Comparison
Comparison close
Results

CCEM-K10 and EUROMET.EM-K10

MEASURAND : Resistance
NOMINAL VALUE : 100 ohms

Degrees of equivalence Di and expanded uncertainty Ui (k = 2)

Click on the graph for a closer view

Red diamonds: participants in CCEM-K10
Green triangles: participants in EUROMET.EM-K10 only


Zoomed graph for CCEM-K10 participants only

Comparison
Comparison close
Results

CCEM-K10 and EUROMET.EM-K10

MEASURAND : Resistance
N
OMINAL VALUE : 100 ohms

Degrees of equivalence Di and expanded uncertainty Ui (k = 2)

In blue: linking laboratories
In green: participants in EUROMET.EM-K10 only

* Denotes laboratories that claim an uncertainty smaller than the transport uncertainty. For these laboratories the result reflects the limited knowledge on the behavior of the travelling standards and not the capability of the laboratory.
** Denotes that the result was obtained by a repeated measurement in October 2006.

Results are presented under A4 printable format in Summary Results (.PDF file).

Comparison
Comparison close
CC comparison
Linked comparison
CCEM-K10
Metrology area, Sub-field Electricity and Magnetism, Resistance
Description Comparison of resistance standards
Time of measurements 2001 - 2003
Status Approved for equivalence
Final Reports of the comparisons
Measurand Resistance: 100 ohms
Transfer device Resistors with 4 terminal connectors
Comparison type Key Comparison
Consultative Committee CCEM (Consultative Committee for Electricity and Magnetism)
Conducted by CCEM (Consultative Committee for Electricity and Magnetism)
Comments

 

 

Results published on 20 February 2007

EUROMET.EM-K10 results are linked to those of CCEM-K10

Resistance

 

 

Pilot institute PTB
Physikalisch-Technische Bundesanstalt
Germany
Contact person Bernd Schumacher
bernd.schumacher@ptb.de
+49 (0) 531 592 2122
First Name Last Name
wwww@ww.www +356719836 Institute 1 Institute 1 Khmelnitskiy
Pilot laboratory
PTB

Physikalisch-Technische Bundesanstalt, Germany, EURAMET

BIPM

Bureau International des Poids et Mesures, BIPM - International Organization, N/A

METAS

Federal Institute of Metrology, Switzerland, EURAMET

MIKES

VTT Technical Research Centre of Finland Ltd, Centre for Metrology/Mittatekniikan keskus, Finland, EURAMET

NIM

National Institute of Metrology, China, APMP

NIST

National Institute of Standards and Technology, United States, SIM

NMIA

National Measurement Institute, Australia, Australia, APMP

NMIJ AIST

National Metrology Institute of Japan, Japan, APMP

NRC

National Research Council, Canada, SIM

Comparison
Comparison close
Results

CCEM-K10 and EUROMET.EM-K10

MEASURAND : Resistance
NOMINAL VALUE : 100 ohms

PILOT LABORATORY : PTB

  • Key comparison CCEM-K10

The key comparison reference value, xR, is obtained from the weighted mean of the Di-comb’s: xR = -0.14 x 10-9.
Its associated uncertainty (k = 2) is UR = 4.57 x 10-9 (see on page 8 of the CCEM-K10 Final Report).

The degree of equivalence of laboratory i with respect to the key comparison reference value is given by a pair of terms: the offset Di = Di-comb - xR, and its expanded uncertainty (k = 2), Ui = (Ui-comb,T2 - UR2)1/2.

All uncertainties (except NMIA) are significantly greater than the laboratory’s claims due to the added transport uncertainty of the resistors. So these results are limited by the transportability of the resistors and not by the capability of the participants.

Therefore the degrees of equivalence between pairs of laboratories are not meaningful
.
  • Linking EUROMET.EM-K10 to CCEM-K10

The linking laboratories are MIKES, METAS, BIPM and PTB.
The linkage process is explained in Section 6.4 of the EUROMET Final Report.

The degree of equivalence of laboratory i, participant in EUROMET.EM-K10 only, with respect to the CCEM-K10 key comparison reference value is given by a pair of terms: the offset Di = Di EUR + xR EUR - xR, and its expanded uncertainty (k = 2),
Ui = (Ui EUR2 + ULink2)1/2, with xR EUR - xR = 3.30 10-9 and ULink = 9.80 10-9.
Comparison
Comparison close
Results

CCEM-K10 and EUROMET.EM-K10

  • Key comparison CCEM-K10

MEASURAND : Resistance
NOMINAL VALUE : 100 ohms

PILOT LABORATORY : PTB

xi : result of measurement carried out by laboratory i, expressed as the relative deviation from the nominal value R0 = 100 ohms, namely Ri = R0·(1 + xi) where Ri is the resistance measured by laboratory i. The xis are corrected to a nominal temperature of 23 °C and a nominal pressure of 1013.25 hPa.
ULabi : expanded uncertainty (k = 2) of xi

Four different transfer standards have been used.

Individual measurements are combined as follows:
Di-comb : combined mean of the travelling standards relative differences from a least-squares regression of the PTB values for each travelling standard
Ui-comb : expanded uncertainty (k = 2) of Di-comb
Ui-comb,T : expanded uncertainty (k = 2) of Di-comb, including an additional travel uncertainty estimated to 7 x 10-9

The calculation of the Di-comb’s and the Ui-comb’s is described in detail in Section 6 on page 7 of the CCEM-K10 Final Report.

  • Key comparison EUROMET.EM-K10

MEASURAND : Resistance
NOMINAL VALUE : 100 ohms

PILOT LABORATORY : PTB

Measurements were carried out using three sets of transfer standards in three loops in parallel. Corresponding results are reported in Tables 1 to 9 of Appendix A of the Final Report.
Measurement dates are given in Section 2 of the Final Report.

The PTB is the only common laboratory to all loops and is used to link them (see Section 6 of the Final Report). Results are then expressed in terms of Di-comb EUR, the combined measurement of laboratory i relative to the PTB, and Ui-comb EUR, the expanded uncertainty (k = 2) of Di-comb EUR taking into account the travel uncertainty. These values are available in Table 16 of the Final Report.

The EUROMET reference value, xR EUR, and its associated expanded uncertainty
(k = 2), UR EUR, are determined from the weighted mean of the Di-comb EUR with the Ui-comb EUR used as weights. In this calculation only one value is considered for the pilot laboratory, and to exclude possible correlation, only those laboratories having their own representation of the ohm, based on the QHE, are taken into consideration.
xR EUR = 4.0 10-9 and UR EUR = 6.0 10-9

Degrees of equivalence inside the EUROMET key comparison are deduced using the appropriate equations (see Section 6.3 of the Final Report). They are given by a pair of terms: Di EUR, the laboratory i offset relative to the EUROMET reference value, and the associated expanded uncertainty (k = 2), Ui EUR.

Italics: acronyms of laboratories whose results are not used for the calculation of the EUROMET reference value.
* Denotes laboratories that claim an uncertainty smaller than the transport uncertainty. For these laboratories the result reflects the limited knowledge on the behavior of the travelling standards and not the capability of the laboratory.
** Denotes that the result was obtained by a repeated measurement in October 2006.