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Analysis of Acoustic Signals Interfering Diagnostic Measurements of Electric Power Transformer Tap Changers

100%
Boczar T., Cichoń A., Borucki S., Szczyrba T.
Acta Physica Polonica A
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2013
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vol. 124
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issue 3
387-390
EN
Subject matter of this paper applies to improvement of acoustic emission method used in the diagnosis of on load tap changers of high power transformers. During measurement of acoustic emission signals generated by damages or defects, which can appear in insulation system and in the power transformer tap changers, various forms of noise signals may occur. Interferences occurring during measurements under laboratory and under industrial conditions can be generated either by sources placed inside the studied electric power device or they can be emitted in their immediate vicinity. Sources of interfering signals are physical phenomena of a mechanical, electrical or acoustical nature. Interferences appearing during measurement of acoustic emission pulses generated by electrical discharges and other types of defects that overlap the measured waveforms may result in their distortion. As part of the research conducted, the results of which are presented in this paper, following was subjected under consideration: measurements of acoustic noise signals generated by partial surface discharges occurring on support and bushing insulators were performed.
2
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Influence Estimation of the Voltage Value on the Measurement Results for the Optical Radiation Generated by Partial Discharges on Bushing Isolator

100%
Frącz P.
Acta Physica Polonica A
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2011
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vol. 120
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issue 4
604-608
EN
The subject area of the paper concerns determination of possibility and application scope suggestion for the optical spectrophotometry method in the linear isolators diagnosis. Measurements results of the optical radiation emitted by partial discharges generated on a model of bushing isolator, which was placed in the air, are presented in the paper. Recording was done by use of a spectrophotometer that enabled for measurement of optical radiation in the range from 250 to 1700 nm. The main aim of laboratory research works performed was to estimate the influence of the supply voltage value changes in range from 0 to 60 kV on the intensity and character of the optical radiation spectrum emitted by surface partial discharges occurring on the ceramic insulating surface of the bushing isolator. In the scope of research works, analysis of voltage value changes influence on the gathered spectra was performed while its accretion and decrease was investigated. Furthermore, the measurements and analysis performed enclose the influence estimation of the time, when the voltage was attached to the high voltage electrode, on the proceeding of the optical phenomena connected with generation of surface partial discharges. In addition a comparative analysis of measurements results gathered for two designed and implemented models of bushing insulators, which differ in geometric dimensions, was performed.
3
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The Application of Double-layer Curtains for Shaping Acoustics of Concert Halls

100%
Pilch A., Karlińska A., Snakowska A., Kamisiński T.
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vol. 125
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issue 4A
A-113-A-116
EN
Requirements concerning adjustment of acoustical parameters are nowadays more and more frequently numbered among design assumptions adopted for newly constructed concert halls and other auditoriums planned to play different functions. Investors usually require that the newly designed interiors can be used for such different purposes as playing orchestral music, performing theatre spectacles, screening movies, or holding lectures. This means the necessity to undertake studies on new technologies allowing to excert effective control over acoustics of multipurpose auditoriums. This paper proposes to use acoustic curtains as an effective means of modification of acoustic absorptivity of rooms. A design solutions for such curtains is described together with basics of the theory allowing to predict their acoustic properties. Results of sound absorption coefficient calculations performed for selected systems on the grounds of airflow resistivity values assumed for the used fabrics are verified by means of results of measurements performed in the impedance tube. It is proven that double-layer curtains show more balanced sound absorption characteristics compared to single-layer curtains and therefore represent a more convenient option when used for acoustical adaptation of rooms. Based on model studies, design solutions with double-layer curtains is developed for two concert halls that allow to adjust acoustic properties of the interiors to the required functions.
4
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The Application of the Correlative Analysis and the Regression Function for Determining Correlations οf the Measurement Results of Acoustic Emission Generated by Partial Discharges

100%
Boczar T., Frącz P.
Acta Physica Polonica A
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2009
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vol. 116
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issue 3
281-284
EN
The subject matter of this paper is connected with development of the assessment methods of results obtained at measurements of partial discharges occurring in insulation systems of power transformers using the acoustic emission method. The paper presents the results connected with determining correlation between partial discharge generation voltage and selected descriptors characterizing the emitted signals of acoustic emission in the frequency domain. Authors use the selected descriptors as comparative criteria for recognition of the basic partial discharge forms that may occur in paper-oil insulation of power transformers. The correlation coefficient and regression function were used to determine the correlation degree between the variables under study.
5
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Intraoperative Impedance Measurements for the Evaluation of Perimodiolar Location οf Cochlear Implant Electrode - Own Experience

100%
Stieler O., Karlik M., Szyfter W.
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issue 1
161-163
EN
Evaluation of insertion of a cochlear implant electrode into the cochlea includes radiological techniques: plain X-ray of the skull, cochlear projection (based on Stenvers projection), computer tomography. These methods allow generally postoperative evaluation. During surgery the insertion of the electrode is assessed based on anatomical structures and markers placed on the electrode. The measurement of the electrode impedance is also an important tool. 60 patients implanted with the Contour cochlear implant with pre-shaped electrode were examined. Age o patients: mediana 4.25 (1.5-54.5). Examination includes intraoperative impedance measurement performed in two stages: (1) after the electrode insertion, and (2) after removal of the stylet. Measurements were done in Common Ground (CG) and Monopolar 1 (MP1) stimulation modes. Measurements recorded in two modes and in 3 different parts of the cochlea (apical, middle, basal) were compared. The average difference value (before-after) was for the CG mode: 0.45 kΩ, and for the MP1 mode: 0.39 kΩ. For the CG mode the difference values were: 0.64, 0.44 and 0.28 toward apical part. For the MP1 mode the difference values were: 0.47, 0.43 and 0.27 toward apical part of the cochlea.
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