National Measurement Standards

Electrical quantities

The metrology laboratory provides calibration of measuring equipment for electric quantities, is engaged in the preparation of measurement and calibration procedures and concerned with the development in the given field.

Apart from calibrations according to the established calibration procedures, the laboratory develops new and improved procedures to ensure calibration of new and more and more precise measuring instruments. Furthermore, it participates in international projects, mainly to get familiar with the most recent discoveries in the metrology field and to apply this new knowledge in the laboratory.

On the basis of internal and international research projects, the laboratory has developed quite a few measurement procedures and some of its own measuring equipment that is comparable to the best measuring equipment in the world. The laboratory has developed its own coaxial alternating current shunts enabling extremely precise measurement of alternating-direct current difference, as well as the measurement of alternating current by means of the voltage drop in a shunt, which is a novelty in the filed of alternating current measurement. The newly developed measurement method has simplified the calibration of alternating current in practically entire measurement equipment available on the market. The method has been presented also in the recognized magazine IEEE.

The laboratory has also designed voltage range resistors that are not available on the market. In combination with thermal converters these voltage range resistors enable precision measurement of alternating-direct voltage difference and alternating voltage.





One of the important areas of development is the development of our own algorithms for measurement of individual electric quantities. Among them, the numerical algorithm for the determination of the amplitude, frequency and phase of a sample signal bears the most importance. Despite its simplicity, it allows small errors, due to which it is comparable, if not even better, to more complex algorithms currently in use for this purpose.





In addition to the already mentioned projects, there are also internal projects for the development of new measuring equipment and measurement procedures to meet the needs of the Slovene economy. The established methods are further developed and upgraded to improve measurement uncertainty. Apart from that, there are always new needs for the development of methods for quantities not yet covered by the accreditation.

The result of continuous development and ever new calibration needs is one of the broadest accreditation schemes in the field of electric quantities covering the following quantities:

  • direct and alternating current,
  • direct and alternating voltage,
  • alternating – direct voltage and current difference,
  • direct and alternating power,
  • resistance,
  • impedance (capacitance, inductance, AC resistance),
  • optical fibres,
  • acoustics,
  • high-frequency area:
    • RF power,
    • RF impedance and RF attenuation,
    • signal analyses,
    • oscilloscopes,
    • spectrum analyzers,
    • distortion, modulations,

The traceability of individual quantities is ensured by the calibration of national measurement standards in foreign national laboratories (NMIs). The calibration procedures have been developed in such a way that a minimum number of reference measurement standards is sent to foreign NMIs to ensure traceability, while all work measurement standards and other measuring instruments are calibrated in our laboratory according to our own procedures. In this way we make best use of our own knowledge, reduce the costs of calibrations abroad, and shorten the absence of key measuring equipment from the laboratory.

To get the confirmation of our own methods, the laboratory also participates in international interlaboratory comparisons.