National Repository of Grey Literature 33 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Thermal spray by electric arc
Eliáš, Vojtěch ; Sigmund, Marián (referee) ; Kubíček, Jaroslav (advisor)
This thesis deals with the issue of thermal spraying by means of an electric arc. First of all, a theoretical part is processed using a literary study dealing with corrosion and thermal spraying technology. The experimental part contains a description of the technological procedure and evaluation of four thermally sprayed samples. Zinacor 850, consisting of 85% zinc and 15% aluminum, was used as a coating. The evaluation involves measurements of thickness, adhesion and roughness as well as the macro-structural analysis of the coating. Two samples showed unusually low adhesion, and all samples also had a large fluctuation of the measured thicknesses. This was also confirmed by the macro-structural analysis, which showed that the sample with low adhesion also had high porosity. These defects may have multiple causes, but the recommendation for further practice is to reduce the spraying distance from the base material.
Investigation of correlation between arc voltage and arc movement
Szotkowski, Šimon ; Valenta, Jiří (referee) ; Kloc, Petr (advisor)
The electric arc burns in an ionized gas and is divided into AC and DC arc according to the power supply. The electric arc is conductive, so to turn off the electric circuit, the arc must be extinguished as soon as possible. Arc breakers are used to extinguish the arc. Arc breaker must be designed to withstand the increased pressures and temperatures caused by the arc. The purpose of the bachelor's thesis was to design and construct a arc breaker with the possibility of monitoring the movement of the arc with a high-speed camera. From the measured data, the dependence between the arc voltage and the movement of the arc root was determined by correlation analysis. Correlation analysis is used to calculate the possible existence of a dependence between two quantities with the correlation coefficient and testing.
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.
A Sample ARC Detector Panel
Pala, Lukáš ; Valenta, Jiří (referee) ; Kadlec, Radim (advisor)
In the introduction an electric arcs creation in low voltage networks is discussed, followed by evaluation of verification measurements with AFDD. A serial arc generator is designed in accordance with easy manipulation and low maintenance requirements. Technological solution for safe fault simulation is described similarly as particular function sections of demonstration panel. Schematic diagrams of power and electronic circuits are attached.
Spectroscopic analysis of an electric arc
Hartman, Tadeáš ; Kloc, Petr (referee) ; Šimek, David (advisor)
The bachelor thesis deals with spectroscopic diagnostics of electric arcs. The first part explains the creation and properties of electric discharges, especially electric arcs. Methods for composition and temperature analysis of electric arcs are also given there. The next part deals with practical use of these methods for identification of elements contained in electrodes between which an arc discharge was happening, measurement of the arc temperature and also measurement of the temperature of the electrodes. In the last part, these methods are also used for the analysis of time progression of composition and temperature of an electric arc created on a contactor's contacts with the resistive load.
Analysis Of Contact Disconnection In A Low Voltage Circuit Breaker
Mačák, Martin
This work deals with a simulation of plasma phenomenon and with a simulation of an arc ingnition between contacts in a low voltage circuit breaker. Simulations were made in Ansys Fluent with the usage of MHD (Magnetohydrodynamic) add-on module and additional UDFs (User Defined Functions). Mathematical model presented in this work connects electric and magnetic field, which is not possible in Ansys Fluent by default.
Switching arc plasma diagnostics by usage of two high-speed cameras
Buchta, Martin ; Dostál, Lukáš (referee) ; Valenta, Jiří (advisor)
This bachelor thesis deals with an electrical arc formation and its properties. The thesis also describes some of the electrical devices and principles, which are used for arc extinction. It is mainly focused on design, construction and testing of model of the LV quenching system, which allows high speed cameras to record arc movement. Recorded images are then used to create three-dimensional reconstruction of the electric arc with help of created program 3DMaker. The final reconstruction is the output of this work.
Electric fault arc detection in LV network
Dubský, Martin ; Fencl, Jiří (referee) ; Dostál, Lukáš (advisor)
This thesis deals with arc detection using AFDD. Here is explained the general theory of electric arc. It also describes the principle of operation of the AFDD device, a specific type of instrument from OEZ s.r.o. and describe the test procedure for this instrument according to the technical standard. In the practical part, selected tests are performed and verified the function of the AFDD device in the event of a disturbance electric arc in the circuit.
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.
Welding of steel C45
Hála, Kamil ; Sigmund, Marián (referee) ; Kubíček, Jaroslav (advisor)
The aim of this bachelor‘s thesis is to propose a suitable welding parameters for a small part of steel C45. This steel contains a high percentage of carbon and therefore is difficult to weld. Gas shielded arc welding techniques were considered to be used, and from such techniques, the TIG method seems to be the most advantageous one. For this technique were suggested three groups of parameters and the most suitable one was chosen to be used for the production. The option chosen is of a welding power I=40 A and with preheating 200 °C. The component is made in the single-part production in SAAB Czech s.r.o.

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