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Dielectric Properties of Vegetable Oils for Electrical Engineering
Spohner, Milan ; Mejzlík,, Miroslav (referee) ; Mentlík, Václav (referee) ; Liedermann, Karel (advisor)
The dissertation thesis deals with the analysis of prospective environmentally compatible electrical insulating fluids for electrical engineering in relation to their chemical structure. The thesis starts with the overview of the current state of the art and of the latest trends in the use of synthetic and biodegradable natural oils. In the experimental part were studied these oils: mineral oils, rapeseed oil, sunflower oils, soybean oil, methyl oleate, peanut oil, MCT oil, castor oil and other. Dielectric properties were measured using LRC meter Agilent 4980A including dielectric liquid test fixture Agilent 16452A and also by the Novocontrol Alpha-A analyzer. Electrical properties are presented in the frequency range 10 mHz – 1 MHz range in the temperature interval 253 K to 363 K. The work goes on with the study of the suitability of individual oils for lower temperature, including the impact of the chemical structure and formulation on electrical properties.
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Measurement of HV equipments by electronic bridge.
Kumičák, Ivan ; Pelikán, Luděk (referee) ; Krbal, Michal (advisor)
The main idea of this thesis is measurements of dielectric materials by using a device Tettex. The thesis is about basic physic properties of dielectric materials. The determination of a dielectric material is considered. The behavior of these materials in electrical fields and reasons, those can have an influence on it, are considered as well. In the text are described measuring methods of chosen parameters of dielectric materials by device Tettex and its functional principles. There are an evaluation of measurements, which were done, and a discussion about achieved results.
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The process of decompression in hydraulic systems of forming machines
Havelka, Milan ; Habán, Vladimír (referee) ; Pochylý, František (advisor)
This thesis consists of two main parts. The first part is a theoretical analysis, or a literary research, it is focused on the physical properties of the fluid, which have direct impact on the decompression. The aim of the second part is to evaluate the measurement of the forging valve and subsequently simulate the issue by means of CFD. The first simulations were performed for the maximal valve stroke and used for the CFD solver setup calibration. The subsequent analyses dealt with possible openings of the valve. In the final chapter the theoretical impact of the liquid compressibility and of the undissolved air is discussed. The results of the thesis can prove useful for the new valve setting in hydraulic circuit or for possible geometry modification.
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Dielectric Properties of Vegetable Oils for Electrical Engineering
Spohner, Milan ; Mejzlík,, Miroslav (referee) ; Mentlík, Václav (referee) ; Liedermann, Karel (advisor)
The dissertation thesis deals with the analysis of prospective environmentally compatible electrical insulating fluids for electrical engineering in relation to their chemical structure. The thesis starts with the overview of the current state of the art and of the latest trends in the use of synthetic and biodegradable natural oils. In the experimental part were studied these oils: mineral oils, rapeseed oil, sunflower oils, soybean oil, methyl oleate, peanut oil, MCT oil, castor oil and other. Dielectric properties were measured using LRC meter Agilent 4980A including dielectric liquid test fixture Agilent 16452A and also by the Novocontrol Alpha-A analyzer. Electrical properties are presented in the frequency range 10 mHz – 1 MHz range in the temperature interval 253 K to 363 K. The work goes on with the study of the suitability of individual oils for lower temperature, including the impact of the chemical structure and formulation on electrical properties.
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Measurement of HV equipments by electronic bridge.
Kumičák, Ivan ; Pelikán, Luděk (referee) ; Krbal, Michal (advisor)
The main idea of this thesis is measurements of dielectric materials by using a device Tettex. The thesis is about basic physic properties of dielectric materials. The determination of a dielectric material is considered. The behavior of these materials in electrical fields and reasons, those can have an influence on it, are considered as well. In the text are described measuring methods of chosen parameters of dielectric materials by device Tettex and its functional principles. There are an evaluation of measurements, which were done, and a discussion about achieved results.
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The selected properties mineral and synthetic oils
Vu Tân, Hien ; Pošta, Josef (advisor) ; Pavlů, Jindřich (referee)
The main goal of this thesis is focused on comparing the selected properties of mineral and synthetic oils. For this was used operating monitoring and laboratory experiment and with them was compared properties. At operation was observed oxidation, sulfation, nitration, TAN, TBN and the content of metal elements in the oil. In Laboratory was experimental investigated the effect of increased temperature and change of color , viscosity and lubricity. The theoretical part of the thesis describes the basic of tribology and lubrication engineering, types of lubricants and oil properties and their production and distribution.
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The process of decompression in hydraulic systems of forming machines
Havelka, Milan ; Habán, Vladimír (referee) ; Pochylý, František (advisor)
This thesis consists of two main parts. The first part is a theoretical analysis, or a literary research, it is focused on the physical properties of the fluid, which have direct impact on the decompression. The aim of the second part is to evaluate the measurement of the forging valve and subsequently simulate the issue by means of CFD. The first simulations were performed for the maximal valve stroke and used for the CFD solver setup calibration. The subsequent analyses dealt with possible openings of the valve. In the final chapter the theoretical impact of the liquid compressibility and of the undissolved air is discussed. The results of the thesis can prove useful for the new valve setting in hydraulic circuit or for possible geometry modification.
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