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1. Direct Current and Low Frequency

Karl-Peter Lallmann

DKD's Technical Committee Direct Current and Low Frequency deals with the calibration of electrical measurands in the frequency range from 0 Hz to 1 MHz. At present, the Technical Committee has 108 members. The Committee comprises accredited calibration laboratories as well as interested persons and representatives from PTB. Given its large number of members, work on technical issues is rather difficult to manage. For this reason, some of the members have formed small groups where they deal with the preparation of calibration guidelines – especially with the support of VDI, the Association of German Engineers (VDI/VDE-GMA Technical committee 3.12). Over the last 25 years, for example, this cooperation has resulted in the calibration guideline series VDI/VDE/DGQ/DKD Part 2622 ff. By translating this series of calibration guidelines into English, it is intended to achieve greater acceptance outside the German-speaking countries as well.

The Technical Committee meets once a year to exchange information. During these meetings, reports from the DKD Board, the corresponding Sector Committee of the German Accreditation Body (DAkkS), and the Technical Advisory Board 5 of the Accreditation Advisory Board of the Federal Government are presented. Moreover, the agenda covers

·      the current status of the VDI/VDE/DGQ/DKD guidelines and discussion

·      information provided by / or presented to DKD's Technical Committee on Measurement Uncertainty

·      comments / recommendations regarding calibration techniques

·      comments / recommendations for the evaluation of measurement results

For example, current topics are the Digital Calibration Certificate (DCC) and the organisation and realisation of interlaboratory comparisons. Here, we strongly rely on the support of PTB. These as well as other topics are addressed in close cooperation with PTB, representatives of DAkkS and members of other Technical Committees.
Apart from the respective VDI/VDE/DGQ/DKD guidelines, the Technical Committee has published the following calibration guideline:

·      DKD-R 1-1: Measurement and generation of small AC voltages with inductive voltage dividers