Giovanni Betta, Domenico Capriglione, Claudio De Capua, Carmine Landi
A COMPARATIVE ANALYSIS IN TERMS OF CONDUCTED SUSCEPTIBILITY OF PC-BASED DATA ACQUISITION SYSTEMS

In this paper, a performance comparison between PC-based data acquisition systems is carried out with reference to their immunity to electromagnetic conducted disturbances. The aim is to identify suitable measurement procedures at present not available both in the literature and in EMC standards. The data acquisition system (personal computer and data acquisition board) is approached as a whole system and subjected to the more relevant conducted interference considered by EN standards, electrical fast transient and noise by conducted radio frequency field. Experimental tests, carried out in a shielded environment, highlight the relevance of a specific EMI characterisation of this apparatus.

L. Asnin, V. Backmutsky, M. Sedlachek
USING DSP METHODS FOR ACCURATE DYNAMIC MEASUREMENTS IN POWER SYSTEMS

This paper presents the results of comparison of a new method of magnitude spectrum estimation of periodical signals in Power Systems, which uses Discrete Fourier Transform (DFT) and special FIR filters, with other methods of spectrum analysis, based on a preliminary estimation of the dynamically changed signal frequency. The main purpose of the suggested method is to reduce the leakage errors under conditions of desynchronization between the signal and the sample frequencies. Digital modeling of this method shows that accuracy of the estimation of magnitudes of the signal harmonics increases essentially by reference to other methods based on the interpolation of samples. This method can be used especially in Power System dynamics investigation (relay protection, UPS tuning, etc).

Cipriano Bartoletti
MODELLING AND MEASUREMENTS ON A DEVICE FOR CURRENT FOCUSING IN AN ELECTROLYTIC PROCESS

An electrical model of ionic current distribution in electrolytic solutions, in asymmetrical geometry of electrodes, is proposed. The results are compared with the known ones carried out by a software specialised in symmetrical current flow computing. By means a systematic campaign of computing, the electrical and geometrical parameters of a ionic current focusing device are found. A computer controlled experimental apparatus, based on such parameters, is also presented. Early measurements on this device seem to confirm the model validity.

J.C. Villarroel Poblete
FORCE TRANSDUCER CALIBRATION COMPARISON BETWEEN PTB (GERMANY), CEM (SPAIN) AND LABORATORIO CUSTODIO DE PATRONES NACIONALES DE FUERZA (CHILE)

A force transducer calibration comparison was carried out between Laboratorio Custodio de Patrones Nacionales de Fuerza (in Chile), Centro Español de Metrología (in Spain) and Physikalisch-Technische Bundesanstalt (in Germany), in order to compare and to evaluate the results of the calibrations of force transducers. The calibration comparison was carried out for the range of 100 kN.
The calibrations was made in conformity with the standard ISO 376:99. The results obtained, the deviation graphs that include the uncertainty for each laboratory are presented in this document.

Boris Katz, Liron Anavy, Itamar Nehary
CALIBRATION OF CONCRETE COMPRESSION TESTING MACHINES PRODUCTS

A wide spectrum of compression testing machines is used for strength testing of concrete pipes. The main specialty of the testing machine is the length (2-2.5 meters) of the tested product (pipes), which requires a loading beam with corresponding length. Non-parallelism of supporting and loading elements, unequal distribution of loads, a big parasite torque effort because of the loading elements’ large size leads to another measurement errors and to increased uncertainties in calibration process according to ISO 7500-1:1999. For making the right choice in using and setting measuring elements (load cells) and accessories, one must take into account the structure and technological specialties of the testing machines: how many pistons are in it, the method of pressure measurement, the arrangement of measuring and supporting elements in the machines. In this paper we analyze in detail the different measuring methods and recommend choosing the best method of calibration, which most diminishes the uncertainty.