Wyniki wyszukiwania - BazTech

1

Prototype measurement system for localization of partial discharges sources – microphone array

Polak F., Sikorski W., Siodła K.

Computer Applications in Electrical Engineering

|

2015

|

Vol. 13

209--219

EN

This paper presents a prototype measurement system, that will be used for localization of acoustic emission sources originating from partial discharges (PD). It is based on sensor arrays technology and direction of arrival estimation algorithms. Acoustic signals will be received with a universal linear array (ULA) of sensors, wherein the sensory elements are microphones operating in the audible frequency range. For the estimation of the direction of arrival of these signals conventional beamforming algorithm is used which has also been described theoretically. Ultimately, the system will be used to determine the direction of arrival of the acoustic signal generated by the insulation defect, which is corona discharge.

2

Wpływ mikroklimatu na aktywność wyładowań niezupełnych w maszynach elektrycznych w warunkach eksploatacji przemysłowej

Plutecki Z., Szymaniec S.

Energetyka

|

2012

|

nr 12

791-798

PL

Przedstawiono wyniki analiz wpływu mikroklimatu na aktywność wyładowań niezupełnych w maszynach elektrycznych. Wyznaczono korelacje wzajemne określającej wpływ każdego parametru mikroklimatu na emisję wyładowań niezupełnych. Wyznaczone według metody Pearsona wartości współczynników korelacji wzajemnej dostarczają informacji o jakości tych zależności. Istnieje możliwość redukcji emisji wnz poprzez zapewnienie temperatury i wilgotności powietrza sprzyjających obniżeniu aktywności wyładowań niezupełnych. Dla badanej maszyny zostały określone zalecane parametry mikroklimatyczne, przy których emisja wnz nie powinna przekroczyć 25% obecnego zakresu zmian aktywności wnz. Zapewnienie warunków mikroklimatycznych w podanym zakresie, zdaniem autorów, pozwoli znacznie wydłużyć czas bezawaryjnej eksploatacji silnika. Zwrócono uwagę na prawidłowe funkcjonowanie układu chłodzenia maszyn elektrycznych. Na podstawie przeprowadzonych badań wykazano, że w pomieszczeniach pracujących maszyn dochodzi do intensywnych zjawisk cieplno-przepływowych, będących skutkiem pracy silnika i oddziaływań zewnętrznych. Ocena stopnia starzenia się izolacji uzwojeń maszyn elektrycznych przy wykorzystaniu metody wyładowań niezupełnych wymaga zachowania poprawności metodologicznej.

EN

Presented are analyses results of microclimate influence on PD activity in electric machines. Determined are mutual correlations characterizing influence of every microclimate parameter on PD emission. The determined, by Pearson’s method, values of mutual correlation coefficients provide us with informations on quality of these dependencies. There is a possibility of PD emission reduction by providing temperature and atmosphere humidity on the level favourable for reduction of PD activity. For the tested machine there were determined the advisable microclimate parameters with which the PD emission should not exceed 25% of the present range of PD activity changes. Providing of microclimatic conditions in the given range will, in the Authors’ opinion, considerably allow to elongate failure-free operating time of the motor. Attention is paid to proper functioning of electric machines cooling systems. There is proved, on the basis of the carried out tests, that in rooms where machines work it comes to intensive thermal and flow phenomena as a result of motors work and external influences. Evaluation of electric machines insulation ageing degree with the use of PD method requires keeping methodological correctness.

3

The analysis of the acoustic emission signals generated by multisource partial discharges

Boczar T., Borucki S., Cichoń A.

Molecular and Quantum Acoustics

|

2008

|

Vol. 29

11-20

EN

The paper presents research work results aiming at determining the possibilities of recognizing defects of paper-oil insulation systems based on the registered acoustic emission (AE) signals generated by multisource partial discharges (PDs) of various types. The investigations were carried out in a model system in which multisource electrical discharges were generated with two modeling spark-gaps: one spark-gap in the surface system and the other in the multipoint-plane system. The aim of the research carried out was to confirm the suitability of the AE method for diagnosing the insulation condition of high-voltage power appliances, in which multisource PDs may occur. The signal analysis was carried out in the frequency and time-frequency domains. The paper presents a comparative analysis of the AE signals registered from the point of view of the identification possibilities of the particular PD types.

4

Influence of the oil layer thickness on suppression of higher frequencies of the acoustic emission signals generated by partial discharges

Borucki S., Boczar T., Cichoń A., Lorenc M.

Molecular and Quantum Acoustics

|

2008

|

Vol. 29

21-26

EN

The subject matter of this paper refers to the assessment of the influence of the oil layer thickness on suppression of the acoustic emission (AE) signals generated by partial discharges (PDs) developing in paper-oil insulation of power appliances. The paper presents laboratory research results referring to the analysis of suppression of the AE signals frequency band depending on the thickness of AE pulses (oil layer) propagation channel. The measurements of the AE signals generated by SPDs were taken with two wide-band hydrophones type TC4038 by Reson company. One of the hydrophones was placed close to the PD source and the other measuring sensor was shifted along the transformer tub model.

5

Application of signal processing elements for the characteristics of acoustic emission pulses generated by partial discharges

Boczar T., Borucki S., Cichoń A., Lorenc M.

Molecular and Quantum Acoustics

|

2007

|

Vol. 28

23-38

EN

The subject matter of this paper refers to the issues connected with the application of modern numerical methods in processing and analysis of the signals measured by the acoustic emission method (AE) during high-power experiments carried out in laboratory conditions in the setups modelling basic partial discharge forms (PDs). The detailed cognitive aim of the research work was determining the possibilities and the application range of the short time Fourier transform (STFT) and wavelet transform in the analysis of the AE pulses generated by basic PD forms that can occur in oil insulation systems of such appliances as transformers, measuring transformers, bushing insulators, switchgears, and power condensers. The time – frequency analysis was carried out for the particular PDs from the point of view of determining differences and indicating common features for the frequency structures determined, for the positive and negative voltage polarizations separately. The research concentrated mainly on the following types of PDs: point-plane, multipoint-plane, multipoint-plane with a layer of pressboard, surface, generated in gas bubbles and on the indeterminate-potential particles moving in oil. In calculations using wavelet transformations basic types of analyzing functions, the so-called basic wavelets, were applied. When determining amplitude spectrograms of the AE pulses measured various types of observation windows were used. Moreover, for the approximation runs determined and for the particular details the autocorrelation functions (ACF) were calculated, and the probability density functions (PDF) were calculated to determine statistical properties. Also, frequency spectrum runs for the AE pulses measured and the diagrams corresponding with the details analyzed, which visualize the size of energy transferred at the particular decomposition levels, were determined. The paper presents the results of measurements and analyses of the AE pulses generated by the PDs in oil in the multipoint-plane with a layer of pressboard system.

6

Application Possibilities of The Statistical Analysis and Digital Processing Methods in the Characteristics of the AE Signals Generateg by PDs

Boczar T.

Molecular and Quantum Acoustics

|

2002

|

Vol. 23

63-82

EN

The subject matter of this paper refers to the improvement of the AE method used in the measurements of PDs occuring in oil insulation systems of power appliances. The deatailed subject matter, however, is connected with presenting appilacion possibilities of the descriptive statistics indicators, statistical analysis, and the methods of digital signal processing in the characterstics of the AE pulses generated by basic PD forms.