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Successful comparison measurements between DAkkS-accredited laboratories for accelerometer calibration and the PTB


A series of comparison measurements between the DAkkS-accredited calibration laboratories for the unit of acceleration and the PTB confirms the high quality level of the German traceability system in this field. The excellent results have been published internationally.

In the period from October 2010 to August 2011 a series of comparison measurements was performed between the accredited laboratories [1] of the working group “Acceleration” of the German Calibration Service (DKD) based on the currently applicable ISO standards [2] and [3] as well as the national Guideline DKD-DAkkS-R 3-1 [4]. The excellent results were published in [5].

Nine accredited as well as one non-accredited laboratories participated in the series. The role of the pilot-laboratory, responsible for the organisation and the monitoring of the stability of the artifacts, was taken over by the company SPEKTRA  Schwingungstechnik und Akustik GmbH Dresden (DKD-K-27801). This laboratory, besides PTB, provides the lowest measurement uncertainties in the group and is the only accredited laboratory applying primary calibration.

Task of the comparison was the measurement of the complex coefficient of sensitivity of three accelerometers covering the frequency range from 0.2 Hz to 10 kHz, as well as the determination of the complex transfer function of signal conditioners for charge with three different input charges and for IEPE with and without coupled power supply in the frequency range from 0.2 Hz to 50 kHz.

Traceability oft he results according to ISO 16063-11was realized by the inclusion of PTB’s laboratory for “acceleration” as reference laboratory. Analysis and assessment of the measurement results was also part of the PTB involvement. By means of the En criterion the consistency of the individual results for magnitude and phase was checked.

The series of comparisons had a star-like topology starting with a primary calibration of sensors and conditioners at the PTB, after the last participant’s measurement the final calibration was performed at PTB, too.

The monitoring measurements of all artifacts by the pilot laboratory in the time slots in between consecutive participants (10 measurements in 11 months) showed an excellent stability of the devices.

For the assessment of the individual results of each participant the so called En value was calculated taking into account the measurement uncertainty of both the participant and the PTB. This was done for the magnitude and phase of the measured complex response. For both quantities the En value should be less than 1.0, to confirm that the participant meets its accredited measurement uncertainties. Figures 1 and 2 show an overview of the results.

Fig. 1: Statistics for the measurement of the magnitude

Fig. 2: Statistics for the measurement of the phase

In summary the comparison measurements reflect the high quality level of the German accredited laboratories for acceleration and related signal conditioners. No deviations from the accredited services were observed within the comparison results. Beyond that the measurements pointed out some areas of upcoming challenges. This concerns the phase calibration of charge amplifiers under difficult conditions and the calibration of IEPE conditioners while the power supply current is on. These will be topics of future collaborative work in the DKD working group acceleration.


[1] ISO/IEC 17025:2005 General requirements for the competence of testing and calibration laboratories

[2] ISO 16063-1:2003 Methods for the calibration of vibration and shock transducer –Part 21: Vibration calibration by comparison to a reference transducer

[3] ISO 16063-1:1999 Methods for the calibration of vibration and shock transducer – Part 11: Primary vibration calibration by laser interferometry

[4] Richtlinie DAkks (DKD)-R 3-1 Kalibrierung von Beschleunigungsmessgeräten nach dem Vergleichsverfahren (in German)

[5] Th. Bruns, Ph. Begoff, M. Mende: Realization and results of a DKD interlaboratory comparison regarding the measurend acceleration; XX IMEKO, September 9-14, 2012, Busan, Republic of Korea

Contact person:

Thomas Bruns, Dept 1.7, WG 1.71, e-mail: thomas.bruns@ptb.de