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Affecting the function of thermal release of circuit-breakers for different connection systems
Lednický, Ján ; Vetiška, Vojtěch (referee) ; Dostál, Lukáš (advisor)
Right function of securing electrical installations is one of the most important factors preventing people, animals and electrical devices themselves from being electrocuted. Circuit breakers with an overcurrent tripping unit work with bimetal. When the bimetal is warmed up enough, it causes disconnection of circuit. This prevents people and animals from being harmed. To make overcurrent tripping unit work the right way, we have to minimise unnecessary disfunction factors caused by thermal thaw and Joule´s heat. This thesis is aimed at gaining general knowledge of heat transmission and transition of electrical current into heat. There are going to be made temperature-rise curves using all available connection sets to evaluate the impact of each one on the tripping unit. Then, a temperature profile of the circuit breaker will be made using a simulation made using SoildWorks Flow Simulation program. Finally, critical places of the current path will be observed.
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Design of electrical installations in industrial buildings
Cabal, Jan ; Bátora, Branislav (referee) ; Toman, Petr (advisor)
The thesis deals with planning and proportioning of electrical installations within industrial objects. The theoretical part of the thesis looks into electrical installation planning and proportioning for all kinds of buildings. Basic terms related to projecting, project requirements, as well as the requirements on the designer, project documentation composition, and project documentation grades, are descibed. Furthermore, the text covers implementations of protection against electrical injuries, related legislative regulations and requirements, and finishes with the issues of electrical installations proportioning and protection. The practical part of the thesis contains a design of electrical installations for an industrial object involving high power wiring for a mechanical – technological part of the Zaječí water treatment plant. In addition to wiring proportioning and protection, the design involves a technical report, layout drawing and distributor RM1 plan.
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Experimental verification of properties of circuit breaker quenching chamber
Kadrnka, Petr ; Vávra, Zdeněk (referee) ; Valenta, Jiří (advisor)
The circuit breakers are able to switch on and off automatically either the short circuit currents up to the limits of their breaking capacity. While the disconnection of the contacts in the switching devices are generated by the arc then it is needed to put it out quickly. A manner of the arcing in the electrical switching devices is influenced by several different factors. It must be taken into account the dynamics of a plasma, a current flowing in the electrodes, a flowing stream in a plasma and a magnetic field generated by a flowing current. This paper is devoted to describe the manner of the arcing in the arc chamber. The experiments carried out in an experimental way attempt to explain, specify and thoroughly comprehend the movements and the characteristics of the arc in a metal arc and in a metal enclosure circuit breaker.
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Calculation of electrodynamic forces in 1600 A circuit breaker
Musil, Pavel ; Bušov, Bohuslav (referee) ; Valenta, Jiří (advisor)
The thesis is focused on the calculation of electrodynamic forces that counterwork on moving contacts of compact circuit breaker BL1600 from the company OEZ Letohrad. The thesis is divided into separates chapters that build on themselves. In the introduction the reason why we deal with calculation of dynamic forces and structural arrangement of current carrying path is described. In the following chapter there is a theoretical analysis of electrodynamic forces that conterwork on individual parts of circuit breaker´s element. The third part is devoted to structural arrangement of the circuit breaker BL1600. In this part we can find an example of using the circuit broker Modeion in practice. Two next chaptures deal with adjustment of the model of current carrying path which then serves for the calculation of electrodynamic forces. The rest of the thesis is devoted to my own calculations. These calculations are mainly stationary where we try to find the forces that conterwork on the contacts in a steady current and in a point in time. There are also dynamics calculation when we can watch the forces that counterwork on contacts in a certain time interval. The last chapter is devoted to a stationary calculation of forces that counterwork on the electrical arc which arises while turning the short-circuit current off. The obtained results are evaluated in partial conclusions of this thesis.
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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.
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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.
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Eco-analyze of Electric Products
Šebela, Petr ; Ing. Jiří Zpěvák, OEZ s.r.o., Letohrad, Czech Republic (referee) ; Szendiuch, Ivan (advisor)
This work deals with ecological design and appraisal of quality of the electronic devices throughout their life cycle. This area known worldwide as Eco-Design, becomes an integral part of all electro technical productions. This work brings out not only conception of the Eco-Design, but also next related areas with the aim to decrease limitation of negative impact on environment. At the end of the work is compared and summarized the ecological evaluation of the concrete product types.
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Usage of high-speed camera in the area of switching arc
Samohejl, Matěj ; Bušov, Bohuslav (referee) ; Valenta, Jiří (advisor)
This bachelor´s thesis is focused on optimizing recording of electrical switching arc in magnetic switches by high-speed camera. Measurements were performed on the circuit breaker 10B without removed side case, which was subsequently cowled by neutral density filter. The voltage and current of the circuit breaker contacts were acquired by measuring system of the Laboratory of switching arc diagnostics. The energy source was motor-generator with a nominal power 16 MVA and test bench consisting of a capacitors and inductors, which have been tuned to the resonance frequency of 50 Hz. Evaluation of the measurements was taken with regard to the brightness distribution levels of the record. Results showed that the mean brightness value varies on the square of the current passing through. For proper localization of the arc, it is necessary to appropriately set the camera exposure. The main problem usually is to darken the scene enough. It was found that it is necessary to take into account that brightness level change depends nonlinear on the exposure offset. The thesis gives a proposal to determine the exposure shift of the record. The possibility of usage high-speed camera to determine the temperature distribution in the arc using the brightness equiintensities was also designed. There are mentioned suggestions how to improve recording of the arc in circuit breakers, especially in the arrangement of the optical parts.
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Tests of motor operarators for low voltage circuit-breakers
Mlynář, Zdeněk ; Polák, Jiří (referee) ; Valenta, Jiří (advisor)
Nowadays increasing demands for energy, safe use and automation in modern systems. The last two mentioned areas can now be relatively easily done using low voltage circuit breakers, along with accessories. The main element is a motor operator of circuit breaker that can operate fully automatically. But that could be the motor operator together with a circuit breaker is sold, it is necessary to fulfill a number of requirements. This work deals with their summarization, partitioning and sequential treatment of individual tests that are necessary for motor operator or required by customers.
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