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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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USING MODERN NUMERIC METHODS IN DESIGN OF LOW VOLTAGE CIRCUIT BREAKERS
Dostál, Lukáš ; Hüttner, Ľudovít (referee) ; Petráček, Miloš (referee) ; Aubrecht, Vladimír (advisor)
The theses is focused on efficient use of numerical methods in development of low-voltage switching devices, namely to create a physically correct and reliable numerical model of the temperature field to find an application in the design of the current path of a device for various operating conditions. The creation of this numerical model requires not only correct inclusion of all modes of heat transfer - conduction, convection and radiation, but also correct solution of problematic transient resistance - both electrical and thermal in electrical contacts at different stages of usage. Therefore an essential part of the theses forms a thorough experimental analysis of the necessary material properties and dependencies which forms input data for the numerical model that is based on the finite volume method. The last part of the theses deals with debugging and verification of numerical model to correspond with experimentally obtained data. The result of the theses is the numerical model which is able to solve correctly both steady and various transient states of swiching devices.
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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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USING MODERN NUMERIC METHODS IN DESIGN OF LOW VOLTAGE CIRCUIT BREAKERS
Dostál, Lukáš ; Hüttner, Ľudovít (referee) ; Petráček, Miloš (referee) ; Aubrecht, Vladimír (advisor)
The theses is focused on efficient use of numerical methods in development of low-voltage switching devices, namely to create a physically correct and reliable numerical model of the temperature field to find an application in the design of the current path of a device for various operating conditions. The creation of this numerical model requires not only correct inclusion of all modes of heat transfer - conduction, convection and radiation, but also correct solution of problematic transient resistance - both electrical and thermal in electrical contacts at different stages of usage. Therefore an essential part of the theses forms a thorough experimental analysis of the necessary material properties and dependencies which forms input data for the numerical model that is based on the finite volume method. The last part of the theses deals with debugging and verification of numerical model to correspond with experimentally obtained data. The result of the theses is the numerical model which is able to solve correctly both steady and various transient states of swiching devices.
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