SIM Comparison of AC-DC Current Transfer Difference, SIM.EM-K12
Lucas Di Lillo1, Eliana Yasuda1, Thomas Lipe2, Sara Campos3, Alfredo Spaggiari4, Daniel Slomovitz4, Carlos Faverio4, Piotr Filipski5, Renata Vasconcellos6, Gean Geronymo6, Renato Afonso Jr6, Mamdouh
Halawa7 1INTI (ldili@inti.gob.ar), 2NIST, 3CENAM, 4UTE, 5NRC, 6INMETRO, 7NIS
ABSTRACT — A key comparison of the AC-DC current transfer difference has been carried out by the Inter-American Metrology System (SIM) Regional Metrology Organization (RMO). Its purpose was to establish an equivalence of AC-DC current transfer difference at 10 mA and 5 A between the national metrology institutes (NMIs), in support of the International Committee for Weights and Measures (CIPM) Mutual Recognition Agreement (MRA). The comparison artifact was a Planar Multijunction Thermal Converter (PMJTC) at 10 mA and a 5 A shunt at 5 A measurements. Six SIM NMIs participated in the comparison as well as NIS, National Institute of Standard of Egypt. Results linking the SIM.EM-K12 to CCEM-K12 show agreement of SIM NMIs to other RMOs.
Index Terms — Measurement, measurement standards, measurement techniques, AC-DC, current transfer difference, measurement uncertainty, precision measurements, uncertainty.
I. INTRODUCTION
In the Inter-American Metrology System (SIM) there are several National Metrology Institutes (NMIs). From them only three participated in the CCEM key Comparisons of the ac-dc current transfer difference CCEM-K12. In accordance with the CIPM-MRA objectives, the NMIs establish an equivalence between their national measurement standards by performing regional comparisons. The SIM.EM-K12 comparison was proposed to assess the measurement capabilities of the remaining SIM NMIs, in the ac-dc current transfer difference. The test points were selected to facilitate link of the results of this comparison with the equivalent CCEM K12 Key Comparison, through the three NMIs participating in both. INTI, Argentina provided the travelling standard, and piloted and coordinated the comparison. It was agreed that the comparison reference values were to be based on the results provided by the participating laboratories with participation in the CCEM-K12 key comparison.
II. TRAVELING STANDARD, MEASUREMENT POINTS AND
PARTICIPANTS
The travelling standard for current of 10 mA was a Planar Multijunction Thermal Converter (PMJTC), identified as “PMJTC-90-2”. The travelling standard for current of 5 A comprises the same 10 mA/1V PNJTC as well as a 0.2 Ω coaxial shunt, identified as “SHUNT 5 A”.
The ac-dc difference of each travelling standard was to be measured at its nominal current and the following frequencies: 10 Hz, 55 Hz, 1 kHz, 10 kHz, 20 kHz, 50 kHz and 100 kHz.
The traveling standards were measured at INTI at the beginning and the end of the comparison schedule. The traveling standards travelled regionally between participant laboratories, with two intermediate stops at INTI.
Table I shows the participants of the comparison
Table I. SIM.EM-K12 Participants
Country
NMI
Argentina
INTI
Uruguay
UTE
Canada
NRC
USA
NIST
Mexico
CENAM
Brazil
INMETRO
Egypt
NIS
III. METHOD OF COMPUTATION OF THE CRV
The comparison reference values (CRV) for each of the measured points was calculated as the weighted mean of the reported values from laboratories in SIM who have taken part in the CCEM-K12 key comparison and whose reported values had been taken in consideration to calculate the reference values in such comparison (i.e. NRC, NIST and INTI)
The reference value was determined as:
3δ
i
∑ CRV
=
i =1 3
U2 δi
1
∑i=1
U2 δi
(1)
where
Uδi is
the
expanded
uncertainty
associated
with
δ i
values, used to calculate the reference value, and reported with
a confidence level of 95 %.
The expanded uncertainty of the reference value was
calculated,
UCRV =
1
∑3
1
U2
i =1
δi
(2)
978-1-4799-2479-0/14/$31.00 ©2014 IEEE
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IV. REPORTED RESULTS
The reported results for each participant at 10 mA and 5 A are shown in Tables II and III.
Table II. Reported results at 10 mA
Measured AC-DC difference δi and expanded uncertainty Ui in µA/A
10 Hz
55 Hz
1 kHz 10 kHz 20 kHz 50 kHz 100 kHz
δi
Ui
δi
Ui
δi
Ui
δi
Ui
δi
Ui
δi
Ui
δi
Ui
INTI
8,0 6,0 0,6 4,0 0,1 3,0 0,1 3,0 0,4 3,0 1,0 10,0 2,0 20,0
NRC
8,3 1,6 0,3 1,0 0,0 0,9 0,2 1,8 0,1 1,9 0,9 1,9 3,2 2,0
INTI 10,2 6,0 0,6 4,0 0,0 3,0 1,3 3,0 -0,7 3,0 3,3 10,0 0,3 20,0
UTE
---- ---- -4,0 12,0 -4,0 12,0 -3,0 14,0 ---- ---- ---- ---- ---- ----
INMETRO 8,2 3,3 0,5 3,3 0,0 3,2 -0,1 3,3 -0,1 3,3 -0,2 3,2 0,8 3,2
CENAM ---- ----- 0,6 22,0 0,4 22,0 0,5 22,0 1,1 22,0 3,8 22,0 1,7 24,0
NIST 9,0 9,0 0,0 6,0 -1,0 4,0 1,0 4,0 2,0 4,0 6,0 7,0 11,0 10,0
INTI 10,1 6,0 0,7 4,0 -0,2 3,0 1,2 3,0 1,7 3,0 1,5 10,0 0,8 20,0
NIS
2,8 3,1 -0,9 2,7 -1,0 5,5 -2,7 6,4 ---- ---- ---- ---- ---- ----
INTI
9,8 6,0 -0,2 4,0 -0,2 3,0 -0,1 3,0 -0,3 3,0 1,5 10,0 4,1 20,0
were calculated based on approach described in [1] by using the measurement results from the linking laboratories. Tables VI and VII list the degree of equivalence (DoE) of the four other NMIs with respect to the CCEM-K12 [2] key comparison reference value (KCRV) and the corresponding expanded uncertainties of the DoE´s. Units are in tables.
Table VI. DoE of all NMIs with respect to the KCRV at
10 mA
Degree of equivalence DoE w ith the KCRV and expanded uncertainty Ui at 10 mA in µA/A 10 Hz 55 Hz 1 kHz 10 kHz 20 kHz 50 kHz 100 kHz
DoE Ui DoE Ui DoE Ui DoE Ui DoE Ui DoE Ui DoE Ui
UTE
---- ---- -4,2 12,1 -4,1 12,0 -3,4 14,2 ---- ---- ---- ---- ---- ----
INMETRO -0,2 3,9 0,3 3,5 -0,1 3,4 -0,5 3,9 -0,5 4,0 -1,1 4,0 -2,2 4,0
CENAM ---- ---- 0,4 22,0 -0,1 22,0 0,1 22,1 0,7 22,1 2,9 22,1 -1,3 24,1
NIS -5,6 3,8 -1,1 2,9 -1,1 5,6 -3,1 6,7 ---- ---- ---- ---- ---- ----
INTI NRC INTI UTE INMETRO CENAM NIST INTI NIS INTI
Table III. Reported results at 5 A
Measured AC-DC difference δi and expanded uncertainty Ui in µA/A
10 Hz
δi
Ui
55 Hz
δi
Ui
1 kHz
δi
Ui
10 kHz
δi
Ui
20 kHz
δi
Ui
50 kHz
δi
Ui
100 kHz
δi
Ui
-4,8 8,0 0,0 5,0 2,0 5,0 -0,2 7,0 2,6 10,0 9,8 13,0 29,4 22,0
-4,9 14,7 -1,2 14,0 -0,9 14,0 1,6 14,7 -1,3 14,6 6,8 19,6 14,0 30,7
-5,2 8,0 -1,0 5,0 2,4 5,0 -1,1 7,0 1,7 10,0 9,5 13,0 32,7 22,0
--- --- 1,0 24,0 2,0 24,0 14,0 30,0 ---- ---- ---- ---- ---- ----
-0,4 9,7 -0,5 9,0 0,2 5,9 0,2 6,9 2,0 8,0 9,9 10,3 19,0 16,0
--- --- -2,0 42,0 0,0 36,0 17,0 40,0 ---- ---- ---- --- ---- ----
0,0 19,0 -2,0 18,0 2,0 17,0 2,0 17,0 0,0 21,0 6,0 27,0 -4,0 33,0
-5,7 8,0 0,6 5,0 2,7 5,0 -0,1 7,0 1,1 10,0 6,5 13,0 28,4 22,0
--- --- -0,4 16,8 20,0 17,3 288,0 20,0 --- --- --- --- --- ---
-5,7 8,0 -0,3 5,0 1,1 5,0 -1,8 7,0 2,1 10,0 10,0 13,0 32,2 22,0
Table IV. DoE of all NMIs with respect to the CRV at
INTI NRC INTI UTE INMETRO CENAM NIST INTI NIS INTI
10 mA
Degree of equivalence DoE and expanded uncertainty Ui at 10 mA in µA/A
10 Hz
55 Hz
1 kHz
10 kHz
20 kHz
50 kHz
100 kHz
DoE Ui DoE Ui DoE Ui DoE Ui DoE Ui DoE Ui DoE Ui
-0,4 5,8 0,3 3,9 0,1 2,9 -0,3 2,6 0,0 2,6 -0,3 9,8 -1,5 19,9
-0,1 0,5 0,0 0,3 0,0 0,3 -0,2 1,1 -0,3 1,2 -0,4 0,6 -0,3 0,4
1,8 5,8 0,3 3,9 0,1 2,9 0,9 2,6 -1,1 2,6 2,0 9,8 -3,2 19,9
---- ---- -4,3 12,0 -4,0 12,0 -3,4 14,1 ---- ---- ---- ---- ---- ----
-0,2 3,6 0,2 3,4 0,0 3,3 -0,5 3,6 -0,5 3,6 -1,5 3,7 -2,7 3,7
---- ---- 0,3 22,0 0,0 22,0 0,1 22,0 0,7 22,1 2,5 22,1 -1,8 24,1
0,6 8,9 -0,3 5,9 -1,0 3,9 0,6 3,7 1,6 3,7 4,7 6,8 7,5 9,8
1,7 5,8 0,4 3,9 -0,2 2,9 0,8 2,6 1,3 2,6 0,2 9,8 -2,7 19,9
-5,6 3,5 -1,2 2,9 -1,0 5,6 -3,1 6,6 ---- ---- ---- ---- ---- ----
1,4 5,8 -0,5 3,9 -0,2 2,9 -0,5 2,6 -0,7 2,6 0,2 9,8 0,6 19,9
Table VII. DoE of all NMIs with respect to the KCRV at
5A
Degree of equivalence DoE with the KCRV and expanded uncertainty Ui at 5 A in µA/A
10 Hz
55 Hz
1 kHz
10 kHz
20 kHz 50 kHz 100 kHz
DoE Ui DoE Ui DoE Ui
DoE
UTE ---- ---- 1,8 25,3 -2,2 24,9 14,8
INMETRO 2,8 14,1 0,3 12,0 -4,0 8,9 1,0
CENAM ---- ---- -1,2 42,7 -4,2 36,6 17,8
NIS ---- ---- 0,4 18,6 15,8 18,5 288,8
Ui 31,3 11,4 41,0 22,0
DoE Ui DoE Ui DoE Ui ---- ---- ---- ---- ---- ---0,9 13,9 -0,1 18,9 9,7 29,9 ---- ---- ---- ---- ---- ------- ---- ---- ---- ---- ----
VI. CONCLUSION The AC-DC transfer differences of the travelling standards have been measured at 10 mA and 5 A at frequencies 10 Hz, 55 Hz, 1 kHz, 10 kHz, 20 kHz, 50 kHz and 100 kHz. The comparison reference values were calculated as the weighted mean of the results of the NMIs with independent realizations of their primary standards and low reported uncertainties. The degrees of equivalence with the CRV and the degree of equivalence with the KCRV of CCEM-K12 show very good agreement. In the case of NIS, the NMI is going to evaluate the results at 5 A 1 kHz and 5 A 10 kHz and will perform a bilateral comparison in these points at a later date.
AKNOWLEDGEMENT
Table V. DoE of all NMIs with respect to the CRV at 5 A
Degree of equivalence DoE and expanded uncertainty U at 10 mA in µA/A
10 Hz
55 Hz
1 kHz
10 kHz
20 kHz
50 kHz
100 kHz
Di
Ui
Di
Ui
Di
Ui
Di
Ui
Di
Ui
Di
Ui
Di
Ui
INTI -0,2 4,5 0,4 2,1 0,3 2,1 -0,2 3,7 1,8 6,4 1,9 8,2 10,9 15,4
NRC -0,3 13,1 -0,8 13,2 -2,6 13,2 1,7 13,5 -2,0 12,4 -1,2 16,8 -4,4 26,4
INTI -0,6 4,5 -0,6 2,1 0,7 2,1 -1,0 3,7 1,0 6,4 1,5 8,2 14,3 15,4
UTE
---- ---- 1,4 23,6 0,3 23,6 14,1 29,4 ---- ---- ---- ---- ---- ----
INMETRO 4,2 7,1 -0,1 7,8 -1,5 3,8 0,3 3,5 1,3 2,2 1,9 2,2 0,6 3,0
CENAM ---- ---- -1,6 41,8 -1,7 35,7 17,1 39,6 ---- ---- ---- ---- ---- ----
NIST 4,6 17,8 -1,6 17,4 0,3 16,4 2,1 15,9 -0,7 19,5 -2,0 25,1 -22,4 29,0
INTI -1,1 4,5 1,0 2,1 1,0 2,1 0,0 3,7 0,4 6,4 -1,5 8,2 9,9 15,4
NIS
---- ---- 0,0 16,2 18,3 16,7 288,1 19,1 ---- ---- ---- ---- ---- ----
INTI -1,1 4,5 0,1 2,1 -0,6 2,1 -1,7 3,7 1,4 6,4 2,0 8,2 13,8 15,4
V. LINKAGE WITH CCEM-K12
INTI, NRC and NIST participated in the CCEM-K12 comparison. The results of statistically linking the other SIM.EM.K-12 participants to the CCEM-K12 participants
Acknowledgment is due to Dr. Gregory Kyriazis from INMETRO, Brazil and Ing. Sara Campos from CENAM, Mexico as members of the supporting group of this comparison. They are also acknowledged for kindly encouraging the participant laboratories to meet the scheduled time of this comparison.
REFERENCES
[1] F. Delahaye and T. J. Witt, “Linking the Results of Key Comparison CCEM-K4 with the 10 pF Results of EUROEMT Project 345”, Metrologia 39 (Tech. Suppl.) 01005, 2002.
[2] I. Budovsky, “Key International Comparison of AC-DC Current Transfer Standards CCEM-K12”, www.bipm.org.
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