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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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Experimental Measurements Of High Temperature
Objects In Contact With An Electric Arc
Šimek, David
The paper is focused on the measurements of high temperatures related to electric low voltage apparatuses switching off process. An optical emission spectroscopy was used for these measurements, because the optical emission spectroscopy is one of best methods for obtaining a temperature of high temperature objects. Experimental measurement of radiation spectra of electrodes among which an arc was burning is presented. Electrodes was made of carbon with stabilisation core with potassium and sodium admixture. Radiation spectrum of electrodes was close to the black body radiation spectrum. The problems connected with the measurements are discussed. The main part of the paper deals with a calculation of the electrode temperature using Planck function.
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Design of earthing switch for diconnecter of generator
Petrič, Peter ; Šimek, David (referee) ; Bušov, Bohuslav (advisor)
This master thesis is focused on the design of earthing switch for the indoor three pole generator disconnector from IVEP, a.s. The main task of the theoretical part of the master thesis was mechanical and electrical calculations on the contact system and the design of two variants of earthing switch construction. It has been proposed two variants of earthing switch construction. The first variant included three earthing knives for each pole of earthing switch and the other variant included two earthing knives for each pole. The aim of the practical part of this diploma thesis was to create a model of the earthing switch for generator disconnector, to simulate the heating of the contact system by passing the short-circuit current and to prepare the production documentation. For modeling, calculations and simulations were used Autodesk Inventor 2018, Matlab and Ansys Workbench.
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Experimental Analysis of Low Voltage Arc Between Carbon Electrodes with Unknown Cores
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 unknown cores is presented. Measured radiation spectrum has a lot of suitable atomic spectra lines for comparison purposes. The problems connected with the measurements are discussed. The main part of the paper deals with a prediction of composition of the measured arc plasma. Atomic lines database of National Institute of Standards and Technology was used as a spectral data source for the calculations.
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Contact erosion of switching devices
Píška, Jakub ; Šimek, David (referee) ; Valenta, Jiří (advisor)
This bachelor thesis deals with the erosion of contacts, as one of the negative phenomena affecting contacts of switchgears. In its first part, it briefly summarizes the other negative influences that must be considered when designing switching devices. In the following part, the physical mechanism of erosion and the primary criterion of assessment - weight loss are approached. The last and main part of the work deals with design of the contact system for comparing this loss for for frequently used materials and testing on a real switchgear. After the tests, the results were analyzed primarily from the perspective of ignition angles, the polarities of the current pulse and the current flowing through the arc. Taking into account the influence of the material composition, the size of the contacts and the presence of the arc-runner.
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Electrodynamic forces in electrical apparatuses
Dobrovolný, Jan ; Bušov, Bohuslav (referee) ; Šimek, David (advisor)
The bachelor's thesis deals with phenomena caused by electrical current passing through electrical apparatuses current path. The main focus is on electrodynamic forces. These forces are created by the interaction of magnetic fields and significantly takes effect in case of short circuits because they rise with square of current. Electrodynamic forces are problematic especially in contacts, where it causes a repulsive force working against the contact force. A proposal of electrical apparatus must take into account these forces and must be sufficiently dimensioned. Selected apparatus - disconnector, is redrawn into 3D program SolidWorks. Electrodynamic forces on individual parts of current carrying path were calculated for short circuit current. Total balance of forces is created. The disconnector has been tested for a withstand current to verify an endurance against electrodynamic forces.
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Design of earthing switch for diconnecter of generator
Petrič, Peter ; Šimek, David (referee) ; Bušov, Bohuslav (advisor)
This master thesis is focused on the design of earthing switch for the indoor three pole generator disconnector from IVEP, a.s. The main task of the theoretical part of the master thesis was mechanical and electrical calculations on the contact system and the design of two variants of earthing switch construction. It has been proposed two variants of earthing switch construction. The first variant included three earthing knives for each pole of earthing switch and the other variant included two earthing knives for each pole. The aim of the practical part of this diploma thesis was to create a model of the earthing switch for generator disconnector, to simulate the heating of the contact system by passing the short-circuit current and to prepare the production documentation. For modeling, calculations and simulations were used Autodesk Inventor 2018, Matlab and Ansys Workbench.
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Analysis of effect of the switching system of low voltage breaker on the thermal tripping unit
Liščák, Jiří ; Šimek, David (referee) ; Dostál, Lukáš (advisor)
Main aims of this master’s thesis are executing measurements and simulations on low voltage circuit breaker and analyzing effect of the switching mechanism on the thermal tripping unit. There are two programs used for simulations in this thesis ANSYS and SolidWorks Flow Simulation. As another part of the thesis were done two types of tests. First was electrical durability test and second one was warming test. In this thesis were measured values of warming on whole current path not only on thermal tripping unit.
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Protection of business competion - agreements interfering with competition
Šimek, David ; Horáček, Vít (advisor) ; Horáček, Tomáš (referee)
The purpose of my thesis is to analyse two issues arising out of the European and Czech competition law provisions prohibiting agreements which restrict competition. First, I shall examine the issue of distinction between prohibited agreements and allowed unilateral conduct. Furthermore, I shall explore the definition of the concerted practice as interpreted by the Court of Justice of the European Union and Czech administrative courts focusing again on the distinction between such practice and unilateral conduct. Second, I shall elaborate on the structure of Article 101 TFEU. As a consequence of the "more economic approach" taken by the Commission and the repeal of the individual exemption system under Article 101(3) TFEU, the distinction between the concept of object offences and the concept of effect offences is slowly disappearing while having detrimental implications for legal certainty. Moreover, the conceptual distinction between considerations of ancillary restraints under Article 101(1) TFEU and consideration of pro-competitive and anti-competitive effects under Article 101(3) TFEU is slowly disappearing as well. The economics take their role in the assessment, and that is also the reason why I chose this topic because I am interested in the overlap between law and economics. My thesis is...
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Electric arc heating
Kahoun, Karel ; Bušov, Bohuslav (referee) ; Šimek, David (advisor)
This bachelor's thesis deals with an arc heating in industrial applications. In this paper, there is described laboratory equipment for the generation of electric arc. Thesis also contains theoretical analysis of heat transfer from the arc to nearby object. The main part of the thesis is devoted to experimental measurement of heat transfer from the arc to the nearby object in relation to the electrical power and the surface finish of the object.
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