The KCDB - the BIPM key comparison database – supports the CIPM MRA. The KCDB contains information on the internationally recognized Calibration and Measurement Capabilities (CMCs) for services available from the participating institutes, and the key and supplementary comparisons supporting these CMCs.

All data listed in the KCDB have been reviewed and approved within the CIPM Mutual Recognition Arrangement
**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 *D _{i}* and expanded uncertainty

Click on the graph to get a closer view and the acronyms of the laboratories

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 *D _{i}* and expanded uncertainty

Click on the graph to get a closer view and the acronyms of the laboratories

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 *D _{i}* and expanded uncertainty

**Participants in CCEM-K8**

* indicate the laboratories which did not participate in the computation of the

CCEM-K8 key comparison reference value

**Participants in EUROMET.EM-K8**

** indicate the laboratories which did not participate in the computation of the EUROMET.EM-K8 reference value

**Participant in CCEM-K8.1**

**Participant in EUROMET.EM-K8.1**

The dates of measurement are available from Laboratory Individual Meaurements.

**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 *D _{i}* and expanded uncertainty

**Participants in CCEM-K8**

* indicates the laboratories which did not participate in the computation of the

CCEM-K8 key comparison reference value

**Participants in EUROMET.EM-K8**

** indicates the laboratories which did not participate in the computation of the EUROMET.EM-K8 reference value

**Participant in CCEM-K8.1**

**Participant in EUROMET.EM-K8.1**

The dates of measurement are available from Laboratory Individual Meaurements.

CCEM-K8.1

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.
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, INRIMItaly |

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" :

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

**Key comparison CCEM-K8**

The key comparison reference value, , is the arithmetic mean of the differences _{R}_{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}d_{0,IEN}. The standard uncertainty, u(, associated with _{R}) is the standard deviation of the mean._{R} |

** _{R} = -0.048x10^{-6} **with standard uncertainty of

The degree of equivalence of each laboratory with respect to the reference value is given by a pair of terms: , and the corresponding expanded uncertainty D = (_{i} - _{i}_{R}), 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 U_{i}. U_{i} |

**Key comparison EUROMET.EM-K8**

The reference value of EUROMET.EM-K8, , is the arithmetic mean of the differences _{R-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)._{i-EUR},The mean relative deviation of the ratio from nominal is given by the sum + _{R-EUR}. The standard uncertainty associated with d_{0,IEN-EUR} is the standard deviation of the mean._{R-EUR} |

** _{R-EUR} = -0.097x10^{-6} **with standard uncertainty of

The degree of equivalence of each laboratory with respect to the reference value is given by a pair of terms: , and the corresponding expanded uncertainty D_{i-EUR} = (_{i-EUR} - _{R-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 U_{i-EUR}. U_{i-EUR} |

**Linking EUROMET.EM-K8 to CCEM.EM-K8**

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:** D_{i} = D_{i-EUR}** and

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 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. D_{i} |

**Linking CCEM-K8.1 to CCEM-K8**

The degree of equivalence i with respect to the key comparison reference value , is given by the estimated difference _{R}( that the laboratory would have obtained if it had directly participated in comparison CCEM-K8, and by the corresponding 95% expanded uncertainty _{i} - _{R}). U_{i}The link to CCEM-K8 is given by IEN, who was the pilot laboratory in both comparisons, with: = (D_{i})_{i} - _{IEN}_{CCEM-K8.1} + ()_{IEN} - _{R}_{CCEM-K8}= (_{ }_{i}_{-K8.1 }-_{ }_{IEN-K8.1}) + D_{IEN} = (u_{i}+ u^{2}_{G,i-K8.1} + u^{2}_{transfer}(u^{2}_{R}))^{1/2},where represents the standard uncertainty of the link to CCEM-K8, evaluated tou_{transfer} 0.08x10. The degrees of freedom are taken into account in the calculation of^{-6}. U_{i} |

**Linking EUROMET.EM-K8.1 to CCEM-K8**

**
**

The link between EUROMET.EM-K8.1 and CCEM-K8 is computed in the same way, with .U_{i} |

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 D_{i}_{ }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 and the global standard uncertainty of the other laboratory. u_{transfer} |

**CCEM-K8, EUROMET.EM-K8, CCEM-K8.1 and EUROMET.EM-K8.1**

MEASURAND : DC voltage ratio 100 V / 10 V

NOMINAL VALUE : 10

**Key comparison CCEM-K8**

The key comparison reference value, , is the arithmetic mean of the differences _{R}_{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}d_{0,IEN}. The standard uncertainty, u(, associated with _{R}) is the standard deviation of the mean._{R} |

** _{R} = -0.050x10^{-6} **with standard uncertainty of

The degree of equivalence of each laboratory with respect to the reference value is given by a pair of terms: , and the corresponding expanded uncertainty D = (_{i} - _{i}_{R}), 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 U_{i}. U_{i} |

**Key comparison EUROMET.EM-K8**

The reference value of EUROMET.EM-K8, , is the weighted mean of the differences _{R-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)._{i-EUR},The mean relative deviation of the ratio from nominal is given by the sum + _{R-EUR}. d_{0,IEN-EUR}The standard uncertainty associated with is the weighted standard uncertainty._{R-EUR} |

** _{R-EUR} = -0.039x10^{-6} **with standard uncertainty of

The degree of equivalence of each laboratory with respect to the reference value is given by a pair of terms: , and the corresponding expanded uncertainty D_{i-EUR} = (_{i-EUR} - _{R-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 U_{i-EUR}. U_{i-EUR} |

**Linking EUROMET.EM-K8 to CCEM.EM-K8**

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: ** D_{i} = D_{i}_{-EUR} **and

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 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. D_{i} |

**Linking CCEM-K8.1 to CCEM-K8**

The degree of equivalence i with respect to the key comparison reference value , is given by the estimated difference _{R}( that the laboratory would have obtained if it had directly participated in comparison CCEM-K8, and by the corresponding 95% expanded uncertainty _{i} - _{R}). U_{i}The link to CCEM-K8 is given by IEN, who was the pilot laboratory in both comparisons. It is given by: = (D_{i})_{i} - _{IEN}_{CCEM-K8.1} + ()_{IEN} - _{R}_{CCEM-K8}_{ }= (-K8.1 - _{i}_{IEN-K8.1}) + D_{IEN} = (u_{i}+ u^{2}_{G,i-K8.1} + u^{2}_{transfer}(u^{2}_{R}))^{1/2},where represents the standard uncertainty of the link to CCEM-K8, evaluated to u_{transfer}. The degrees of freedom are taken into account in the calculation ofu_{transfer} = 0.12x10^{-6}. U_{i} |

**Linking EUROMET.EM-K8.1 to CCEM-K8**

The link between EUROMET.EM-K8.1 and CCEM-K8 is computed in the same way, with .U_{i} |

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 D_{i}_{ }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 and the global standard uncertainty of the other laboratory. u_{transfer} |

**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

** d_{0,i}**: fractional difference from nominal value of ratio

The fractional differences

Note: the additional indexes "** _{-K8.1}**", "

**Key comparison CCEM-K8****TRAVELLING STANDARD : voltage divider Datron 4902S, s/n 20335**

**Key comparison EUROMET.EM-K8**TRAVELLING STANDARD : voltage divider Datron 4902S, s/n 12422

- Key comparison CCEM-K8.1

TRAVELLING STANDARD : voltage divider Datron 4902S, s/n 20335

- Key comparison EUROMET.EM-K8.1

TRAVELLING STANDARD : voltage divider Datron 4902S, s/n 20335

**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

** d_{0,i}**: fractional difference from nominal value of ratio

The fractional differences

Note : the additional indexes "** _{-K8.1}**", "

- Key comparison CCEM-K8

TRAVELLING STANDARD : voltage divider Datron 4902S, s/n 20335

**Key comparison EUROMET.EM-K8**TRAVELLING STANDARD : voltage divider Datron 4902S, s/n 12422

**Key comparison CCEM-K8.1****TRAVELLING STANDARD : voltage divider Datron 4902S, s/n 20335**

- Key comparison EUROMET.EM-K8.1

TRAVELLING STANDARD : voltage divider Datron 4902S, s/n 20335