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Wyświetlanie 1-15 z 26
Tytuł:
Characteristic of Acoustic Signals Generated by Operation of On Load Tap Changers
Autorzy:
Cichon, A.
Fracz, P.
Zmarzly, D.
Powiązania:
https://bibliotekanauki.pl/articles/1493036.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.-s
43.28.Js
Opis:
Possibilities of application of the acoustic method for the on load tab changers diagnosis has been presented in the paper. The analysis of measurement results gathered during research works performed under laboratory conditions has been presented in detail. The registered acoustic signals have been analyzed in time and time-frequency domains. The time domain analysis has been performed by presentation of time runs and their envelopes determined by use of the Hilbert transform. Evaluation of the time-frequency components has been performed by use of the short-time Fourier transform, the discrete and the continuous wavelet transforms.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 585-588
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characteristics of Acoustic Emission Signals Generated by the Contacts of the Selector
Autorzy:
Cichoń, A.
Borucki, S.
Wotzka, D.
Szmajda, M.
Powiązania:
https://bibliotekanauki.pl/articles/1417945.pdf
Data publikacji:
2012-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.-s
43.28.Js
Opis:
An important part of electric power transformer is the on load tap changer which enables for voltage regulation in the network. Due to high level of failure frequency of these devices it is necessary to look for new diagnostic methods which enable for theirs technical state estimation under transformer normal operating condition. Presently at the Electric Power Institute at Opole University of Technology there are works in progress aspiring to determine the application possibility of the acoustic emission method for on load tap changer diagnosis. Results of scientifically-research works aiming to characterize the acoustic emission signals generated by a separated selector are presented in the paper. Measurements have been performed in a setup with a model of on load tap changer type VEL-110-27 from ELIN. Acoustic emission signals generated by the selector have been analyzed in detail. Analysis of the time-frequency components of signals generated by on load tap changer has been carried out with the short time Fourier transform and continuous wavelet transform. Based on the comparison outcome of acoustic emission signals generated by the power changer and by the selector two measuring paths endowed with wide band contact transducers have been proposed for the practical application.
Źródło:
Acta Physica Polonica A; 2012, 122, 5; 804-807
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Application of the Selected Time-Frequency Descriptors Detection of the Acoustic Emission Signals Generated by Multisource Partial Discharges
Autorzy:
Cichon, A.
Powiązania:
https://bibliotekanauki.pl/articles/1795791.pdf
Data publikacji:
2009-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.-s
43.28.Js
Opis:
The paper presents the comparative analysis results of the acoustic emission signals generated by various forms of partial discharges occurring in multisource systems. Modern methods of the signal digital processing: a short-time Fourier transform and continuous and discrete wavelet transforms were applied for the assessment of the results in the time-frequency domain. The acoustic emission signals generated by partial discharges were registered with a WD AH17 contact transducer by the Physical Acoustics Corporation placed on the external part of the tub.
Źródło:
Acta Physica Polonica A; 2009, 116, 3; 290-293
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Investigation on Surface and Electrical Properties of Electrical Discharge Machined AISI D2 Tool Steel
Autorzy:
Durmus, A.
Bayram, A.
Gunes, S.
Akay, S.
Powiązania:
https://bibliotekanauki.pl/articles/1182843.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.-s
81.65.-b
Opis:
The effects of pulse-on duration and finishing operation on the surface roughness and electrical resistivity of AISI D2 tool steel machined by the electrical discharge machining process are investigated. Experimental results indicate that surface roughness increased depending on the pulse-on duration. However, after the specific value, surface roughness is decreased. It can be seen that there are no notable effects of the pulse-on duration on the electrical resistivity, but the resistivity values are affected by the heat treatment and the finishing operation. Also, light microscopy and scanning electron microscopy have been used to study the characteristics of the surfaces.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 515-517
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron Avalanche Statistics
Autorzy:
Ficker, T.
Powiązania:
https://bibliotekanauki.pl/articles/1585038.pdf
Data publikacji:
2009-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.-s
52.80.Dy
52.80.Mg
Opis:
A solution of the long-lasting problem with anomalous population statistics of pre-streamer avalanches has been proposed in the form of a new generalized probability density function.
Źródło:
Acta Physica Polonica A; 2009, 116, 6; 1018-1020
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electric Field Modelling in Gas-Insulated Substation for Analysis of Conditions for Partial Discharge Phenomena
Autorzy:
Florkowska, B.
Zydroń, P.
Jackowicz-Korczyński, A.
Powiązania:
https://bibliotekanauki.pl/articles/1401877.pdf
Data publikacji:
2015-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
51.50.+v
52.80.-s
84.70.+p
41.20.-q
Opis:
The paper refers to diagnostics problems connected with the presence of partial discharges in gas-insulated substation. The basic stimulus for partial discharges generation is local, high value electric field, greater than the inception one. The numerical simulations of the electric field distribution in the part of the gas insulating system and in the vicinity of the metallic protrusion located on high voltage conductor are presented. Such defects are often present in SF₆ insulated constructions and are the cause of a local increase of the electric field. Theoretical analysis of physical mechanism of partial discharges initiation and development in the case of micro-needle type defects is described.
Źródło:
Acta Physica Polonica A; 2015, 128, 3; 319-325
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anusual Application of Partial Discharges to Diagnose of High Voltage Power Transformers
Autorzy:
Gacek, Z.
Szadkowski, M.
Malitowski, G.
Witos, F.
Olszewska, A.
Powiązania:
https://bibliotekanauki.pl/articles/1493101.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Le
52.80.s
07.50.Hp
Opis:
The article contains information on research carried out in Electric Faculty of Silesian University of Technology, made at test stations and aimed at diagnosis how is actual technical state of high voltage power oil transformers. Opinion on a state of transformers is based on analysis results of partial discharge measurements. Authors use simultaneously: electric, acoustic and dissolved gas analysis method. Applied acoustic method is the original own one. Non-conventional application of electric method is proposed, too. In the frame of chosen methodology the partial discharges are measured and next calculations of quantities describing partial discharges within particular methods are carried out in order to describe phenomena commonly for electric and acoustic method. Information sources about level and kind of partial discharges are measurement results obtained from electric method whereas information on places where partial discharges appear is contained in measurement results coming from acoustic method. Authors present selected application results of such a combined measuring method.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 609-615
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ion and Electron Beam Induced Luminescence οf Rare Earth Doped YAG Crystals
Autorzy:
Gawlik, G.
Sarnecki, J.
Jóźwik, I.
Jagielski, J.
Pawłowska, M.
Powiązania:
https://bibliotekanauki.pl/articles/1504113.pdf
Data publikacji:
2011-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.60.Hk
52.59.Bi
79.20.Rf
61.80.Lj
41.75.Ak
41.75.Cn
61.72.S-
61.72.-y
29.40.-n
77.84.Bw
79.60.Ht
87.53.Bn
78.55.-m
78.60.-b
77.55.Px
77.55.-g
25.40.Lw
Opis:
The aim of this work was the evaluation of ion-beam induced luminescence for the characterization of luminescent oxide materials containing rare earth elements. The yttrium aluminium garnet epilayers doped with Nd, Pr, Ho, and Tm atoms were used. The ion-beam induced luminescence spectra were excited using 100 keV $H_2^{+}$ ion beam and were recorded in the wavelengths ranging from 300 nm up to 1000 nm. The separate parts of the surface of the same samples were used for ion-beam induced luminescence and cathodoluminescence experiments. Cathodoluminescence spectra have been recorded in the range from 370 nm up to 850 nm at 20 keV e-beam in scanning electron microscope equipped with a grating spectrometer coupled with a photomultiplier. The observed narrow ion-beam induced luminescence lines can be ascribed to the well known radiative transitions in the rare-earth ions in the YAG crystals. The cathodoluminescence spectra reveal essentially the same emission lines as ion-beam induced luminescence. The decrease of the ion-beam induced luminescence lines intensity has been observed under the increasing ion fluences. The ion-beam induced luminescence may be used for characterization of transparent luminescent materials as an alternative method for cathodoluminescence and can be especially useful for observation of ion-beam damage formation in crystals.
Źródło:
Acta Physica Polonica A; 2011, 120, 1; 181-183
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measuring Picosecond Flashover in Closing Coaxial Spark Gap Switch
Autorzy:
Klüss, J.
Hällström, J.
Powiązania:
https://bibliotekanauki.pl/articles/1807883.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
51.50.+v
52.70.Gw
52.80.-s
Opis:
Flashover voltage and picosecond risetime of breakdown in pressurized $SF_{6}$ gas is studied on a coaxial line. Gas pressure is varied from 1 to 19 bar. The homogeneous field gap has an opening from ca. 0.2 to 0.9 mm, and flashover voltages reach 120 kV. Measurements are performed using a D-dot probe with 16 to 20 GHz real-time oscilloscopes and a 50 GHz sampling oscilloscope. Measured risetimes are down to ca. 50 ps, and the dependence of voltage collapse on gas density and electric field between the electrodes is reported. Integrity of data is analyzed and experimental results are compared with present theory found in literature and previous results measured with alternative real-time systems.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 1004-1006
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Uncertainty Evaluation of Measurement Data Processing Algorithm Based on Its Matrix Form
Autorzy:
Konopka, K.
Topór-Kamiński, T.
Powiązania:
https://bibliotekanauki.pl/articles/1493241.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.-s
77.22.Jp
84.70.+p
Opis:
Data processing algorithms are important parts of modern measurement systems. These algorithms are often delivered to the user as complex program and their numerical structure is not known. Therefore also influence of algorithm on processed data accuracy is not known. One of the methods to evaluate uncertainty propagation through algorithm is based on matrix form of algorithm. Coefficient matrix of algorithm represents its numerical operations and it is a basis to algorithm accuracy evaluation. The paper presents a method how to identify this coefficient matrix when algebraic form of the algorithm is known or is difficult to use. Identified matrix form of algorithm is then used to estimate uncertainty propagation through exemplary algorithms. Results are compared with experiments.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 666-670
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurements of Cu Atoms Diffusion Coefficients in He and Ne - Optimalisation of a Novel Method
Autorzy:
Kwaśniewski, W.
Dzieciołowski, K.
Adamowicz, T. M.
Powiązania:
https://bibliotekanauki.pl/articles/2035632.pdf
Data publikacji:
2002-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.55.Lt
42.60.Lh
52.80.-s
Opis:
A novel method based on two-pulse excitation of a hollow cathode discharge to determine metal atoms diffusion coefficients in noble gases was tested in Cu-He and Cu-Ne systems. The excitation conditions such as time duration of the discharge current pulses and configurations of the hollow cathode discharge were checked. Measurements carried out over the wide range gas pressures allowed obtaining the Cu atoms time-decay curves from which the diffusion coefficients were calculated. The values for Cu atom diffusion coefficients of 570 and 310 cm$\text{}^{2}$ s$\text{}^{-1}$ mbar in He and Ne, respectively were in a good agreement with earlier reported data achieved by using the absorption spectroscopy method. The diffusion coefficient of Cu in $\text{}^{3}$He, the lighter isotope of helium, was also found to be 670 cm$\text{}^{2}$ s$\text{}^{-1}$ mbar that agreed well with the kinetic theory of gases. To authors believe this value was not reported previously.
Źródło:
Acta Physica Polonica A; 2002, 102, 6; 747-757
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of Deformation Processes within Power Oil Transformers Using Maps of ADC Descriptors in Selected Frequency Bands
Autorzy:
Olszewska, A.
Powiązania:
https://bibliotekanauki.pl/articles/1399392.pdf
Data publikacji:
2013-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.40.Le
52.80.-s
43.60.-c
43.58.Ta
77.22.Jp
84.70.+p
Opis:
The paper presents identification results of deformation processes within power oil transformers where - according to dissolved gas analysis investigation results - partial discharges took place. The original method worked out for analysis of acoustic emission signals recorded within tested transformer and particularly maps of ADC descriptors have been applied. Analysis has been carried out within chosen frequency bands in order to distinguish signals coming from different sources (among other things partial discharges, Barkhausen's effect, circulation of the oil, and outer acoustic sources). One source of partial discharges has been identified within the tested transformer as a result of analysis of acoustic emission signals.
Źródło:
Acta Physica Polonica A; 2013, 124, 3; 525-528
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Location and Identification of Acoustic Signals Recorded in Power Oil Transformers within the Band of 20-180~kHz
Autorzy:
Olszewska, A.
Witos, F.
Powiązania:
https://bibliotekanauki.pl/articles/1493254.pdf
Data publikacji:
2011-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.-s
77.22.Jp
84.70.+p
43.40.Le
43.60.Lq
Opis:
Emission acoustic signals, recorded in investigated power oil transformers, have been analyzed in the time, frequency and time-frequency domain. Analysis of each signal has been started by filtration within selected frequency band and subsequently the following quantities have been calculated: spectral power density, phase-time characteristic, averaging phase-time characteristic, short-time Fourier transform spectrograms, signal amplitude distributions, descriptors with acronyms ADC and ADP and thereafter maps of descriptors on lateral walls of transformers can be carried out. Frequency bands applied in order to filtration have been chosen in such a way so that signals coming from different sources (among other things from partial discharges, Barkhausen's effect, oil circulation and outer acoustic disturbances) can be differentiated. The sources have been localized using maps of descriptors calculated for selected frequency bands. The fundamental properties of obtained signals have been determined. Such properties describe: partial discharges, Barkhausen's acoustic effect and other acoustic interferences.
Źródło:
Acta Physica Polonica A; 2011, 120, 4; 709-712
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Location of Partial Discharge Sources and Analysis of Signals in Chosen Power Oil Transformers by Means of Acoustic Emission Method
Autorzy:
Olszewska, A.
Witos, F.
Powiązania:
https://bibliotekanauki.pl/articles/1418066.pdf
Data publikacji:
2012-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.-s
77.22.Jp
84.70.+p
43.40.Le
43.60.Lq
Opis:
The original system useful for analysis of signals recorded during investigations of partial discharges within power oil transformers by means of acoustic method is presented. This method includes the basic and advanced analysis of recorded data. In the frame of basic analysis of data recorded signals undergo filtration in chosen frequency bands and next the analysis is made - in domain of time, frequency, time-frequency and discrimination threshold. In the frame of advanced analysis of data the amplitude distributions of acoustic emission signals and the acoustic emission descriptors (defined by the authors) are calculated in order to outline maps of acoustic emission descriptors on lateral walls of a transformer; it is a base for location of sources of partial discharges by means of the original method consisted in determination of advance degree of a signal. Results of this analysis, for signals recorded in two chosen transformers with identical construction (partial discharge occurred only within one of them), are presented in the paper. The source of partial discharge, situated within oil near transformer tank, was localized; the revision confirmed this result. Properties of recorded emission acoustic signals at chosen measuring points situated on the tank, in function of distance between the partial discharge source and measuring points, are presented.
Źródło:
Acta Physica Polonica A; 2012, 122, 5; 921-926
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synchronization Study and Introductory Experiment οf Laser-Triggered Surface Flashover in Voltage Pulse
Autorzy:
Pan, R.
Wang, J.
Sun, Y.
Sun, G.
Yan, P.
Zhang, D.
Powiązania:
https://bibliotekanauki.pl/articles/1807974.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.-s
51.50.+v
Opis:
With the aim of studying the characteristics of laser-triggered surface flashover in voltage pulse, synchronization problem of laser pulse and voltage pulse should be solved. A single/double harmonic, with wavelength λ of 1064/532 nm, Q-switched Nd:YAG laser is used to trigger the surface flashover. The synchronization problem is solved using a self-made digital delay/pulse generator. The delay time and jitter of Marx's trigger input and output, Marx's trigger output and Marx's output, laser input and output are respectively measured. Based on the result of the delay time and the timing sequence of the laser triggering system, the synchronization of laser pulse and voltage pulse is obtained through adjusting the channel delay time of digital delay/pulse generator. In addition, introductory experiment of laser-triggered surface flashover is carried out using the flat electrodes and columned insulators.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 1167-1169
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 26

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