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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 ratio and the electric units for capacitance, inductance and ac resistance. The dissemination of ac voltage ratio and the unit of ac resistance is carried out with measuring systems based on inductive voltage dividers and sampling techniques.

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The research and development activities of the working group comprise the development of digital and digitally assisted impedance bridges for the calibration of capacitance standards, AC resistors, phase meters and phase standards.

These activities are based on the development of inductive voltage dividers and traceable sampling systems 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.

This includes:

  • 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)
  • Capacitance standards
(1 pF to 10 mF, 50 Hz to 1 MHz)
  • Inductance standards
(1 pF to 10 mF, 50 Hz to 1 MHz)
  • AC resistors
    (resistance and time constant)

(1 µH to 100 H, 50 Hz to 1 MHz)
( 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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