|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
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.
|
|
|
Diagnostics of medium voltage and high voltage circuit breakers
Kapalla, Alexej ; Šimek, David (referee) ; Dostál, Lukáš (advisor)
This bachelor work is focused on medium-voltage and high-voltage circuit breakers and their diagnostics. The thesis presents the history of HV circuit breakers and their main division. Subsequently, the relevant standards are listed in the work and diagnostics of the MV circuit breaker VD4 and the HV circuit breaker S1-245 from AEG is performed. In case of the VD4 circuit breaker, a new and used circuit breaker was diagnosed. The measured values are then compared and the impact of usage is shown. The work describes the measurement of main contact resistance, insulation resistance, closing and opening times and vacuum quality.
|
|
|
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.
|
|
|
Designing and testing of low voltage switchgears
Kovář, Zdeněk ; Dostál, Lukáš (referee) ; Šimek, David (advisor)
The thesis is focused on a temperature-rise of a low-voltage switchgear. The first part of the work deals with a technical standard related to the chosen topic, compares software used for designing switchgear in practice and familiarizes with the working environment of the software selected for this work. The main part of the work is dedicated to a measurement and a simulation of the temperature-rise of the low-voltage switchgear. The measurement involved testing of the switchgear with regard to the individual functional units and to the whole switchgear. Subsequently, the simulation of the temperature-rise of the switchgear followed. Software used in this work is SolidWorks Flow Simulation chosen due to a wide range of functions. According to the findings there were proposed adjustments of the switchgear with respect to the technical parameters and the economic aspect in the last part of the thesis.
|
guest ::
