Training on measurements to determine the characteristics of three-phase electrical systems is very useful for a deep knowledge of the theoretical aspects, particularly for electrical engineering undergraduates. The technological development requires the realization of tools which gradually familiarize the students with advanced technologies for measurement during the training activity. Three different tools have been implemented during the last three years in order to improve on purpose the didactic value of the laboratory sessions. In the first tool a complex hardware and software system is implemented: the system includes electromechanical instruments for a better understanding of the three-phase system operation and can be used in distance learning sessions, on account of the realized virtual instrument. The second tool provides different features from the previous one: indeed, it is based on advanced technologies and has been redesigned in order to realize an electronic power meter, active and reactive, in a wide range of current values. The last tool is a didactically valuable three-phase energy meter, an industrial technical instrument, ready to be characterized in the next future.

ADC testing frequently confronts the problem of spectral purity of harmonic test signal. The majority of dynamic ADC test methods require test signal distortion at least 10 dB less than that of the tested ADC – the condition that cannot be practically fulfilled for testing up-to-date ADCs. More sophisticated approach to ADC testing applies the correction for test signal imperfections. In both cases test signal distortion has to be known – roughly in the first case and quite accurately in the second case. In this paper an easy method for the testing of signal spectral purity is proposed. Test signal passed by one of two simple analog filters is measured by a common ADC, whose nonlinearity is mathematically post-corrected. The results are compared with common approach applying notch filter and uncertainty analysis is performed.

The paper describes the design phase of a portable gonio-reflectometer for the measurements of the reflection properties of road paving directly on site. The importance of these measurements is highlighted, then the measuring procedure is briefly described together a presentation of the organization of the instruments itself and the design criteria. Attention is focused on the positioning of the light sources exciting the surface under analysis and on the errors which can appear in the evaluation of the performance of a road lighting plant designed on the measurements realized by the portable gonio-reflectometer, in particular.

In this paper we illustrate that magnetic hysteresis affects the uncertainty of sensors based on magnetic phenomena and materials. Testing various magnetic techniques, we conclude that sensor uncertainty can be optimized by both, the optimization of magnetic hysteresis and the operation in the magnetically reversible area of the material. Preliminary modelling results are in agreement with our experimental findings.

The paper presents a new approach to processing of the cumulative code histograms obtained at ADC histogram testing by exponential stimulus signal. The analytical base model requires calculation of logarithms that may not be convenient for implementation in some applications. The authors proposed two new approximation models of cumulative and code histograms derived from the analytical base model: recurrent model with rectangular rule and asymptotic model with the goal to simplify approximation process. The recurrent model is convenient for the implementation especially in digital signal processor because it uses only basic arithmetic operations. Estimation process using this model is also faster than using base one. The asymptotic model enables the fastest approximation of required parameters. The models were experimentally compared by simulation using Levenberg–Marquardt and Newton iteration algorithms.