Oral anomalies and dental treatment in a patient with cleidocranial dysplasia (referred to the dental clinic at the age of 40 years) are presented. Five supernumerary teeth were found in the patient: three in the maxilla in the area of molars and two in the mandibula in the area of premolars. Therapy included surgical exposure of impacted teeth in combination with removal of supernumerary teeth.
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.
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.
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.
Authors of the paper present investigation results concerning properties of ADP, ADC and ADNC descriptors which have been obtained during measurements made within three oil transformers and then tested also by other methods (electric and dissolved gas analysis ones). Methodology which makes easier an analysis and identification of acoustic emission signals generated by partial discharges is presented. Results obtained by acoustic emission method have been referred to results coming from other measuring methods.
Investigation results of properties characteristic for acoustic emission signals recorded in two selected power oil transformers are presented. Signals were put to the filtration, whereas components coming from partial discharges have been left. The calculations concerned: phase-time characteristics, averaging phase characteristics, averaging short time Fourier transform spectrograms, amplitude distributions of signals, values of acoustic emission descriptor with acronym ADC. On the ground of calculated basic characteristics and maps of ADC descriptor three areas have been selected on lateral walls of transformer tanks. Acoustic emission signals recorded in these areas were analyzed from the point of view how is influence of propagation path on these properties.
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.
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