Jan Tomlain, Radek Sedlacek, Josef Vedral
PARTIAL DISCHARGE DIAGNOSTIC SYSTEM FOR NON-DESTRUCTIVE TESTING OF HIGH-VOLTAGE MACHINES

This paper deals with the complex design of the partial discharge system for high-voltage machines diagnostics. The result of the work is complete measurement system, which fulfils specified functionality. Implementation relies on the FPGA with the advantage of system-on-the-chip technology. This solution enables flexible and powerful signal processing. Measurement principles and methods together with the test results are also mentioned.

Tomasz Tarasiuk, Andrzej Pilat
A SHORT DISCUSSION ABOUT IMPACT OF TIME WINDOW SYNCHRONIZATION ERROR ON ACCURACY OF HARMONIC SUBGROUPS MEASUREMENT – EXPERIMENTAL RESEARCH

The paper is focused on the problem of insufficient synchronization of measurement time window with actual duration of integer number of cycles of input signal and its impact on accuracy of harmonic subgroups measurement. It is analyzed in the wake of chief provisions of IEC Standard 61000-4-7. Particularly, the harmonics order, their phases and the synchronization accuracy have been considered. Numerous simulations has been carried out and their results are graphically presented. The results have been confirmed by experimental research of chosen testing signals, generated by arbitrary waveform generator.

F. Attivissimo, G. Cavone, A. Di Nisio, M. Savino, M. Spadavecchia
DESIGN OF A VIRTUAL INSTRUMENT FOR ELECTRICAL POWER SYSTEMS WITH GENERATION OF DISTURBANCES

In this work, a Three-Phase Virtual Dummy Load able to generate six arbitrary distorted waveforms is described. The proposed system, is able to emulate a mono or three-phase system of symmetrical/asymmetrical voltages and a lot of different loads balanced or unbalanced and three types of disturbances. The proposed system is the testbed for a PQ energy meter prototype and is also useful to validate new algorithms for PQ events identification implementable in embedded systems.

M. D’Apuzzo, D. Grillo, R. Schiano Lo Moriello
MEASURING FREQUENCY OF NOISY SIGNALS THROUGH A STOCHASTIC RESONANCE APPROACH

The paper deals with the problem of measuring the frequency of sinusoidal signals hardly buried in noise. Stemming from their past experience on the topic, the authors suggest a new method based on the stochastic resonance capable of outperforming their previous proposal when acquired signals characterized by very low signal-to-noise-ratio (even lower than zero). In particular, the method exploits the peculiar resonance condition that double threshold system exhibits in the presence of an optimal noise level superimposed to the useful signal.
Preliminary tests carried out on numerical signals confirm the promising performance of the method and its possible implementation on cost-effective platform, thanks to its reduced computational burden.

Alexandru Salceanu, Fanel Iacobescu, Marius Valerian Paulet, Mirela-Adelaida Anghel
APPROACH ON MEASURING THE SURFACE RESISTIVITY OF ESD FABRICS

The paper mainly deals with the influence of the applied measuring voltage on the surface resistance/resistivity of 19 fabric samples, being representative for the various technical solutions of obtaining static dissipative textiles. There were chosen for exemplification six samples with various behaviors regarding the relationship between the increasing excitation DC voltage and the measured results. Based on the Keithley’s hard and soft infrastructure, it was developed the Alternating Polarity method, with a sweep of voltage, nine equal steps from 90V to 990V. There were plotted graphs presenting the different trends of the material response at various excitation voltages. The significant number of performed measurements allowed us to pick up and test possible explanations or just hypothesis for different and sometime unexpected performances of the conductive insertion technologies, aiming to transform the fabrics from very good insulators into static dissipative materials.