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Po Gyu Park, V. Ya. Shifrin, V. N. Khorev, Y. G. Kim
A MEASUREMENT SYSTEM FOR PROTON GYROMAGNETIC RATIO DETERMINATION AS A BASIS FOR A MAGNETIC FLUX DENSITY STANDARD

The proton gyromagnetic ratio (γ'P) plays a fundamental role in achieving highly accurate magneticfield measurements. At the KRISS complex for the determination of the proton gyromagnetic ratio, we have improved a magnetic-field standard based on the value of γ'P and related techniques. The standard for measuring DC magnetic flux density is intended to cover the range from 20 µT to 2.5 T, with an uncertainty ranging from 4·10-6 to 6·10-5 T.

Mladen Boršic, Damir Ilic, Nadža Milanovic, Luka Ferkovic, Pasquale Daponte, Aniello Cimitile, Sergio Rapuano, Mihail Marinov, Andrea Aiello, Gianpaolo Mercurio, Gioachino Truglia, Višnja Gašljevic, Roman Vulpe
ESTIMATION OF THE UNCERTAINTY IN MEASUREMENT OF THE ELECTRIC ENERGY - ITALIAN-CROATIAN PROJECT

The Faculty of Electrical Engineering and Computing Science, University of Zagreb and the Faculty of Engineering University of Sannio signed, in the year 2001, the Agreement of Cooperation International Co-operation for the Research Doctorate in Information Technology with the aim at collaborating for the activation and the development of joint doctoral degree courses.
The President of the Province of Benevento and the President of the City Assembly of Zagreb signed, the same year, the Letter of intent for cooperation. As the first step in this cooperation will be the realisation of the Italo-Croate project Estimation of the Uncertainty in Measurement of the Electric Energy funded by the Italian Ministry of Education, University and Research (Ministero dell'Istruzione, dell'Universita e della Ricerca) and Croatian Ministry of Science and Technology (Ministarstvo znanosti i tehnologije).
The eolic electric energy, as a pure energy, becomes increasingly important in Italy. The high voltage to medium voltage transformer sub-stations in Montefalcone, having installed energy of about 180 MVA, will be the test stations to evaluate the uncertainty in measurement of electric energy generated by eolic generators. The result should be the fair and transparent energy rating.
The group of researchers from Faculty of Electrical Engineering and Computing, University of Zagreb, Croatian Metrology Society, Zagreb, and Universita degli Studi del Sannio, Benevento will try to find all the sources of possible errors in measurements. At the end, two or three researchers will carry out internationally recognised doctorate dissertations.

Ivan Lenicek, Roman Malaric, Alan Šala
AN ACCURATE COMPARISON OF HIGH-OHM RESISTANCES USING IMPROVED DVM-BASED SYSTEM

For purpose of accurate resistance standards comparison a digital voltmeter (DVM) based method has been designed and realized. When measuring resistance standards greater than 100 MΩ capabilities of the method are restricted due to influence of DVM's input parameters: input resistance, input offset current and input capacitance. The measurement system for resistance comparison based on two DVMs has been improved using simple electrometer transconductance amplifier that interfaces digital voltmeter with the measuring circuit. Analysis of influence of electrometer's parameters, realization of the electrometer device and calibration of the system has been presented in this paper. Described measurement system has been merged in resistance traceability chain of Primary Electromagnetic Laboratory (PEL) within the Faculty of Electrical Engineering and Computing of the University of Zagreb, thus participating in building of high-ohm resistance standard base up to 1 TΩ.

Jerzy Nabielec, Barbara Bisztyga
DYNAMIC ERROR CORRECTION FOR MEASUREMENT SYSTEM WITH DIFFERENTIATING SENSORS

The dynamic measurement is considered. The measurement system with differentiating sensor is taken into account. The 'blind' method has been applied to solve the dynamic error correction. Discrete time corrector has been adapted. Simulation technique has been used to verify the usefulness of the correction.

Peter Kral, Harald Hackl
DETERMINATION OF SOUND CAUSED BY COMPRESSOR VALVES USING TIME SIGNAL ANALYSIS

The measurement of sound levels of noise sources located very closely together – for example the inlet and outlet valve of a piston compressor – is a difficult task. This paper describes a method to evaluate the emitted noise levels of each valve. To achieve precise results, an analysis of the sound pressure level depending on time (time-signal) was done. Signal processing and computations of the measurement results lead to clearer separation of the sound emitted by each sound source (valve).

R. Micheletti, R. Pieri
WALSH DIGITAL FILTERING ALGORITHM FOR HIGH SPEED DISTANCE PROTECTION WITH IMPROVED BEHAVIOR

Distance relays must estimate accurately and quickly the distance to the fault even in presence of highly distorted input signals. Several digital filtering algorithms for distance relays have been proposed and some of them are used in practical applications. However nonlinear loads are becoming more and more common in electric power systems and that increases the corruption level of signals. For this reason, the study of digital filtering techniques for the extraction of fundamental components from highly corrupt voltage and current waveforms is of vital importance for the development of algorithms applied to the digital protection of transmission lines. The studied technique proposed in this paper is based on Walsh functions.

Jerzy Nabielec, Jacek Nalepa
THE 'BLIND' METHOD OF DYNAMIC ERROR CORRECTION FOR THE SECOND ORDER SYSTEM

The paper presents results of simulation investigations of the measuring system, which enables measuring, with very small dynamic error, of rapidly changing signals using inexpensive transducers of not particularly good dynamic performance. Two methods for self-identification of the system sensor parameters are presented. The self-identification is performed using solely the measured signal at the system operating site. The system itself performs the correction of dynamic errors. Therefore the system shows small sensitivity to adverse influence of the operating conditions on the transducers dynamic properties. The investigations have been carried out for the second order, oscillatory and inertial transducers. The presented methods of correction can be applied to measuring of both: periodic and non-periodic signals. The simulation results, presented in a graphical form, illustrate the dependence of the correction effectiveness on the system selected parameters. Created programming tools make possible for testing the system in the neighbourhood of the selected operating point.

Michal Lisowski, Ryszard Kacprzyk, Edmund Motyl, Pawel Galezki
SPACE CHARGE INFLUENCE ON THE RESUTS OF VOLUME RESISTIVITY MEASUREMENTS IN SOLID DIELECTRICS

The problems associated with measurements and determination of volume resistivity were presented in the paper. Special attention was paid to the measurements carried out on extremely high resistivity materials. Space charge influence was discussed as the most important factor affecting the uncertainty of results of the resistivity measurements.

Vaclav Papez, Stanislava Papezova
MEASURING OF NON-LINEARITY OF NOMINALLY LINEAR ELECTRONIC COMPONENTS AND NETWORKS

Traditional methods and new method for the small non-linearity measuring of electronic components and circuits are described in this paper. There are presented examples of measured intermodulation product levels on passive components.

Ivan Krejcí, Jana Parílková
INSTRUMENTATION USED FOR DIKES MONITORING

Instrumentation technique and processing of analog and digital signals in specially designed equipments are described. Parameters of instruments that have been built for purposes of the thermal scalar field monitoring and for electrical impedance spectroscopy are discussed.

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