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Page 935 of 955 Results 9341 - 9350 of 9546

Ivan Gašparac, Zlatko Maljkovic, Mario Vražic
VIBRATIONS MEASUREMENT DURING HYDROGENERATOR TESTING

This paper presents the results of vibration measurement during several specific tests of 35 MVA hydro-generator.

Jiri Brossmann, Jaroslav Roztocil, Vojtech Ruml, Dusan Varga
SOFTWARE DEVELOPMENT FOR ADC TESTS

Object based universal software system for ADC testing which enables an easy programmer’s access and expansion (update) is introduced in this paper. The basic idea of the object oriented design and some aspects of the software solution of the ADC testing are described.

Josep M. Torrents, Ramon Pallàs-Areny
SENSING OIL CONDITION THROUGH TEMPERATURE COEFFICIENT OF DIELECTRIC CONSTANT

Time-scheduled oil changes in internalcombustion engines are often performed well before the oil starts to significantly lose its lubricating properties. A check of oil properties using laboratory analysis methods is expensive. Using the same techniques during service would be extremely difficult. Consequently, oil is seldom analyzed before substitution, which results in oil wasting. This paper shows that in the low frequency range, the temperature coefficient of the dielectric constant of lubricating oils depends on whether the oil is fresh or it has been used. Hence, the change in dielectric constant from ambient temperature to working temperature is a possible sensing method for engine oil condition.

Darko Vasic, Vedran Bilas, Davorin Ambruš
PULSED REMOTE FIELD TECHNIQUE IN FERROMAGNETIC TUBE WALL THICKNESS AND INNER DIAMETER MEASUREMENT

In conventional applications of the remote field eddy current technique, a probe with low frequency sinusoidal excitation is used for measurement of ferromagnetic tube wall thickness. An additional probe with high frequency excitation is required for measurement of the tube inner diameter (electrical caliper). In this paper, this is illustrated with results of finite element analysis. However, the waveform of the pulse driving current and shorter probe length potentially allow the measurement of the inner diameter and the wall thickness with the same probe. We present results of our experiments on ferromagnetic tubes with internal and external defects that confirm applicability of the pulsed remote field technique for measurement of the both quantities.

Arne Troffaes, Patrick Boets, Leo Van Biesen
ON THE CROSSTALK IN TRANSMISSION LINES CAUSED BY SPLICES

A model for the crosstalk between two twisted pairs caused by splices, is proposed. The model will allow the crosstalk to be calculated in any case where splices exist in a transmission line. The expressions are then evaluated by measurements on a lab-produced splice and the total influence of the splices on the total crosstalk is evaluated, in order to see if the crosstalk caused by the splices is relevant compared to the standard crosstalk.

Ryszard Roskosz, Michal Ziólko
MEASUREMENT ACCURACY OF SHORT-CIRCUIT LOOP IMPEDANCE IN POWER SYSTEMS

This paper presents the problems relating to the measurement of power system loop impedance in present day low voltage networks particularly in presence of voltage disturbances. The paper discusses the main sources of loop impedance measurement errors such as: the difference in impedances arguments, transients in tested circuit and the distortion of the voltage waveform in the measurement point. The conditions how to minimize measurement inaccuracy are also given. Example of loop impedance measurement errors are presented in the form of graves for different parameters of the tested circuit.

Domenico Alessandro Lampasi, Luca Podestà
IVI SYSTEMS FOR AUTOMATIC DETECTION OF ELECTRONIC INSTRUMENTS

The aim of this work is the creation of a virtual instrument for the management of an experimental set-up in which the electronic instruments are interchangeable. This is possible using IVI drivers (National Instruments). In this way the software system becomes independent of the chosen hardware.

Tomasz Tarasiuk
INTERPOLATION BASED ON WAVELET COEFFICIENTS FOR FREQUENCY MEASUREMENT

Presented paper concerns the problem of signal period estimation improvement by means of the wavelet coefficients. In particular, the interpolation based on the wavelet coefficient has been proposed for this aim. The method does not require virtually any additional computational power of measurement device, under assumption that the wavelet transform has been implemented for waveform analysis. In the paper results of experimental research have been presented and its merits as well as shortcomings have been discussed.

Roman Szewczyk, Adam Bienkowski, Jacek Salach
INFLUENCE OF STRESSES ON THE PROPERTIES OF FLUXGATE SENSOR WITH PERMALLOY RING CORE

This paper presents results of investigation on influence of stress from the external forces on the sensitivity of the fluxgate sensor with 80% Ni-Permalloy P-80M ring core. Stress was applied in two directions: in the direction of diameter of the ring or in perpendicular direction to the magnetising field in the ring core. The influence of mechanical stress from the external forces on the magnetic properties of this ring core was measured. Then results of this testing were used in computer simulation of the influence of stress on the output signal of the fluxgate. The results confirmed, that stress sensitivity of the fluxgate sensor’s core material must be taken into consideration during the development of such device.

Janusz M. Mosakowski, Andrzej Podgórski
IMPLEMENTATION OF 1/1 OCTAVE AND 1/3 OCTAVE FILTERS IN DIGITAL SIGNAL PROCESSOR

Set of filters is required for the analysis of sound and vibration signals usually composed of different elements. The designing process of so-called 1/1 octave and 1/3 octave digital filters and their implementation in the digital signal processor, working in the real time system, is shortly presented. The obtained exemplary frequency characteristics are given.

Page 935 of 955 Results 9341 - 9350 of 9546