About calibration laboratory
Metrology of high-voltage measurands
Terms and symbols
A B C
Third-party confirmation that formally sets out that a conformity assessment body has the competence to carry out certain conformity assessment tasks.
DIN EN ISO/IEC 17011
According to Regulation (EU) 765/2008, the accreditation system in Germany was changed on 1 January 2010. The
German Accreditation Body
(Deutsche Akkreditierungsstelle GmbH) carries out the accreditations.
Best measurement capability
The smallest measurement uncertainty that can be stated is the measurement uncertainty stated in the attachment of the accreditation certificate; this can be certified by an accredited calibration laboratory in the calibration certificate if required. A calibration laboratory cannot certify a smaller measurement uncertainty than the measurement uncertainty certified as the smallest measurement uncertainty that can be stated for relevant measuring ranges and measurands.
Bureau international des poids et mesures
International Bureau of Weights and Measures. The highest metrological institution worldwide; responsible for looking after the international standards of the SI system of units. For example, the JCGM working group is part of BIPM and manages the Guide to the Expression of Uncertainty in Measurement (GUM) and the International Vocabulary of Metrology (VIM).
Calibration is a process that is used to define metrological properties of a measuring system or measuring instrument. Firstly, the relationships between quantitative variables are established under defined conditions with a measurement uncertainty established via the reference standard.
Secondly, rules are defined according to which the measurement results are obtained from the displayed values.
A written document in paper or electronic form containing the results of a calibration.
Factor used to expand the confidence interval in order to ensure a normal distribution of the measured values. A coverage factor of
= 2 should generally be applied to calibration certificates. The value depends on the effective degrees of freedom of the measurement uncertainty calculation.
D E F
Deutsche Akkreditierungsstelle GmbH
This is the national accreditation body of Germany (German Accreditation Body, DAkkS). It acts in accordance with Regulation (EU) 765/2008 and the German Accreditation Body Act (Akkreditierungsstellengesetz, AkkStelleG) in the public interest as the sole service provider for accreditation in Germany.
Degree of freedom, effective
The degree of freedom is calculated using the Welch-Satterthwaite equation. The coverage factor k is determined from the number of degrees of freedom.
Deutscher Kalibrierdienst (German Calibration Service)
Technical committee of calibration laboratories under the patronage of Physikalisch-Technische Bundesanstalt,
. The accreditation tasks in the field of metrology were transferred to
at the start of 2010.
European co-operation for Accreditation
European association of national accreditation authorities.
An estimated value is the value of a measurand obtained via measurement with a real measuring instrument (subject to a measurement uncertainty due to losses, environmental influences, temperature etc.).
G H I
Guide to the Expression of Uncertainty in Measurement
full name of the document JCGM 100.
see JCGM 100
In the case of AC current, this is used to describe the RMS value (or effective value) of the current.
Peak value of the measurand 'current'
An important measurand particularly for impulse currents and AC current.
International Accreditation Forum
International association for the conformity of accreditation bodies; its task is to prepare the
Mutual Recognition Arrangement (MRA).
International Laboratory Accreditation Cooperation
International association of accreditation bodies for laboratories and inspection agencies
Mutual Recognition Arrangement
International mutual recognition arrangement between MRA signatories.
General requirements for the competence of testing and calibration laboratories
Actually valid issue from 2005. General requirements for the competence of testing and calibration laboratories
J K L
Joint Committee for Guides in Metrology
A metrological organisation located within BIPM and responsible for publication of metrological documents, for example JCGM 100 and JCGM 200.
Guide to the Expression of Uncertainty in Measurement
Fundamental document on the calculation of measurement uncertainty.
JCGM 100 S1
Guide to the Expression of Uncertainty in Measurement, Supplement 1
Supplement to the JCGM 100 document. The document provides practical examples that show measurement uncertainty is calculated during a measurement.
International Vocabulary of Metrology
The International Vocabulary of Metrology defines all of the technical terms used in metrology. The glossary is regularly updated and published. It is available in English and French and can either be downloaded as a PDF file or accessed in its online version via the website of the JCGM committee.
See 'coverage factor
M N O
The measurement uncertainty (sometimes incorrectly referred to as the measuring error) of a measurement is an indicator of inadequacies in a measurement process. It expresses the extent to which a measured value differs from the
The combined measurement uncertainty multiplied by the coverage factor
The measurement uncertainty is calculated from individual measurement uncertainty contributions, which are combined using the error propagation law.
Measurement uncertainty contribution
The magnitude of a measurand, measurement process, measurement condition etc. that contributes to the measurement uncertainty. The combined measurement uncertainty is calculated by adding the measurement uncertainty contributions in accordance with the error propagation law.
Office of weights and measures
Official authority that performs official verification, which is a sovereign task of the state.
Test to determine whether or not the measurement uncertainty of a measuring system is within the prescribed limits. Official verification is performed by Physikalisch-Technische Bundesanstalt, ( PTB), national offices of weights and measures or by state-certified examining bodies. Not to be confused with calibration.
P Q R S
The active power component of AC power is the real part of the complex apparent power S. This component of electric power describes the energy consumption and expresses itself in the form of mechanical work, heat or similar.
A performance check is a form of control measurement, It is a simplified calibration that is used to verify the metrological properties of a measuring system or measuring instrument. These control measurements are referred to as a
performance check in the relevant standards
The reactive power of AC power is the imaginary part of the complex apparent power
and describes the energy required to generate an electric or magnetic field in an object (in a capacitor, motor etc.).
Physical embodiment of a physical measurand with a defined magnitude and measurement uncertainty, which acts as a reference.
- Apparent power
The apparent power of AC power is a quantity that is obtained by multiplying the AC current
that flows through an an object with the voltage drop
across the object. The apparent power is not the same as the consumption of the object. Apparent power is made up of effective power
and reactive power
T U V
The process of 'tracing back' is the performance of a comparison measurement between the object under calibration and the international reference standard. The comparison can be performed in two ways:
- directly, by performing a comparison measurement against the international reference standard; or
- indirectly via a transfer standard that has already been traced back . The transfer standard can, itself, be traced back directly or indirectly. The key factor in the process of tracing back is establishing an uninterrupted chain of traced-back comparison measurements between the object under calibration and the international reference standard.
The physically correct value of a measurand that is measured in an ideal case.
In the case of AC voltages, this describes the RMS (effective) value.
Peak value of the measurand 'voltage'
This is an important measurand, particularly for impulse voltages and AC voltages. The designations
m are also used.
International Vocabulary of Metrology see JCGM 200.
W X Y Z
Statistical equation for calculating the effective degrees of freedom of a measurement uncertainty calculation. The result of the equation enables the choice of the coverage factor
. With the aid of the coverage factor it is possible to calculate the expanded measurement uncertainty from the combined measurement uncertainty.
Circuit for implementation of a comparison measurement on high-voltage systems
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