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Investigation on the Interaction between Construction Materials and Switching Arc in Low Voltage Switching Devices
Šimek, David ; Slavíček, Pavel (referee) ; Mindl,, Pavel (referee) ; Kloc, Petr (advisor)
The doctoral thesis is focused on the interaction of construction materials and the switching arc in low voltage switchgear. An issue of selected low-voltage electrical devices, electric arc in electrical devices, and its diagnostics using optical emission spectroscopy and high-speed video are discussed at the theoretical level. The main part of the work is an experimental examination of samples of selected high-performance industrial plastics. A series of tests of resistance to an electric arc were performed on these plastics. The electrical parameters of the switching process, the weight losses of the material of the quenching chambers when applying various power parameters were evaluated from the experiments. The empirical equations were determined for the calculation of the loss of individual materials in a specific configuration. Furthermore, the influence of the used material on the behavior of the electric arc in the extinguishing chamber made of these plastics was investigated. A high-speed video was recorded, the time evolution of the pressure inside the chamber, the electrical parameters of the arc, and the time-resolved evolution of the radiation spectra were measured using atomic emission spectroscopy in these measurements. The relative composition of the plasma was identified from the radiation spectra, and the time evolution of the relative contamination of the discharge area by the main contact material and the selected vapors of the used plastics was created. The last important parameter of the electric arc is its temperature, which was also calculated from the radiation spectra. A comparison of individual plastics and their applicability for applications in contact with electric arc was performed based on the obtained data.
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Campaign of the Czechoslovak National Socialist Party in the 1946 Elections
Šimek, David ; Shavit, Anna (advisor) ; Konrádová, Marcela (referee)
The bachelor thesis aims to present the campaign of the Czechoslovak National Socialist Party (CNSP) in the 1946 Elections, to which it also provides relevant theoretical and historical context. The post-war period in Czechoslovakia (1945-1948) is most often examined from the point of view of the Czechoslovak Communist Party and its gradual takeover of power in the state, culminating in February 1948. Other political parties of this period thus often find themselves overshadowed, despite their important role in the afterwar renewal of political and social life. This work therefore hopes to enrich the discourse with the CNSP perspective. The first part deals with theoretical background of political communication (examining the term propaganda) and with development of party organization and election campaigning. Emphasis is placed on concepts that approach the issues from a wider historical perspective, thus allowing an analysis of models and patterns of political practice which are in today's world mostly obsolete. The second part describes the political and social context of the 1946 Elections. The third part is dedicated to the Czechoslovak National Socialist Party, its origins, history and leading candidates in the 1946 elections. Subsequently, the main aspects of the party's election campaign...
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Temporal Development Of Relative Ablation Of Plastics In Miniature Circuit Breaker During Switching Process
Simek, David
The paper is focused on an ablation of plastic materials in contact with an electric arc inside the electrical apparatus during the switching process. It is possible to obtain temporal development using method based on optical emission spectroscopy. The emission spectra were taken during the switching process. The hydrogen alpha spectral line of Balmer series was used as an indicator for evaluating of plastics ablation. Complications connected with the measurements are discussed. The main part of the paper deals with a temporal development of relative concentration of a hydrogen in plasma inside the miniature circuit breaker. Atomic spectral lines database of National Institute of Standards and Technology was used as a spectral data source for evaluation.
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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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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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Experimental Measurement Of Radial Temperature Distribution Of DC Arc
Šimek, David
The paper is focused on an electric arc spectroscopy diagnostics related to electric low voltage apparatuses. Measurement of radiation spectra of the electric arc burning between carbon electrodes with cooper admixture is presented. Cooper has a lot of suitable atomic spectra lines for calculation purposes. The problems connected with the measurements are discussed. The main part of the paper deals with a calculation of radial temperature distribution of the arc. Abel inversion was used to extracts the radial (2D) distribution from a one-dimensional projection measurement. Atomic lines database of National Institute of Standards and Technology was used as a spectral data source for the calculations.
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Control of Low Voltage Contactor by calculation and measurement
Veselý, Matěj ; Šimek, David (referee) ; Bušov, Bohuslav (advisor)
The bachelor project deals with controlling mean parametres of low voltage contactor by calculation and measurement. Deals more specifically with calculation of the applied electrodynamic forces on the contactor's movable contact, the determination of the minimum compressive force on the contactor's movable contact and the design of the contactor trip system. It also deals with calculation of heating of the current-carrying path on contactor and its following check by measuring.
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Design of DC electromagnet
Mayer, Aleš ; Bušov, Bohuslav (referee) ; Šimek, David (advisor)
This bachelor thesis deals with electromagnets and measurements on them. There is described the history of discovery of electromagnets, the principle of operation, their construction, and classification according to various criteria. More detailed descriptions of individual basic types are presented. The method of deriving the tensile force calculation is explained for DC as well as for AC electromagnets. There is a detailed description of the design process of a core DC electromagnet, which is then simulated in the FEMM program, and a 3D model with technical documentation is created in the Inventor program. The part also deals with measurement on electromagnets. More precisely, it is a measurement of static and dynamic tensile characteristics, measurement of electromagnets temperature rise. In the next part, transient phenomena and their measurements are explained, namely inrush current and switching overvoltage.
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Assessment of the design of a small photovoltaic power plant for a family house and elaboration of its revision process
Kovaľ, Nikodém ; Šimek, David (referee) ; Veselka, František (advisor)
The bachelor's thesis deals with the assessment of a domestic photovoltaic power plant for a family house and the processing of its revision. At the beginning are explained the principle of conversion of solar energy into electrical energy, types of individual photovoltaic cells used in practice, methods of increasing the efficiency of photovoltaic modules, the most common failures of PV modules and methods of their detection. Furthermore, the assessed photovoltaic power plant is presented, its theoretically described components, graphical dependencies showing its production and the possibilities of increasing its production. The practical part of the work deals with the revision of the assessed PV plant and its documentation.
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