National Repository of Grey Literature 76 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Measurement of mechanical and electrical quantities of bimetals
Kocian, Štěpán ; Bušov, Bohuslav (referee) ; Valenta, Jiří (advisor)
This bachelor thesis focuses on bimetals. In the theoretical part is described the principle of operation of bimetals, then important parameters of bimetal, including mathematical equations. Furthermore, methods of heating bimetals are mentioned and mathematically described. The last part in theory concentrates on the standards related to the use of bimetals as circuit breakers and the corresponding agreed breaking currents. The practical part deals with measurements on bimetal. This is measurement of free deflection and the force generated by the bimetal depending on the temperature change. From the measured data, the characteristics and the dependences of the properties for bimetal were processed. The last chapter was devoted to the creation of laboratory work.
Electrodynamic forces in low voltage switchgear assembly
Moravec, Štěpán ; Bušov, Bohuslav (referee) ; Valenta, Jiří (advisor)
This bachelor thesis is focusd on issues of forces which are consecquences of an electrical current in an electric low-voltage switchboards. These forces are an effect of the magnetic fields arised from the electric current flowing in a circuit. We have to design electric switchboards which are in the process of use with emhasis on their safety, because the arisen forces are very high especially in a short-circuit. Each of new construction of an electric switchboard has to pass the type test in a testing laboratory for garanting their safety in operation. This thesis also examines the simulation on 3D model of an electric switch board by OEZ.
Assessment of the design of a small photovoltaic power plant for a family house and elaboration of its revision process
Vozárik, Michal ; Valenta, Jiří (referee) ; Veselka, František (advisor)
This bachelor thesis includes the issue of photovoltaics with a specific photovoltaic power plant, supplemented by basic measurements during inspection activities. In the first part, the author deals theoretically with solar radiation and the photovoltaic field. In the second part of the work, the author deals with the issue of revision activities. Within the work, a specific design of a small photovoltaic power plant on the roof of a family house is assessed. Various sizing software were used to analyze and assess the object. Part of the work is also the procedure of verifying the parameters of the PV plant and the inspection report of the revised electrical equipment.
Investigation of correlation between arc voltage and arc movement
Szotkowski, Šimon ; Valenta, Jiří (referee) ; Kloc, Petr (advisor)
The electric arc burns in an ionized gas and is divided into AC and DC arc according to the power supply. The electric arc is conductive, so to turn off the electric circuit, the arc must be extinguished as soon as possible. Arc breakers are used to extinguish the arc. Arc breaker must be designed to withstand the increased pressures and temperatures caused by the arc. The purpose of the bachelor's thesis was to design and construct a arc breaker with the possibility of monitoring the movement of the arc with a high-speed camera. From the measured data, the dependence between the arc voltage and the movement of the arc root was determined by correlation analysis. Correlation analysis is used to calculate the possible existence of a dependence between two quantities with the correlation coefficient and testing.
Mathematical model of RCCB sensitive to pulsating direct currents
Kaser, Jakub ; Dostál, Lukáš (referee) ; Valenta, Jiří (advisor)
This Thesis deals with problematics of residual current circuit breaker and its eventual operation malfunction due to DC components. There are magnetic phenomena described in details which occur inside of the apparatus. Consequently, there is proposed a mathematical model of the circuit breaker in Simulink program. The comparison of B-H curves of transformer core is composed and achieved results are incorporated into the proposed model in order to verify a correct operation of the circuit breaker and its reaction to different conditions. The verification of the symmetry of the magnetic field in residual current circuit breaker in Ansys Maxwell program is also a part of the study.
Switching arc diagnostics in DC contactor
Píška, Jakub ; Kloc, Petr (referee) ; Valenta, Jiří (advisor)
Cílem této diplomové práce bylo provést diagnostiku vysokonapěťového stejnosměrného stykače se zaměřením na zpětnou komutaci a lepení oblouku, navrhnout a ověřit úpravy, které odstraní tyto negativní jevy. Měření obloukového napětí, tlaku a pomocí rychlokamery byly použity při diagnostice těchto jevů. Změny na arcrunnerech a jhu magnetického obvodu byly využity při jejich odstraňování. Úpravy na arcrunneru zmenšily skokové nárusty délky oblouku a úpravy na jhu navýšily sílu na oblouk mezi rozevírajícími se kontakty. Navrhnuté změny na stykači snížily časovou ztrátu v důsledku zpětné komutace, a tak zkrátily čas přenosu oblouku.
Analysis of electrodynamic forces in electrcal apparatus
Dobrovolný, Jan ; Valenta, Jiří (referee) ; Šimek, David (advisor)
The master thesis deals with the phenomena called electro-dynamic force in the electrical apparatus. Nowadays, there are high requirements for electrical devices. The devices and especially their contacts are subject to high demands on reliability, reliability and mechanical durability. The electro-dynamic forces caused by the passage of electric current mechanically deform the current path. The design of the electrical apparatus must take these forces into account. Equations for electro-dynamic forces calculation are presented. In master thesis, individual parts of the current path are derived and described. Various configurations and designs of the current path are solved. The thesis also deals with the issue of forces in electrical contacts. Individual theoretical equations are then applied to a particular disconnector QAK, made by company IVEP, a.s. Parts of the disconnector were redrawn into 3D program SolidWorks. The model was analysed in program ANSYS Maxwell. The thesis compares the achieved results of analytical equations and numerical simulations.
Development of DC arc quenching chamber
Černohorský, Petr ; Valenta, Jiří (referee) ; Šimek, David (advisor)
Seminar thesis focuses on the issues about quenching the electric direct arc by the quanching system. Teoretical part deals with action about quanching the direct arc and with another actions which happens in direc discharge. There is described proposal and construction of the insulating quenching system. Than chamber was testing in high voltage laboratory and the results from testing was evaluated.
A Sample ARC Detector Panel
Pala, Lukáš ; Valenta, Jiří (referee) ; Kadlec, Radim (advisor)
In the introduction an electric arcs creation in low voltage networks is discussed, followed by evaluation of verification measurements with AFDD. A serial arc generator is designed in accordance with easy manipulation and low maintenance requirements. Technological solution for safe fault simulation is described similarly as particular function sections of demonstration panel. Schematic diagrams of power and electronic circuits are attached.
Residual current device behavior under switching of non-sinusoidal residual currents
Horký, Jakub ; Dostál, Lukáš (referee) ; Valenta, Jiří (advisor)
This bachelor deals with behaviour of a residual-current device during disconnection non-sinusoidal residual current. In the first, theoretical part, basic characteristics and properties of electrical devices are described. Attention is devoted to residual-current device, its structural part, parameters and types. Afterwards, there are described normative requirements of the residual-current device type A in the course of tests. The second part is a practical part. The residual-current device is subjected to residual currents with direct current components (according to the standard), thereby it is checked if it works correctly, it means, if the device is capable of being cut off, At the end of the bachelor, where is a sample laboratory task that demonstrates a check the behavior of the residual-current device at switching off the non-sinusoidal current.

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See also: similar author names
6 Valenta, Jakub
13 Valenta, Jan
14 Valenta, Jaroslav
3 Valenta, Josef
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