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Warming of the disconnector, type KBE, 38 kV, 4000 A
Švábek, Ondřej ; Šimek, David (referee) ; Bušov, Bohuslav (advisor)
The bachelor's thesis is focused on the theory and calculation of the thermal effects of electric current and temperature-rise test of the disconnector KBE 38 kV, 4000 A. Another important part of this thesis is familiarisation with the electrical devices of the company IVEP, a.s. and studying norms related to disconnectors. The procedure for the calculation of warming of a particular disconnector is described within the thesis. The last part of the thesis evaluates the results of calculation and measurement.
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Process model of the switchgear laboratory
Paloš, Radek ; Bušov, Bohuslav (referee) ; Šimek, David (advisor)
This thesis deals with the issue of process optimization. Especially with two selected methods, Lean six sigma and TRIZ. Both of these methods are briefly described, especially we could find in this thesis chapters about history, options of usage, and description of selected tools for realization. The thesis also deals with the comparison between methods, including their advantages and disadvantages. The next part of the thesis is about process mapping of preparation before testing electrical devices in the UVEE department FEEC laboratory, which is part of BUT. Except process map, there is an analysis of each process, evaluation, and future possible optimization.
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Overloading and short circuits of electric wires
Jurman, Jiří ; Valenta, Jiří (referee) ; Šimek, David (advisor)
The bachelor's thesis discusses the requirements that must be met in practice for electrical distribution systems in terms of the construction and securing of electrical distribution systems against the effects of current overload and conductor shorts according to the relevant Czech and European standards. Furthermore, the work marginally focuses on standardized thicknesses and materials used precisely for insulation. From the point of view of residential wiring of Czech residential distributors and distributor's homes, to compare different conditions in terms of requirements for wires connected to electricity meters. Furthermore, the work certainly refers to programs that are used in practice for the design of electrical elements and conductors for specified electrical parameters based on the parameters themselves, such as the consumption of equipment connected to the electrical distribution. In the thesis, we can find some programs used in practice for this purpose, including a description of their functions and a subsequent comparison of these programs and a model design using a program used in practice. Finally, the thesis evaluates the performed measurement of the influence of the released Joule integral determined using the K2S2 value and, in the second part, determined by the limiting class of the circuit breaker.
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Warming disconnector with earthing switch, type QAKZ, 17 kV, 8000 A
Matoušek, Jiří ; Šimek, David (referee) ; Bušov, Bohuslav (advisor)
This Bachelor’s thesis deals with issues related to heating in context of electrical apparatus. This bachelor’s thesis describes products manufactured by IVEP a.s. Especially indoor disconnectors are described in greater detail. Term that are relevant in context of temperature rise test are also describes in this thesis. These terms are taken from Czech technical standards. Mathematical model of temperature rise test is solved in this thesis. Results of mathematical model are then compared to experimental measurement of disconnector warming.
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Short-circuit resistance of the disconnector KBE, 38 kV, 3150 A
Šťastná, Antonie ; Šimek, David (referee) ; Bušov, Bohuslav (advisor)
The bachelor's thesis is focused on the calculations of electrodynamic forces and short-term warming for the disconnector of the company IVEP a.s. within the framework of the issue of short-circuit resistance. The first part contains a theoretical summary of high voltage switching devices, their division and functions. The next part describes the problem of short-circuit currents, and the third part contains an introduction to IVEP devices. In the fourth part, essential information affecting the short-circuit resistance test of the KBE disconnector, 38 kV, 3150 A, is selected and described from the relevant standards related to the topic of the thesis. The main part of the thesis is devoted to calculations of electrodynamic forces affecting on the relevant disconnector and calculation of short-term heating in critical places of the current-carrying path. In the thesis, the achieved results are commented on and possible adjustments are suggested in case of inequality with the standards.
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Electric arc generator and its plasma analysis
Koreň, Michal ; Kloc, Petr (referee) ; Šimek, David (advisor)
The bachelor thesis deals with the design of a plasma generation device and spectroscopic analysis of the electric arc. The thesis contains a theoretical and a practical part. In the first part, the theoretical issues of electric arc and plasma are explained. Their origin, behaviour, effect on the surroundings and key properties. The different types of spectroscopic methods that can be used for measurements are described. In the practical part, a device that generates an electric arc has been designed. Using the selected method, the key properties of the electric arc were determined. The advantages and disadvantages of the particular method used for the analysis are justified. Using the measured values, the materials present in the spectrum were identified and the plasma temperature of the electric arc generated on the copper electrodes at different distances and different times was calculated. Finally, the proposed plasma generator is critically evaluated, its possible improvements and its use for future teaching purposes are discussed
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Short time overload of cables in UPS applications
Toman, Dominik ; Pravda, Luděk (referee) ; Šimek, David (advisor)
This bachelor’s thesis is about dimensioning power cables in electrical instalation which is described in the third chapter. If is used cable with small cross-section, relatively high direct current which is flowing through these cables could cause too high warming. Function of this electrical instalation and comparison of batteries which should be possibly used, are described in the first chapter. Second chapter shows risk of using cable with small cross-section, which could be overheated due to current overloading. Cables are designing in accordance with IEC 60364-5-52, IEC 60364-5-54 and duty cycle. Cross section values calculated according to all methods are very different. Cross section calculated in accordance to IEC 60364-5-54 and duty cycle are smaller then cross-section values calculated in accordance to IEC 60364-5-52. Cable with smaller cross section is cheaper, but it is possible that smaller cross section could cause bigger warming. This thesis also contains thermal model and warming measurement, both methods are for verification that cable with smaller cross-section could be used. Third chapter also contains calculations of voltage drops on all calculated cross-sections. Values from thermal model and warming measurement are different but they are both confirming that the cable with smaller cross section could be used.
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Electrical device motion mechanism analysis
Hollý, Martin ; Ctibor, Jiří (referee) ; Šimek, David (advisor)
This thesis deals with the analysis of the movement mechanism of electrical devices and the comparison of sensors analyzing object movement. In the first part, position, speed and acceleration sensors are described, divided according to the physical principle of their operation. In the second part, the applicability of individual types of sensors for the analysis of moving parts of electrical devices is assessed, based on a comparison of their advantages and disadvantages. In the third part, the achieved results of the analysis using two selected distance sensors on the switching mechanism of the contactor are compared and evaluated. The last part describes the effect of temperature and position on the dynamics of the switching mechanism.
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Temporally and spatially resolved diagnostics of an electric arc
Holcner, Oldřich ; Šimek, David (referee) ; Kloc, Petr (advisor)
This batchelor thesis "Temporally and spatially resolved diagnostics of an electric arc" deals with the investigation of plasma temperature in an arc formed by evaporation of copper wire. It is an optical method based on determination of temperature from intensity of spectral lines. In this batchelor thesis we explain how spectral lines are formed and how to determine the temperature. In the practical part we process discharge and show the time evolution of temperature at the measured points.
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DC arc extinguishing in low voltage switching devices for critical currents
Fencl, Martin ; Šimek, David (referee) ; Píška, Jakub (advisor)
This bachelor’s thesis deals with DC arc extinguishing for critical currents. The first, theoretical part describes and defines an arc, a DC arc and methods of its extinguishing. The second, theoretical part concerns spectral analysis – specifically, the emission method. Methods of research of extinguishing critical currents are also presented. The practical part consists of two measurements. The first measurement consists of spectrum measuring in time, in conjunction with voltage and current measurements. In the second measurement, the goal was to measure the dependence of arc burning time on voltage and current. The thesis concludes with summary of the results of each individual measurement and their presentation in the wider context.
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