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Ratio Measurements and Impedance

Working Group 2.12


Working Group 2.12 is responsible for the maintenance and dissemination of ac voltage ratios and the electric units for ac resistance.

The dissemination of ac voltage ratios and the unit of ac resistance is carried out with measuring systems based on inductive voltage dividers and sampling techniques. Typical measurement voltages up to 10 V at frequencies up to 5 kHz are used.

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Extending the frequency range of the measurement capabilities

Due to the increasing requirement for industrial applications we are extending the measurement frequency range up to 100 kHz.

The developments include new inductive components and traceable sampling systems for frequencies up to 100 kHz.


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The Working Group performs calibrations of standards for accredited laboratories, industry, other national metrology institutes, and for research.

Based on the ac voltage ratio and ac resistance measurement capabilities several standard are calibrated which include:


  • Inductive voltage dividers
(1 V bis 100 V, 25 Hz bis 5 kHz)
  • Bridge standards for use in
    strain gauge measurements
(1 V bis 10 V, 225 Hz bis 5 kHz)
  • AC temperature bridges
(1 V, 25 Hz und 75 Hz )
  • Attenuator boxes
(10 V, 400 Hz und 1 kHz)
  • Synchro/Resolver bridges
(10 V, 400 Hz)
  • Phase angle meters
(0,1 V bis 7 V, 10 Hz bis 1 kHz)
  • Two-channel measuring amplifier
    (amplitude and phase, complex AC voltage ratio)
(2 mV bis 5 V, 0,3 Hz bis 5 kHz)
  • AC resistors
    (resistance and time constant)
( 0,1 Ω bis 100 kΩ, 400 Hz)


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 above mentioned metrology of ac voltage ratios.


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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