CCEM.EM-K8, EUROMET.EM-K8, CCEM-K8.1 and EUROMET.EM-K8.1
MEASURAND : DC voltage ratio 1000 V / 10 V
NOMINAL VALUE : 100
Degrees of equivalence Di and expanded uncertainty Ui at a 95% level of confidence in 10-6
Click on the graph to get a closer view and the acronyms of the laboratories
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Red diamonds: participants in CCEM-K8
Green triangles: participants in EUROMET.EM-K8
Black square: participant in CCEM-K8.1
Blue circles: participants in EUROMET.EM-K8.1
The dates of measurement are available from Laboratory Individual Meaurements.
The graph of equivalence can be printed out from page 8 of the .PDF file Summary Results.
CCEM.EM-K8, EUROMET.EM-K8, CCEM-K8.1 and EUROMET.EM-K8.1
MEASURAND : DC voltage ratio 100 V / 10 V
NOMINAL VALUE : 10
Degrees of equivalence Di and expanded uncertainty Ui at a 95% level of confidence in 10-6
Click on the graph to get a closer view and the acronyms of the laboratories
_gd.gif)
Red diamonds: participants in CCEM-K8
Green triangles: participants in EUROMET.EM-K8
Black square: participant in CCEM-K8.1
Blue circles: participants in EUROMET.EM-K8.1
The dates of measurement are available from Laboratory Individual Meaurements.
The graph of equivalence can be printed out from page 16 of the .PDF file Summary Results.
CCEM-K8, EUROMET.EM-K8, CCEM-K8.1 and EUROMET.EM-K8.1
MEASURAND : DC voltage ratio 1000 V / 10 V
NOMINAL VALUE : 100
Degrees of equivalence Di and expanded uncertainty Ui at a 95% level of confidence:
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* indicate the laboratories which did not participate in the computation of the
CCEM-K8 key comparison reference value
The dates of measurement are available from Laboratory Individual Meaurements.
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** indicate the laboratories which did not participate in the computation of the EUROMET.EM-K8 reference value
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CCEM-K8, EUROMET.EM-K8, CCEM-K8.1 and EUROMET.EM-K8.1
MEASURAND : DC voltage ratio 100 V / 10 V
NOMINAL VALUE : 10
Degrees of equivalence Di and expanded uncertainty Ui at a 95% level of confidence:
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* indicates the laboratories which did not participate in the computation of the
CCEM-K8 key comparison reference value
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** indicates the laboratories which did not participate in the computation of the EUROMET.EM-K8 reference value
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The dates of measurement are available from Laboratory Individual Meaurements.
| Metrology area, Sub-field | Electricity and Magnetism, DC Voltage and Current |
| Description | Comparison of DC voltage ratios |
| Time of measurements | 2002 - 2003 |
| Status | Approved for equivalence |
| Final Reports of the comparisons | |
| Measurand | DC voltage ratio: 1000 V / 10 V and 100 V / 10 V |
| Transfer device | Datron 4902S standard divider, s/n 20335 |
| Comparison type | Key Comparison |
| Consultative Committee | CCEM (Consultative Committee for Electricity and Magnetism) |
| Conducted by | CCEM (Consultative Committee for Electricity and Magnetism) |
| Comments | This comparison is a follow-up of comparison CCEM-K8. EUROMET.EM-K8 results, CCEM-K8.1 results, and EUROMET.EM-K8.1 results are linked to those of CCEM-K8. CCEM-K8 results were published on 16 January 2003. Two DC voltage ratios, 1000 V / 10 V (nominal value: 100) and 100 V / 10 V (nominal value: 10) are measured using Datron standard dividers as travelling standards. |
| Pilot institute |
IEN
Istituto Elettrotecnico Nazionale Galileo Ferraris; from 1st January 2006: Istituto Nazionale di Ricerca Metrologica, INRIM Italy |
| Contact person | G. Marullo Reedtz +39 011 3919 421 |
This page proposes print-out on A4 paper (portrait) of the comparison details (best printed out using a black and white printer).
Please, select items to be printed out, then click on "OK" :
CCEM-K8, EUROMET.EM-K8, CCEM-K8.1 and EUROMET.EM-K8.1
MEASURAND : DC voltage ratio 1000 V / 10 V
NOMINAL VALUE : 100
The key comparison reference value,  R, is the arithmetic mean of the differences i, obtained from twelve participants. (Statistical tests indicate that there is a high probability that the result of each of the other three participants does not belong to the same statistical distribution as the other twelve).The mean relative deviation of the ratio from nominal is given by the sum R + d0,IEN. The standard uncertainty, u(R), associated with R is the standard deviation of the mean. |
R = -0.048x10-6 with standard uncertainty of 0.062x10-6
and 11 degrees of freedom
The degree of equivalence of each laboratory with respect to the reference value is given by a pair of terms:  Di = (i - R), and the corresponding expanded uncertainty Ui, assessed for a level of confidence of 95%. For the 12 laboratories contributing to the definition of the reference value, the correlation with the reference value is taken into account in the computation of Ui. |
| The reference value of EUROMET.EM-K8, R-EUR, is the arithmetic mean of the differences i-EUR, obtained from seventeen participants. (Statistical tests indicate that there is a high probability that the result of each of the two other participants does not belong to the same statistical distribution as the other seventeen). The mean relative deviation of the ratio from nominal is given by the sum R-EUR + d0,IEN-EUR. The standard uncertainty associated with R-EUR is the standard deviation of the mean. |
R-EUR = -0.097x10-6 with standard uncertainty of 0.103x10-6
and 16 degrees of freedom
| The degree of equivalence of each laboratory with respect to the reference value is given by a pair of terms: Di-EUR = (i-EUR - R-EUR), and the corresponding expanded uncertainty Ui-EUR, assessed for a level of confidence of 95%. For the 17 laboratories contributing to the definition of the reference value, the correlation with the reference value is taken into account in the computation of Ui-EUR. |
In a measurement of voltage ratio, no national standard is involved. Therefore any participant in EUROMET.EM-K8 and CCEM-K8 comparisons can be considered equally able, in principle, to perform an unbiased measurement of the travelling standard. Since the number of participants in each comparison is significant and different methods of measurement were used, it is unlikely that the corresponding comparison reference values are affected by systematic errors. Therefore they are equivalent and the degrees of equivalence obtained from the EUROMET.EM-K8 comparison are assumed to be the same as if the participants had taken part in the CCEM-K8 comparison:
Di = Di-EUR and Ui = Ui-EUR for the participants in EUROMET.EM-K8 comparison.
The Linkage Report gives a verification of this assumption based on the results of the common participants in both comparisons.
| Because voltage ratios, and not national standards, were the object of these comparisons, the CCEM has decided not to publish the table of the bilateral degrees of equivalence, which are not really significant in the present case. They can, however, be calculated by the difference of the Di values, with corresponding 95% uncertainty given, within an approximation of about 5% or better, by twice the root-sum-square of the global standard uncertainties of the two laboratories involved. |
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The degree of equivalence Di of laboratory i with respect to the key comparison reference value |
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The link between EUROMET.EM-K8.1 and CCEM-K8 is computed in the same way, with utransfer = 0.08x10-6. The degrees of freedom have negligible influence in the calculation of Ui. |
| The bilateral degrees of equivalence of laboratory i having participated in CCEM-K8.1 or EUROMET.EM-K8.1, with respect to any other laboratory participating in CCEM-K8 or EUROMET.EM-K8, can be calculated by the difference of the Di values of the two laboratories, with corresponding 95% uncertainty given, within an approximation of 5% or better, by twice the root-sum-square of three terms: the global standard uncertainty of laboratory i, the transfer standard uncertainty utransfer and the global standard uncertainty of the other laboratory. |
CCEM-K8, EUROMET.EM-K8, CCEM-K8.1 and EUROMET.EM-K8.1
MEASURAND : DC voltage ratio 100 V / 10 V
NOMINAL VALUE : 10
The key comparison reference value,  R, is the arithmetic mean of the differences i, obtained from thirteen participants. (Statistical tests indicate that there is a high probability that the result of each of the other two participants does not belong to the same statistical distribution as the other thirteen).The mean relative deviation of the ratio from nominal is given by the sum R + d0,IEN. The standard uncertainty, u(R), associated with R is the standard deviation of the mean. |
R = -0.050x10-6 with standard uncertainty of 0.083x10-6
and 12 degrees of freedom
The degree of equivalence of each laboratory with respect to the reference value is given by a pair of terms:  Di = (i - R), and the corresponding expanded uncertainty Ui, assessed for a level of confidence of 95%. For the 13 laboratories contributing to the definition of the reference value, the correlation with the reference value is taken into account in the computation of Ui. |
| The reference value of EUROMET.EM-K8, R-EUR, is the weighted mean of the differences i-EUR, obtained from sixteen participants. (Statistical tests indicate that there is a high probability that the result of each of the three other participants does not belong to the same statistical distribution as the other sixteen). The mean relative deviation of the ratio from nominal is given by the sum R-EUR + d0,IEN-EUR. The standard uncertainty associated with R-EUR is the weighted standard uncertainty. |
R-EUR = -0.039x10-6 with standard uncertainty of 0.039x10-6
and 105 degrees of freedom
| The degree of equivalence of each laboratory with respect to the reference value is given by a pair of terms: Di-EUR = (i-EUR - R-EUR), and the corresponding expanded uncertainty Ui-EUR, assessed for a level of confidence of 95%. For the 16 laboratories contributing to the definition of the reference value, the correlation with the reference value is taken into account in the computation of Ui-EUR. |
In a measurement of voltage ratio, no national standard is involved. Therefore any participant in EUROMET.EM-K8 and CCEM-K8 comparisons can be considered equally able, in principle, to perform an unbiased measurement of the travelling standard. Since the number of participants in each comparison is significant and different methods of measurement were used, it is unlikely that the corresponding comparison reference values are affected by systematic errors. Therefore they are equivalent and the degrees of equivalence obtained from the EUROMET.EM-K8 comparison are assumed to be the same as if the participants had taken part in the CCEM-K8 comparison:
Di = Di-EUR and Ui = Ui-EUR for the participants in EUROMET.EM-K8 comparison.
The Linkage Report gives a verification of this assumption based on the results of the common participants in both comparisons.
| Because voltage ratios, and not national standards, were the object of these comparisons, the CCEM has decided not to publish the table of the bilateral degrees of equivalence, which are not really significant in the present case. They can, however, be calculated by the difference of the Di values, with corresponding 95% uncertainty given, within an approximation of about 10% or better, by twice the root-sum-square of the global standard uncertainties of the two laboratories involved. |
|
The degree of equivalence Di of laboratory i with respect to the key comparison reference value |
|
The link between EUROMET.EM-K8.1 and CCEM-K8 is computed in the same way, with utransfer = 0.12x10-6. The degrees of freedom have negligible influence in the calculation of Ui. |
| The bilateral degrees of equivalence of laboratory i having participated in CCEM-K8.1 or EUROMET.EM-K8.1, with respect to any other laboratory participating in CCEM-K8 or EUROMET.EM-K8, can be calculated by the difference of the Di values of the two laboratories, with corresponding 95% uncertainty given, within an approximation of 5% or better, by twice the root-sum-square of three terms: the global standard uncertainty of laboratory i, the transfer standard uncertainty utransfer and the global standard uncertainty of the other laboratory. |
CCEM-K8, EUROMET.EM-K8, CCEM-K8.1 and EUROMET.EM-K8.1
MEASURAND : DC voltage ratio 1000 V / 10 V
NOMINAL VALUE : 100
Pilot laboratory: IEN
d0,i: fractional difference from nominal value of ratio x0,i, measured by laboratory i and corrected to standard ambient conditions; it is given by: x0,i = 100 x (1 + d0,i)
The fractional differences d0,IEN assigned by IEN to the ratio are obtained by interpolation of the IEN measurement results to the measurement dates of the other laboratories. 
i = (d0,i - d0,IEN)
uG,i: global standard uncertainty of laboratory i
neff,i: number of effective degrees of freedom of laboratory i
Note: the additional indexes "-K8.1", "-EUR" and "-EUR-K8.1" are used for the CCEM-K8.1, EUROMET.EM-K8 and EUROMET.EM-K8.1 key comparisons.
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CCEM-K8, EUROMET.EM-K8, CCEM-K8.1 and EUROMET.EM-K8.1
MEASURAND : DC voltage ratio 100 V / 10 V
NOMINAL VALUE : 10
Pilot laboratory: IEN
d0,i: fractional difference from nominal value of ratio x0,i, measured by laboratory i and corrected to standard ambient conditions; it is given by: x0,i = 10 x (1 + d0,i)
The fractional differences d0,IEN assigned by IEN to the ratio are obtained by interpolation of the IEN measurement results to the measurement dates of the other laboratories. 
i = (d0,i - d0,IEN)
uG,i: global standard uncertainty of laboratory i
neff,i: number of effective degrees of freedom of laboratory i
Note : the additional indexes "-K8.1", "-EUR" and "-EUR-K8.1" are used for the CCEM-K8.1, EUROMET.EM-K8 and EUROMET.EM-K8.1 key comparisons.
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