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Temporally and spatially resolved diagnostics of an electric arc
Holcner, Oldřich ; Šimek, David (referee) ; Kloc, Petr (advisor)
This batchelor thesis "Temporally and spatially resolved diagnostics of an electric arc" deals with the investigation of plasma temperature in an arc formed by evaporation of copper wire. It is an optical method based on determination of temperature from intensity of spectral lines. In this batchelor thesis we explain how spectral lines are formed and how to determine the temperature. In the practical part we process discharge and show the time evolution of temperature at the measured points.
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DC arc extinguishing in low voltage switching devices for critical currents
Fencl, Martin ; Šimek, David (referee) ; Píška, Jakub (advisor)
This bachelor’s thesis deals with DC arc extinguishing for critical currents. The first, theoretical part describes and defines an arc, a DC arc and methods of its extinguishing. The second, theoretical part concerns spectral analysis – specifically, the emission method. Methods of research of extinguishing critical currents are also presented. The practical part consists of two measurements. The first measurement consists of spectrum measuring in time, in conjunction with voltage and current measurements. In the second measurement, the goal was to measure the dependence of arc burning time on voltage and current. The thesis concludes with summary of the results of each individual measurement and their presentation in the wider context.
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Design of MV contactor for railway application
Pala, Lukáš ; Šimek, David (referee) ; Valenta, Jiří (advisor)
In the introduction a traction circuit is analyzed with different types of electric devices. The thesis describes power railway electric circuits, their loads and types of used contactors. Railway standards chapter summarizes requirements of standards for railway contactors. Follows literature focusing on power current switching and power switching devices design. Based on previous, a design procedure is developed for railway MV contactor in accordance with end-user and standards requirements. Thesis closes with pre-designing a railway contactor by calculating electrodynamic forces, heatflow and mechanical components.
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Diagnostics of medium voltage and high voltage circuit breakers
Kapalla, Alexej ; Šimek, David (referee) ; Dostál, Lukáš (advisor)
This semestral work is about high voltage switchgears and their diagnosis. In this work there is part about history of HV switchgears and their dividing. Next part of this work describes diagnostic of HV switchgears VD4 24 ABB and AEG S1-245. In case of HV breaker VD4 there was provided diagnostics of new VD4 and used VD4. The measured values are then compared in the work and the influence of usage of breaker is presented according to his parameters. This work describes measurment of resistance of main contacts, insulation states.
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Design of a 25 kV traction disconnector
Buchta, Martin ; Bušov, Bohuslav (referee) ; Šimek, David (advisor)
This diploma thesis deals with the design of a traction disconnector for 25 kV AC and a rated current of 800 A. The result should be a competitive disconnector that is capable of potential applications on domestic railways and should have parameters that other local manufacturers do not currently offer. This is, for example, electrical strength or the size of the rated current, which is an economic option for most railway lines in the Czech Republic. According to the proposed drawing documentation, the disconnector was assembled and then the selected disconnector parameters were tested. For example, electrical strength tests, short-circuit tests, constant current tests, etc. were performed. The calculated and measured values were compared together. The designed disconnector was financially and technically evaluated on the basis of test results and the construction itself. Finally, some appropriate adjustments were proposed.
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Effect of a switching arc on design of low voltage switchgear
Šimek, David ; Bartlová, Milada (referee) ; Aubrecht, Vladimír (advisor)
The first part of the master thesis is focused on theoretical analysis of the problems of diagnostics of an electric arc physical properties. In the thesis there is shown identification of spectral lines in experimentally measured electric arc spectra. The thesis deals also with energy balance of the arc. Next part of thesis is aimed to theoretical analysis of effects of electric arc on construction materials of low voltage electric apparatuses. The main part of thesis is devoted to experimental measurement of arc radial temperature changes, measurement of cathode temperature and research of electrical arc effect on selected construction materials of low voltage apparatuses.
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Technologies of the electrical apparatuses protyping
Svoboda, Filip ; Kloc, Petr (referee) ; Šimek, David (advisor)
The work focuses on the production of prototypes of electrical devices. The theoretical part contains a structured overview of the historical development of prototype production technologies and description of individual prototyping technologies. The main part of the work is the design of a prototype extinguishing chamber, printing of the chamber and verification of the ability to extinguish the electric arc.
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Reducing transformer inrush
Zoufalý, Marek ; Bušov, Bohuslav (referee) ; Šimek, David (advisor)
In this thesis is described the function and design of the transformer designed on ferromagnetic core, composed of transformer sheets. It is explained a transient inrush current of the transformer. In this work is inserted voltage and current waveforms, designed printed circuit board, serving to reduce the inrush current.
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Diagnostics of current path of high-current apparatuses
Váša, Lukáš ; Bušov, Bohuslav (referee) ; Šimek, David (advisor)
Bachelor’s thesis is focused on the theoretical analysis of methods of technical diagnostics with focus on high-current devices. An overview of the methods used in technical practice is elaborated. In addition, the thesis deals with the strain of current carrying path, subsequently the work focuses on the thermal stress of parts of the current carrying path and its temperature rise. Methods of diagnostics by measuring transient resistance and methods of measurement of temperatures are described and each of the methods’ advantages and disadvantages are stated. The practical part is focused on the diagnotics of the switch disconnector and the disconnector by measurement of the transient resistances of all contacts of the current carrying paths and the following measurement and evaluation of temperature rise of the components by thermal imaging camera. Adjustments to the disconnector leading to financial savings are suggested on basis of these measurements.
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Remanent magnetism of electromagnets of DC contactors
Horký, Jakub ; Píška, Jakub (referee) ; Šimek, David (advisor)
The master thesis is focused on a remanent magnetism of electromagnets of DC contactors. In the first part of the thesis deals with the formation of a magnetic field in different kinds of materials, description of their magnetization and sorting. The next part is focused on the principle and history of an electromagnet. Negative effects and remanent induction of the contactor are described in the end of the theoretical part. The second part is a practical part. First, the reaction times were measured on a pair of DC contactors. Using the obtained data, an electronic circuit was designed to minimize the difference in switching times of the given DC contactors.
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