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Testing of arc protection AFDD during normal and fault conditions
Křepela, František ; Dostál, Lukáš (referee) ; Kaser, Jakub (advisor)
The bachelor´s thesis deals with AFDD, a device that protects the low voltage electrical installations against fire caused by a serial or parallel arc fault. Although MCB and RCD can mostly disconnect the circuit when the parallel arc appears, only AFDD can detect the series arc fault. AFDD can be used only as additional protection. The theoretical part of this thesis describes the creation of electric arc, causes of house fires, and explains the principle of the Arc Fault Detection Device. The purpose of the practical part is to create real malfunctions that cause a series arc in the circuit and to test the function of AFDD. The next purpose is to repair the arc generator and to verify the function of AFDD using different materials of electrodes.
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Simplified model of a axial cooled arc
Kasal, Ondřej ; Šenk, Josef (referee) ; Lázničková, Ilona (advisor)
Using of computer technology brings advantages of quick and well-arrange data. Computer technology offers change of transferring information the same way as that often using. Capacity and execution of computer technology is depending on kind and size of elaborated information. It is necessary to use to computer technology in application working with big data range and in application which needs many steps to finish calculation it means when we are using iterative methods. It is computer technology which creates main part of simulation, computation and visualization methods which are using in technical application. Plasma is using in many way of industry from technical manufacturing of materials to application in power electronics. Attention is paid to plasma. To description to fourth state of substance and for description to processes in plasma are used mathematic and physic equations. To solve to equations is hard and we need many steps to cover it. It is necessary to use computer technology to work up different method performs to describe electric arc.
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Investigation of the durability of low voltage switching apparatuses construction parts
Dalecký, Jan ; Dostál, Lukáš (referee) ; Šimek, David (advisor)
This thesis deals with study of durability of low voltage switching devices components. It describes components of circuit breaker and low voltage contactor and contains function models of these devices in various states. Based on model analysis, components that can get worn, damaged or destroyed were selected. Further practical experiments on two samples of circuit breakers from different manufacturers were executed to verify their technical parameters and parts durability. Failure of some components can cause switching device to malfunction.
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Thermodynamic Conditions in Quenching Chamber of Low Voltage Circuit Breaker
Urban, Ferdinand ; Hüttner,, Ľudovít (referee) ; Kapička, Vratislav (referee) ; Aubrecht, Vladimír (advisor)
Práce se zabývá studiem procesů probíhajících při zhášení silnoproudého oblouku ve zhášecí komoře jističe. Je zaměřena na výpočet dynamiky tekutin a teplotního pole v okolí elektrického oblouku. V práci je dále popsán vliv vzdálenosti plechů v komoře a vliv tvarů plechů z hlediska aerodynamických podmínek uvnitř komory. Dalším cílem dosaženým touto prací je poskytnutí informací o vlivu polohy elektrického oblouku na termodynamické vlastnosti uvnitř komory. Toto je důležité, zejména pokud je oblouk do komory vtahován jinými silami, např. elektromagnetickými a během tohoto vtahovacího procesu mění svůj tvar i polohu. Za účelem co nejjednoduššího, ale zároveň co nejefektivnějšího řešení úkolu, byl vyvinut software určen speciálně pro výpočet dynamiky tekutin numerickou metodou konečných objemů (FVM). Tato metoda je, v porovnání s rozšířenější metodou konečných prvků (FEM), vhodnější pro výpočet dynamiky tekutin (CFD) zejména proto, že režie na výpočet jedné iterace jsou menší v porovnání s ostatními numerickými metodami. Další výhodou tohoto softwarového řešení je jeho modularita a rozšiřitelnost. Cely koncept softwaru je postaven na tzv. zásuvných modulech. Díky tomuto řešení můžeme využít výpočtové jádro pro další numerické analýzy, např. strukturální, elektromagnetickou apod. Jediná potřeba pro úspěšné používání těchto analýz je napsáni solveru pro konečné prvky (FEM). Jelikož je software koncipován jako multi–thread aplikace, využívá výkon současných vícejádrových procesorů naplno. Tato vlastnost se ještě více projeví, pokud se výpočet přesune z CPU na GPU. Jelikož současné grafické karty vyšších tříd mají několik desítek až stovek výpočetních jader a pracují s mnohem rychlejšími pamětmi, než CPU, je výpočetní výkon několikanásobně vyšší.
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Usage of high-speed camera in the area of switching arc
Samohejl, Matěj ; Bušov, Bohuslav (referee) ; Valenta, Jiří (advisor)
This bachelor´s thesis is focused on optimizing recording of electrical switching arc in magnetic switches by high-speed camera. Measurements were performed on the circuit breaker 10B without removed side case, which was subsequently cowled by neutral density filter. The voltage and current of the circuit breaker contacts were acquired by measuring system of the Laboratory of switching arc diagnostics. The energy source was motor-generator with a nominal power 16 MVA and test bench consisting of a capacitors and inductors, which have been tuned to the resonance frequency of 50 Hz. Evaluation of the measurements was taken with regard to the brightness distribution levels of the record. Results showed that the mean brightness value varies on the square of the current passing through. For proper localization of the arc, it is necessary to appropriately set the camera exposure. The main problem usually is to darken the scene enough. It was found that it is necessary to take into account that brightness level change depends nonlinear on the exposure offset. The thesis gives a proposal to determine the exposure shift of the record. The possibility of usage high-speed camera to determine the temperature distribution in the arc using the brightness equiintensities was also designed. There are mentioned suggestions how to improve recording of the arc in circuit breakers, especially in the arrangement of the optical parts.
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Theoretical modes of electric arc
Vondrák, Michal ; Šenk, Josef (referee) ; Lázničková, Ilona (advisor)
This thesis deals with theoretical models of the electric arc. Plasma arc and plasma torch are explained. Basic approaches of electric arc modeling are described. The indirect method for the determination of the mean temperature and velocity at the exit of plazma jet plasmatron are discussed. Finally the simplified model with axially-cooled electric arc is described.
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Usage of CAD Systems in Area of Electrical apparatuses
Bojanovský, Lukáš ; Kuchyňková, Hana (referee) ; Valenta, Jiří (advisor)
This thesis presents current possibilities of parametric modelling. In the first section the new features of Autodesk Inventor Series 10 and process of designing model of arc chute cut of circuit-braker BD250 are described. A next section of the thesis describes funcionality of double contact element during switching off, creation and disappearance of electric arc. The principle of electric arc exctincion using magnetic exhaustion into arc chute with the participation of dynamic forces. The data format IGES was used for animation creation and also there is a short description of the history and origin of the format. The position animation in Autodesk Iventor 10 was used for designing animation.
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Usage of LabView in the field of switchgears.
Karpeta, Petr ; Huzlík, Rostislav (referee) ; Valenta, Jiří (advisor)
My aim in Bachelor`s project is familiarization the problems of development environment and LabVIEW measurement card DAQCard-6036E. The implementation of this program in industry, the map application in the field of measuring performance, data collection and automation of electric appliances. Another important point is the basic description of the controls palette of instruments and creating a new program for virtual instrumentation and simulation. Because using a virtual programming language from National Instrument on measured dynamic characteristics of the electrical arc, closer to students and other readers the theory arcs of alternating electric current. Describe the emergence, speeches and behavior of electric arc in atmospheric pressure and normal temperature laboratory room. Provide basic knowledge of the influences acting on burning electric arc and how these effects distort the ideal dynamic characteristics. A proposal for measuring the dynamic characteristics of electric arc in the LabVIEW environment. To measure several volt-ampere characteristics with card DAQCard- 6036E and also been measured in these courses in the current and voltage measurement circuits. Measurement is performed on the product with two carbon electrodes in the vertical arrangement. The result will be a measured dynamic voltampere characteristics with measured data in the form of tables and graphs.
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The arc extinction in electrical apparatuses
Karásek, Ladislav ; Valenta, Jiří (referee) ; Bušov, Bohuslav (advisor)
My bachelor’s thesis is focused on theoretical analysis of the issues of switching arc in electrical devices, introducing successful quenching principles in present devices and the practical part of thesis is focused on innovation of lab exercises „Static V-A characteristics of DC (direct-current) arc and dynamical V-A characteristic of AC (alternating current) arc“, which is part of the course Electrical Devices. Part of the bachelor´s thesis is practical measuring of DC and AC arc, construction of static and dynamic characteristics and its subsequent reviews. The last part of my bachelor´s thesis is focused on innovation of this lab exercis
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Influence of welding direction on depth of penetration for MAG method
Šmak, Radim ; Mrňa, Libor (referee) ; Kubíček, Jaroslav (advisor)
This bachelor thesis deals about Influence of welding direction on depth of penetration in S 235 JR steel for MAG welding. First theoretical part of the thesis was devoted to a description and technology of the chosen method. In the second practical patr of the thesis was designed optimal welding parameters and conditions of welding. Based on them was performed an experiment. From the experiment was detected the depth penetration, heat affected zone and structure of the metal.
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