Many medical measuring devices (MMD), such as those used in clinical diagnostics, use optical absorbance as the measurand. Optical absorbance in MMDs is usually measured in microvolumes, according to pharmaceutical quality standards; some instruments should also be calibrated for absorbance at required specific wavelengths due to their construction. Optical absorbance liquid filters (OALF) are used to calibrate optical absorbance measurement equipment, but there is currently a capability gap across NMIs in the characterization and use of such filters, which leads to a lack of traceability. Currently, precise calibration methods of MMDs for absorbance at required specific wavelengths are not possible using commercially available liquid traceable standards and the calibrations are performed at approximate wavelengths and absorbance levels. This paper describes the take up of traceable measurement capability of absorbance of liquid filters, the assessment of INRiM facility and the progress in the development of new OALF.

Measurements of electromagnetic fields in the vicinity of overhead power lines are carried out in order to assess the exposure of the general public to these fields and to check whether the field levels are within the prescribed limits. Since the measurement results are compared with the prescribed reference levels, the measurement uncertainty should be evaluated and taken into account in the conformity assessment. The paper analyzes the most relevant uncertainty components related to measurements of electric and magnetic fields near overhead power lines. The uncertainty components related to the calibration of the measuring system, proximity of the operator and positioning of the measuring probe are analyzed and evaluated for the real example of measurements near an overhead power line. In order to provide the validity of the measurement results the measurements are carried out with two measuring systems and they are also compared with the calculation results.

The calibration of high frequency instruments, like oscilloscopes or frequency counters, is a metrologically very intensive task, due to: complex measurement procedures, unattested SI measurement traceability chain for high frequencies signals, and numerous uncertainty contributions. These calibrations are to some extent prescribed in the Euramet cg-7 Guideline. The uncertainty models for calibration of oscilloscopes, introduced by the Laboratory for Electrical Measurements at the Ss. Cyril and Methodius University in Skopje are presented. An original software developed in LabVIEWTM, MonteCalc Uncertainty Toolkit, based on both methods, the GUM and the stochastic Monte Carlo approach for uncertainty evaluation is applied on experimental data from laboratory calibration of a high frequency oscilloscope with over 500 MHz range. The results from the two methods are compared and discussed. Based on the uncertainty propagation distribution gained, conformity assessment of the artefact of calibration in particular measurement points, is made against prescribed decision making rules embedded in the MonteCalc Uncertainty Toolkit.

The application of analytical methods in power transformer (PT) condition assessment enables the separation, identification and quantification of degradation products or contaminants, which are present in mineral transformer oils in low concentrations (mg/kg, μg/kg). This paper presents a review of the key instrumental methods applied in the laboratory of the Nikola Tesla Institute (NTI) and emphasizes the importance of their application during transformers life cycle. Gas chromatography (GC) is applied for assessment of PT operating condition and fault detection, cellulose degradation and for quantification of contaminants (PCB) and corrosive sulphur compounds (DBDS, S8) in insulating liquids. Liquid chromatography (LC) is applied for testing the presence of specific additives, such as metal passivators and degradation products such as furanic compound in oils. The importance of applying infrared spectrophotometry (IR) is reflected in the analysis of the chemical composition and antioxidant content (DBPC) in the oils. The results of Round Robin Tests (RRT) are also presented in this paper.

Adherence to ISO/IEC 17025:2017 requires inter-laboratory comparisons and proficiency testing, alongside other measures, for ensuring test and calibration data validity. This study explores intra-laboratory comparison, as an additional quality assurance method. The presented procedure is conducted in an accredited calibration laboratory, by comparing results sourced/measured with multiple reference standards, including a high-voltage decade resistor, 8 ½ and 6 ½ digit multimeters, and a multifunction calibrator with a high-resistance measurement adapter, all of them covering the range of high resistance, above 100 MΩ. By applying the ISO/IEC 17043:2023 statistical methods and En criteria, the quantitative assessment of the measurement consistency is achieved, thus enhancing the confidence in the laboratory’s standards.