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Selected Problems of Diagnosis of Insulation Systems for Rotating Electrical Machines
Pavlík, Josef ; Radek,, Szabó (referee) ; Singule, Vladislav (referee) ; Hammer, Miloš (advisor)
This dissertation thesis deals with the measurement of insulation resistance for rotating electrical machines and polarization indices calculated from them. The first part contains a short theoretical introduction, methods of measurement and basic formulas for calculations. The second part discusses the results obtained in laboratory measurements in both the model and the real coil of high voltage machine. There are also elucidated some of the principles and causes of some phenomena with which the measurement of insulation resistance is encountered. The third part deals with the results of measurements on real machines. There are mainly discussed the dependences of insulation resistance and polarization index on the influences that occur in measurements such as temperature measured insulation, moisture in the insulation, but also the influence of measuring instruments on the measured values. It is also expressed how much these factors affect the measurement results. In addition, this part deals with some other influences that have a negative affect on the measurement of insulation resistance. There is processed a new methodology for measuring insulation resistence in the fourth part of this thesis. The need to develop a metodology of measuring is based on the needs of engineering practice, where is considerable inconsistency of measurement in the present time. Measurement, and often performed on the same machine, are not nowadays often comparable, because measurements are not met even the basic rules resulting from the findings of research and development, which were discovered in the last few decades. Measurement of insulation resistance in our nowdays methodology stagnated on the level of the seventies of 20th century. For this reason, we have developed a new methodology of measurement that takes into account all significant influences affecting the measurement. The purpose of the methodology is to ensure full repeatability and comparability of measurements not only on the same machine but on machines of the same type, in optimal cases, the machines of different types. There are the chapters "The objectives of the work" and "Conclusion" the part of the work. A very important chapter is "The contribution of thesis", which summarizes the original results of this work and results, the use of which is expected in engineering practice.
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The use DC electrical method in diagnostics of insulating materials
Volf, Michal ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
In this work describe to the Dielectric relaxation spectroscopy for the evaluation of the actual status of insulation systém. The used methods of quantifying the dielectric response in time domain are polarization-depolarization current and recovery voltage measurement and in frequency domain the loss factor and the complex capacitance measurement. Influence of thermal ageing and temperature dependences of charge and dischage currents are observed.
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Temperature and humidity influence on insulation resistance of electric motors
Fiala, Petr ; Vetiška, Vojtěch (referee) ; Ondrůšek, Čestmír (advisor)
The bachelor‘s thesis studies the effects of temperature and relative humidity on the insulation resistance of electric motors and their polarization index. The first chapter describes measuring principle of insulation resistance, measured objects, used measuring instruments and actual environmental conditions. The second chapter defines the basic requirements of insulation systems and there is especially solved evaluation of the measurement of individual parts of motors and calculation of polarization index. Third chapter discusses the influence of temperature and relative humidity on insulation resistance, there are formulated general preconditions and after using climate chamber there are presented measurement results on real motors in the industrial practice.
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Risk Modelling in Engineering Applications
Konečný, Antonín ; Karpíšek, Zdeněk (referee) ; Popela, Pavel (advisor)
The diploma thesis focuses on risk modelling in engineering applications. The knowledge obtained from statistical methods of operational research, specifically regression analysis, is used. Electrical quantities measured on the stator winding of an electrical machine (generator) are analyzed. Regression analysis and statistical hypothesis testing is performed in Statgraphics software. The success results of the regression analysis for risk reduction are documented in detail and the regression curves are visualized in graphs. Conclusions and recommendations for each generator, as well as general ones, are formulated.
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Risk Modelling in Engineering Applications
Konečný, Antonín ; Karpíšek, Zdeněk (referee) ; Popela, Pavel (advisor)
The diploma thesis focuses on risk modelling in engineering applications. The knowledge obtained from statistical methods of operational research, specifically regression analysis, is used. Electrical quantities measured on the stator winding of an electrical machine (generator) are analyzed. Regression analysis and statistical hypothesis testing is performed in Statgraphics software. The success results of the regression analysis for risk reduction are documented in detail and the regression curves are visualized in graphs. Conclusions and recommendations for each generator, as well as general ones, are formulated.
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Comparison of individual development of oocytes maturation of sterlet (Acipenser ruthenus) females during the prespawn period at different temperature conditions
KNOWLES, Jindřiška
The aim of presented work was a study of the effect of temperature on the development of mature oocytes of sterlet during prespawn period. At the turn of 2013 and 2014 was conducted our experiment with females of sterlet. Experimental fish were divided into two main groups. The first group was exposed to the heated water and a second group was kept in natural water temperature. Four biopsies were carried out during attempt. The samples were measured, and then was calculated oocyte polarization index (PI). For more accurate results processing fish were divided into two subgroups within both groups. 1st subgroups had at first biopsy PI 12.5 % and 2 subgroups PI> 12.5 %. In less mature females the effect of temperature was statistically significant (p < 0.05) while in more mature females the opposite was true (p > 0.05). From a total assessment follows that the temperature had no significant importance for the rate of oocytes maturation (p > 0.05). Experimental results indicate that the heating method can be used to accelerate the maturation especially in less mature fish and for synchronization spawning.
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Temperature and humidity influence on insulation resistance of electric motors
Fiala, Petr ; Vetiška, Vojtěch (referee) ; Ondrůšek, Čestmír (advisor)
The bachelor‘s thesis studies the effects of temperature and relative humidity on the insulation resistance of electric motors and their polarization index. The first chapter describes measuring principle of insulation resistance, measured objects, used measuring instruments and actual environmental conditions. The second chapter defines the basic requirements of insulation systems and there is especially solved evaluation of the measurement of individual parts of motors and calculation of polarization index. Third chapter discusses the influence of temperature and relative humidity on insulation resistance, there are formulated general preconditions and after using climate chamber there are presented measurement results on real motors in the industrial practice.
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Selected Problems of Diagnosis of Insulation Systems for Rotating Electrical Machines
Pavlík, Josef ; Radek,, Szabó (referee) ; Singule, Vladislav (referee) ; Hammer, Miloš (advisor)
This dissertation thesis deals with the measurement of insulation resistance for rotating electrical machines and polarization indices calculated from them. The first part contains a short theoretical introduction, methods of measurement and basic formulas for calculations. The second part discusses the results obtained in laboratory measurements in both the model and the real coil of high voltage machine. There are also elucidated some of the principles and causes of some phenomena with which the measurement of insulation resistance is encountered. The third part deals with the results of measurements on real machines. There are mainly discussed the dependences of insulation resistance and polarization index on the influences that occur in measurements such as temperature measured insulation, moisture in the insulation, but also the influence of measuring instruments on the measured values. It is also expressed how much these factors affect the measurement results. In addition, this part deals with some other influences that have a negative affect on the measurement of insulation resistance. There is processed a new methodology for measuring insulation resistence in the fourth part of this thesis. The need to develop a metodology of measuring is based on the needs of engineering practice, where is considerable inconsistency of measurement in the present time. Measurement, and often performed on the same machine, are not nowadays often comparable, because measurements are not met even the basic rules resulting from the findings of research and development, which were discovered in the last few decades. Measurement of insulation resistance in our nowdays methodology stagnated on the level of the seventies of 20th century. For this reason, we have developed a new methodology of measurement that takes into account all significant influences affecting the measurement. The purpose of the methodology is to ensure full repeatability and comparability of measurements not only on the same machine but on machines of the same type, in optimal cases, the machines of different types. There are the chapters "The objectives of the work" and "Conclusion" the part of the work. A very important chapter is "The contribution of thesis", which summarizes the original results of this work and results, the use of which is expected in engineering practice.
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