-K12 were thus concluded in this report.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

High accuracy AC current sources calibration by single junction thermal converters at INM

The National Metrology Institute of Colombia (INM) uses high accuracy calibrators (such as Fluke 5720A/5730A) as AC current reference standards. We describe the implementation at INM of AC-DC current transfer standards by single junction thermal converters (SJTC) to improve the accuracy of AC measurements and give traceability to the International System of Units (SI) within the country. We describe the measurement model, present the uncertainty budget estimation accordingly to the Guide to the Expression of Uncertainty in Measurement (GUM) and analyze the effect of temperature and electrostatic on measurements. Expanded uncertainties between 68 μA/A and 2.6 mA/A were obtained for the calibration of high accuracy calibrators and transconductance amplifiers for currents from 5 mA to 20 A (40 Hz to 5 kHz). The obtained measurement results are compatible with calibration results from the National Metrology Institutes like Centro Nacional de Metrología from Mexico (CENAM) and Accredited International Laboratories like Fluke.

AC–DC Current Transfer Standards Suitable for Use Below 1mA and up to 1MHz

Traceability for ac currents below 1mA is needed to calibrate calibrators and multimeters at frequencies up to at least 100 kHz. Since the sensitivity of thermal convertors is not sufficient, only transfer standards using amplifiers are suitable. A newly designed combination of an amplifier and a shunt works at higher frequencies up to 1MHz.

International comparison of AC-DC current transfer standards

The measurements of the international comparison of ac-dc current transfer standards identified as EURAMET.EM-K12 started in June 2012 and were completed in December 2014. Twenty NMIs in the EURAMET region and one NMI in the AFRIMET region took part: BEV (Austria), CMI (Czech Republic), PTB (Germany), METAS (Switzerland), JV (Norway), UME (Turkey), GUM (Poland), IPQ (Portugal), CEM (Spain), INRIM (Italy), SP (Sweden), DANIAmet-MI-Trescal (Denmark), BIM (Bulgaria), MKEH (Hungary), SIQ (Slovenia), LNE (France), NSAI NML (Ireland), VSL (The Netherlands), NPL (United Kingdom), Metrosert (Estonia), NIS (Egypt).The comparison was proposed to link the National Metrology Institutes organised in EURAMET to the key comparison CCEM-K12. The ac-dc current transfer difference of each travelling standard had been measured at its nominal current 10 mA and 5 A at the following frequencies: 10 Hz, 55 Hz, 1 kHz, 10 kHz, 20 kHz, 50 kHz, 100 kHz. The test points were selected to link the results with the equivalent CCEM Key Comparison (CCEM-K12), through five NMIs participating in both EURAMET and CCEM key comparisons (PTB, JV, NPL, SP and BEV). The report shows the degree of equivalence in the EURAMET region and also the degree of equivalence with the corresponding CCEM reference value.Main textTo reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Development of Thin-Film Multijunction Thermal Current Converters With Increased Rated Current

Thin-film multijunction thermal converters (MJTCs) with a heater fabricated on an AlN chip have been developed for ac–dc current transfer standards. The rated current of the MJTC can be increased due to the good thermal conductivity of the AlN substrate, which acted as a heat sink drawing away heat from the heater. The AlN chip was mounted on a polyimide foil with thermocouples of the MJTC produced separately. In the case of an MJTC with a heater resistance of 5 $\Omega$ , which has a bifilar heater pattern to reduce the thermoelectric effects, the nominal current is 200 mA. The observed current level dependence of the ac–dc current transfer differences from 50 to 200 mA for the 5- $\Omega$ MJTC was within 1 $\mu\hbox{V/V}$ at frequency from 1 to 100 kHz. Compared with a conventional thermal converter, the wide range of available input current and small current level dependence of the new MJTCs may reduce uncertainties of ac–dc current transfer standards.

New generation of AC-DC Current Transfer Standards at Inmetro

New generation of AC-DC Current Transfer Standards at Inmetro

Final report on key comparison CCEM-K12: AC–DC current transferstandards

The circulation of the travelling standards in the CIPM key comparison CCEM-K12 of AC–DC current transfer difference began in March 2005 and was completed in April 2007. The travelling standards were lost on their way from the last participant to the pilot laboratory. Since, prior to their disappearance, the travelling standards exhibited exceptional stability, the CCEM Working Group on Low-Frequency Quantities decided in June 2008 to accept the results of the comparison as valid without the final measurement by the pilot laboratory.The AC–DC transfer differences of the travelling standards have been measured at 10 mA and 5 A, and at the frequencies 10 Hz, 55 Hz, 1 kHz, 10 kHz, 20 kHz, 50 kHz and 100 kHz. The key comparison reference values were calculated as the weighted means of the results of the National Metrology Institutes (NMIs) with independent realizations of primary standards and low reported uncertainties. The degrees of equivalence relative to the key comparison reference values, as well as between pairs of NMIs, have been determined for the measurement points and show very good agreement. All but three of the calculated degrees of equivalence relative to the key comparison reference values are within the limits of the expanded uncertainties.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

International Comparison of AC-DC Current Transfer Standards at Frequencies from 200 kHz to 1 MHz

This paper presents an international comparison of ac-dc current transfer measurements at 10 mA and frequencies up to 1 MHz between four national metrology institutes: NMIA (Australia), PTB (German...

Calibration of AC-DC Current Transfer Standards from 10 mA to 100 A Using a Step-Up Procedure

Recent developments have resulted in new planar multijunction thermal converters fabricated on quartz substrates, which are now used as primary calculable ac-dc current transfer standards with very...

Improved AC–DC Current Transfer Step-Up With New Current Shunts and Potential Driven Guarding

The ac-dc current transfer standards at PTB have been improved in frequency and current range up to 1 MHz and 1 A using a newly designed transconductance amplifier. Up to 100 kHz and 10 A, the uncertainties could be dramatically reduced. Starting from the calculable quartz planar multifunction thermal converter at 30 mA, for currents up to 10 A, new shunts with small frequency and current level dependence and an improved measurement set-up are used

Quartz Planar Multijunction Thermal Converter as a New AC–DC Current Transfer Standard Up to 1 MHz

The new generation of PMJTCs on quartz membranes and on quartz crystal chips developed at the PTB results in new ac-dc current transfer standards for the current of 10 mA and the frequency range from 10 kHz to 1 MHz, accompanied with small uncertainties. For a PMJTC with a heater resistance of 240 Omega the uncertainties for frequencies up to 100 kHz are smaller than 1 muA/A and up to 1 MHz they increase to 5 muA/A (k=1). A model for the PMJTC has been developed which allows calculating the ac-dc current transfer difference as well as the attributed uncertainties. The agreement of the simulation and the measurement were tested for high heater resistances of 700 Omega and 240 Omega, for which quite large ac-dc differences are calculated. The good agreement validates the model

AC-DC current transfer step-up and step-down calibration and uncertainty calculation

New AC-DC current transfer standards are built for the current range from 0.3 mA to 20 A and the frequency range from 10 Hz to 100 kHz. A three-dimensional PTB-multijunction thermal converter (MJTC) with a heater resistance of 27 /spl Omega/ is the basic standard for the AC-DC current transfer at currents from 20 to 50 mA. At lower currents, planar MJTCs (PMJTCs) with heater resistances from 90 to 960 /spl Omega/ are used in a step-down procedure. Coaxial current shunts in parallel with PMJTCs extend the current range up to 20 A. The standard measurement uncertainties are in the range from 0.2 /spl mu/A/A at 25 mA and 1 kHz to 50 /spl mu/A/A at 20 A and 100 kHz. The high sensitivity of the PMJTC allows bigger steps in the step-up calibration and some smaller steps between these steps. Calibration of all these steps leads to an overdetermined system to check for the validity of the assumptions made in the step-up procedure. This results in reduced uncertainties at the different current levels compared to the old method.

BCR intercomparison of AC-DC current transfer standards

The established national standards for ac-dc current transfer and the respective measurement set-ups of Denmark, France, Germany, Italy, Sweden, and The Netherlands were intercompared in the current range from 10 mA to 20 A and in the frequency range from 10 Hz to 100 kHz. An agreement within 10 ppm to 30 ppm was obtained up to 100 mA, degrading to 100 ppm at 1 A (100 kHz) and 70 ppm at 10 A (20 kHz) and 20 A (5 kHz). >

High precision automated measuring system for AC-DC current transfer standards

An automated measuring system for AC-DC current transfer standards were developed at the Swedish National Testing and Research Institute (SP). The use of a guard makes intercomparisons with ppm precision possible at frequencies up to 100 kHz. Two multijunction thermal converters are used for evaluating the uncertainty of the system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>