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Measurement of HV equipments by electronic bridge.
Kumičák, Ivan ; Pelikán, Luděk (referee) ; Krbal, Michal (advisor)
The main idea of this thesis is measurements of dielectric materials by using a device Tettex. The thesis is about basic physic properties of dielectric materials. The determination of a dielectric material is considered. The behavior of these materials in electrical fields and reasons, those can have an influence on it, are considered as well. In the text are described measuring methods of chosen parameters of dielectric materials by device Tettex and its functional principles. There are an evaluation of measurements, which were done, and a discussion about achieved results.
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Insulator testing
Dovčík, František ; Krbal, Michal (referee) ; Toman, Petr (advisor)
The thesis “Testing of Insulators” deals with insulators and methods used for their high-voltage testing. The thesis was formed on the basis of the effective regulations regarding testing, primarily ČSN EN 60060-1, in order to create a laboratory study in a high voltage laboratory for students of the field of study Power Electrical Engineering at VUT FEKT. With respect to laboratory facilities, the thesis deals with insulator testing by lightning impulse voltage. The chosen up-and-down method is recommended by relevant technical regulations for insulator testing. The objective of this thesis is to acquaint students with high-voltage testing as well as insulators.
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Heat loss of tap-off units of a busbar trunking system
Koudelka, Jan ; Krbal, Michal (referee) ; Zezula, Michal (referee) ; Lázničková, Ilona (advisor)
The thesis deals with the issue of design of tap-off units of a busbar trunking system in point of view of a heat loss. At first the issue of busbar trunking systems as an alternitive to wires is presented in the thesis. Then there is a deep analysis of a design of a tap-off unit, including the issue of calculating the temperature-rise. For the design, a computer program was created, whose presentation makes up the cardial part of the thesis. Not only its parts are described, but also there is written how to work with it and which datas it uses. At last results of the design of the tap-off unit in the program are compared to the results of the type test of the temperature-rise.
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Optimization of the lifecycle transformer 110/22 kV
Suk, Jiří ; Radil, Lukáš (referee) ; Krbal, Michal (advisor)
The aim of the thesis is to describe the situation in transformation 110/22 kV in distribution area E.ON East. Next to describe the current practice in the replacement of 110/22 kV transformers and mention the possibilities of replacing the machines at the end of their lifecycle with respect to the development of the load of the individual transformer stations in the distribution area. An integral part of the thesis is also the economic evaluation of premature replacement of transformers from two different perspectives. The next point is to look at the current possibilities in the lifecycle lengthening of these devices and to suggest a method for monitoring the state of paper insulation to estimate the remaining lifetime of the transformer. The last point is the evaluation of the transition of a significant customer from a voltage level of 22 kV to a voltage level of 110 kV, including related technical and economic issues.
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LED failures
Doležal, Petr ; Krbal, Michal (referee) ; Pavelka, Tomáš (advisor)
This bachelor thesis is dealing with description of the principle generation light in the LED light sources. In the text we can find principle function of LED, history, possibilities of brightness control, power supply and various types of structures. There are described photometric and electrical parameters. Other part of this thesis is the description of effects leading to failure and malfunction of LED light sources. The practical part of this thesis contains measuring on samples of power LED emitting white light and verification of operational effect leading to the failure of LED light sources.
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The Influence of Temperature to Change Operational Parameters and Lifetime of Powerful LEDs
Zeman, Milan ; Pavelka, Tomáš (referee) ; Krbal, Michal (advisor)
The aim of this bachelor’s thesis is the introduction of changes in operating parameters and lifetime period of LED module. The theoretical part is dedicated to a principle of light, the development and use of LED. The main emphasis is placed on PN junction degradation due to temperature and lifetime period of the LED module. The practical part of this thesis contains measuring of LED diode Cree XLamp XR-E in the course of temperature from 0°C to 90°C in the current range of 0-300% of nominal value. Efficiency of LED operation is highly dependent on PN junction temperature. When powering the LED to approximately 65% of the rated power, the conversion of electric energy to light is the most efficient. It depends on junction temperature because increasing temperature decreases efficiency. A very important factor when designing the lighting system is cooling which helps to dissipate heat from the chip.
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Evaluation of the contribution of daylight in the hybrid lighting system
Pavlík, Denis ; Krbal, Michal (referee) ; Škoda, Jan (advisor)
The aim of the bachelor thesis is to evaluate the current status of the associated lighting system in the corridor of the building Technology university of Brno Faculty of Electrical Engineering and Communication Technic 12. The work provides the research of the lighting technologies. The second part focuses on the simulation of the associated lighting system in the computing programs Relux and Vivaldi. The evaluation of the artificial lighting system is done by hand measuring of the object and simulation of the model of the corridor in Relux. Furthermore, there is also a simulation of the associated lighting system with the contribution of daylight according to CIE for the overcast sky prepared in Relux. The simulation of the dynamic lighting scenes is adapted in Vivaldi in order to meet the criteria of standard ČSN 12464-1 for object “corridor”. The program Vivaldi put together the process of the associated lighting system in time and evaluates its economic aspects, too.
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Voltage tests under wet condition
Vondrák, Michal ; Štěpánek, Jaroslav (referee) ; Krbal, Michal (advisor)
The main objective of presented thesis is to design a shower system in order to extend voltage tests by voltage wet testing. The introduction focuses on important aspects related to voltage wet testing. Such aspects originates mainly from Czech but also foreign standards. Following part of the thesis deals with specific wet testing design proposals, which fulfil the standards requirements. The final part of presented thesis is focused on partial experiments. Namely the analysis of rain water properties, behavior of rain drops exiting the nozzle with varying flow and nozzle angle, wet test on insulator in dry and wet conditions.
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