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Dielectric properties of epoxy resins
Matoušová, Klára ; Novák, Vítězslav (referee) ; Kazelle, Jiří (advisor)
This diploma thesis deals with the fundamental properties of epoxide mixtures, as determining of these fundamental properties of epoxide mixtures could in the case of favorable results lead to diminishing the amount of defects in epoxide-embedded instrument transformers. As the influence of effects in the manufacturing process of transformers causing poor quality is very extensit, the biggest emphasis is laid capitally on the influence of the epoxide casting mixture composition. The thesis describes the manufacture technology including used methodics and materials. The compositions of epoxide resins and the mechanisms of their curing. Also, the definitions of fundamental properties of dielectric materials and the description of diagnostic methods used to relative permitivity, dissipation factor and inner resistivity are included. suitable casts of acquired samples were set and dried out within the experimental part, followed by measurement of fundamental electrical properties in temperature and frequency relations. Hereafter a comparison of individual samples and the evaluation of their electrical properties will be carried out.
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Degradation of liquid insulators for high voltage
Komárek, Filip ; Štěpánek, Jaroslav (referee) ; Krbal, Michal (advisor)
This bachelor's thesis deals with measurement of liquid insulators. Mainly it deals with diagnostic tests of transformer oil. Diagnostic tests are needed to identify oil status and to determine the parameters of the oil. The status of the used oil determines its type of degradation and progress of degradation. For the determination of degradation it is necessary to know the composition of the essential oil, to determine how it has changed the structure of the oil and the oil did not contain before use. To determine the basic electrical properties of the oil are used in diagnostic tests such as dielectric strength and dissipation factor. This work is in addition to a summary of diagnostic tests observation of mineral oil with an unknown degree of degradation and behavior of impurities in mineral oil once the electric field.
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Diagnosis of high voltage capacitors for cascade voltage multiplier
Baev, Dmitriy ; Špinka, Jiří (referee) ; Krbal, Michal (advisor)
The main subject of the final thesis is to find a suitable method for measuring the partial discharge (PD) in the dielectric of high-voltage capacitor. In the theoretical part of my thesis contains from the mechanisms of origin and the harmful effects of partial discharge at high voltage insulation of capacitor. It describes the global galvanic method of partial discharge measurement, the principle of cascade voltage multiplier, its main components are high-voltage capacitor and diode, facilities quality measurement of capacitors for voltage multipliers, advantages and disadvantages and principles of HIPOTRONICS DDX-8003 with the pulse discrimination system. In the experimental part of the diploma thesis is familiar with the diagnostics of high – voltage capacitors by means of laboratory measurements on the electronic bridge and with the help of partial discharge measurement system. Design of suitable electrode arrangement is described which eliminates the influence of corona which makes it impossible to measure partial discharges and the dissipation factor (tg ). Analysis data from measurement and determination of quality level, eventual degradation of measured capacitors. The result of this project should be designed the methodology for finding of poor – quality capacitors in order to increase the reliability of the voltage multiplier.
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Electrical properties analysis of epoxy resins with various fillers
Horák, Luděk ; Kazelle, Jiří (referee) ; Frk, Martin (advisor)
Presented bachelor thesis is focused on studying electroinsulating epoxy resin-based sealings. It describes the chemical composition, production, properties and measuring methods of basic electric quantities of these materials. This work also embodies a preparation of composite epoxy resin samples with different kinds of micro-ground siliceous sand as a filling. The samples given are measured on the temperature dependency of relative permitivity, dissipation factor and inner resistivity.
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Inorganic fillers effect on electrical properties of the epoxy resins
Doležel, Tomáš ; Jirák, Josef (referee) ; Frk, Martin (advisor)
This thesis deals with problems of electrical insulation materials based on epoxy composites used in the electronics industry. This thesis is divided into theoretical part focused on composite materials, their technological processing and diagnostics. It also describes dielectric materials, their properties and events taking place in their structure. The experimental section describes the measurement of electrical properties of samples of electrical insulating materials with different types of fillers.
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Properties of liquids based on organic esters
Toulová, Jana ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This master's thesis deals with the electrical insulation fluids used in electronics industry. The analysis of the current state of research and innovations in modern, biodegradable fluids in terms of their use as diagnostics. It is described by the physical nature of polarization and conductivity mechanisms, which are applied in liquids. It was compiled automated workstation for monitoring components of the complex permittivity over a wide temperature range. In the experimental part we analyzed the behavior of liquids selected alternative based on natural esters when exposed to an alternating electric field at various temperatures. Evaluated results are compared with values for conventional mineral oil.
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Insulation system of synchronous and induction motors for 18kV
Šporcr, Viktor ; Vetiška, Vojtěch (referee) ; Ondrůšek, Čestmír (advisor)
Bachelor’s thesis is divided into two separate sections. First part is concentrated on insulation system of high voltage machines impregnated by vacuum pressure impregnation. This part of semester thesis concisely describes the composition of individual components used for construction insulation systems of air and water cooled rotation machines. Second practical part contains evaluation of dielectric resistance of coil set with insulation system designed for voltage level 18 kV. This part contains a short description of used insulations. Further includes a report of dielectric tests of used coil set. This set of coils was tested on following tests. Heating measurement semi conductive tape with infrared camera at impulse voltage. The coils was exposed to impulse voltage for one 100 hours and sinus voltage for one 1000 hours. Before and between, aging was measured value of charge partial discharges and dissipation factor.
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Measurement of dielectric properties of liquid fuels for automotive power units
Redr, Martin ; Čech, Ondřej (referee) ; Chladil, Ladislav (advisor)
This bachelor thesis dealt with measuring of dielectric properties of propellants. The aim of the thesis was to find out differences between dielectric quantities of propellants from various manufacturers and in different proportions of refined to so-called bio-components. The theoretical physical principles of dielectric substances – permittivity and dissipation factor were described. In the thesis the most famous electrical insulation fluids whose dielectric characteristics are similar as propellants were mentioned. Furthermore, the study about dielectric properties of propellants and chosen fuels on the Czech market were mentioned. In the experimental part of the thesis, selected fuel samples at varying frequency and temperature were measured. These results were then evaluated and compared.
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