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Direct Current Measuring Techniques

Working Group 2.11


The Working Group 2.11 is responsible for the maintenance and dissemination of the electric units for resistance, voltage and current.

For the unit of current the scale is build-up from 1 fA to 100 A. This is realized by classical methods (voltage ramp and capacitor, voltage and resistance, and current comparators).

The dissemination of the unit of electric voltage ranging from 1 V to 10 V is carried out by direct comparison to a standard measuring device based on the Josephson effect.

For the unit of resistance the scale is build-up from 100 μΩ to 1 GΩ. In the range of 1 Ω to 10 MΩ resistance ratios can be realized with a cryogenic current comparator.

Another area is the calibration of the electrical conductivity of metals. The conductivity is determined using a direct current method.


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Maintenance of the unit resistance

Research is taking place to develop new types of standard resistors. Standard resistors are to be characterized such that environmental conditions have the least possible influence and their aging behavior is predictable.


Extension of the measuring range for the electrical conductivity

Currently, work is underway to extend the measurement range to lower conductivities (< 0.5 MS/m), to characterize semiconductor materials.

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The working group performs calibrations of standards for accredited laboratories, industry, other national metrology institutes and for research. The dissemination of the resistance scale ranging from 100 μΩ to 1 GΩ is done by calibrating standard resistors. The dissemination of the unit of electrical voltage at the values 1 V, 1,018 V and 10 V is performed by calibration of electronic voltage standards. Voltage sources and meters can be calibrated in the range from 1 µV to 1000 V. Calibrations of current sources and meters are possible in the range of 1 fA to 100 A.

The voltage and resistance values are based on the internationally defined constants KJ (Josephson constant) and RK (von Klitzing constant).

Calibrations in the conductivity of metals are possible in the range from 0.5 MS/m to 65 MS/m.

Assessment of calibration laboratories for electrical quantities on behalf of the German Accreditation Body
Calibration laboratories are assessed on behalf of the German Accreditation Body (DAkkS).

The working group provides expert advice in the field of DC metrology.

Measurement capabilities
Link to the calibration and measurement capabilities (available in German only)

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The working group presently does not offer any further information.

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