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Calculation of electrodynamic forces in 630 A circuit breaker
Staněk, Pavel ; Bušov, Bohuslav (referee) ; Valenta, Jiří (advisor)
The aim of this thesis is to simulate the action of electrodynamic forces on current carrying path and a movable contact of the circuit breaker OEZ Modeion BH 630NE. For the calculation there is used the simulation program Ansys Maxwell. The first part is devoted to theoretical analysis of electromagnetic forces on a conductor in a magnetic field. Further I discuss the constructional design of the circuit breaker itself, especially the current path and the contact mechanism. In the next part there is (with using program Autodesk Inventor) created a simplified 3D model of the current path including an arc chamber. With program Ansys Maxwell then there is performed simulation of the acting of forces in each mode. This is magnetostatic and transient analysis for symmetrical and asymmetrical flow of the fault current. In conclusion the results obtained are evaluated and processed in the tabular way.
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Evaluation of nonstandard operation possibilities of power sources in MV network
Čáslava, Jiří ; Opat, Jaroslav (referee) ; Topolánek, David (advisor)
This Master's thesis deals with solution of nonstandard operation connection of E.ON's 22kV distribution network in given area, considering the possibilities of operating dispersed electric power sources currently available, as well as possible power sources connected to the distribution network in the future and its potential operation limitation. A part of this paper is a description of calculation methods used for network evaluation in steady state, with emphasis on linear calculations used by E-Vlivy program, in which the operational possibilities are simulated. Therefore, a description of this program is also included. Suggested operation possibilities correspond with E.ON's valid distribution network operation rules. The outcome of this paper will serve to E.ON's 22kV network's controllers as materials for network operating in nonstandard operation states.
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Determination of the Temperature Field in a Real Circuit Breaker
Pěček, Dominik ; Aubrecht, Vladimír (referee) ; Kloc, Petr (advisor)
This master thesis deals with determination of temperature field in a real circuit breaker. This issue is solved by analysis of measured emission spectra at selected points of the circuit breaker. Spectral line ratios and Boltzmann plot are used for calculation of temperature. These methods are based on elemental analysis of plasma. The main result is finding significant changing of chemical composition of plasma beyond determination of temperature field.
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Contact erosion of switching devices
Píška, Jakub ; Šimek, David (referee) ; Valenta, Jiří (advisor)
This bachelor thesis deals with the erosion of contacts, as one of the negative phenomena affecting contacts of switchgears. In its first part, it briefly summarizes the other negative influences that must be considered when designing switching devices. In the following part, the physical mechanism of erosion and the primary criterion of assessment - weight loss are approached. The last and main part of the work deals with design of the contact system for comparing this loss for for frequently used materials and testing on a real switchgear. After the tests, the results were analyzed primarily from the perspective of ignition angles, the polarities of the current pulse and the current flowing through the arc. Taking into account the influence of the material composition, the size of the contacts and the presence of the arc-runner.
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Diagnostics of air circuit breaker for low voltage
Bartoš, Jan ; Pavelka, Samuel (referee) ; Bušov, Bohuslav (advisor)
This bachelor work is focused on low-voltage circuit breakers. It also includes the history of the low voltage circuit breakers. Subsequently, the label values of the Siemens air circuit breaker are described and the comparison of this circuit breaker with competitors' products is shown. Basic principes of diagnostics is explained in this bachelor work. Work is focused on examination of the standardized type tests such as temperature rise test, tripping limits and characteristics test, dielectric properties test.
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USING MODERN NUMERIC METHODS IN DESIGN OF LOW VOLTAGE CIRCUIT BREAKERS
Dostál, Lukáš ; Hüttner, Ľudovít (referee) ; Petráček, Miloš (referee) ; Aubrecht, Vladimír (advisor)
The theses is focused on efficient use of numerical methods in development of low-voltage switching devices, namely to create a physically correct and reliable numerical model of the temperature field to find an application in the design of the current path of a device for various operating conditions. The creation of this numerical model requires not only correct inclusion of all modes of heat transfer - conduction, convection and radiation, but also correct solution of problematic transient resistance - both electrical and thermal in electrical contacts at different stages of usage. Therefore an essential part of the theses forms a thorough experimental analysis of the necessary material properties and dependencies which forms input data for the numerical model that is based on the finite volume method. The last part of the theses deals with debugging and verification of numerical model to correspond with experimentally obtained data. The result of the theses is the numerical model which is able to solve correctly both steady and various transient states of swiching devices.
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The measurement of bimetal for a switching device
Bartek, Zbyněk ; Bušov, Bohuslav (referee) ; Kaser, Jakub (advisor)
This bachelor thesis deals with the thermal trigger of bimetallic-based safety devices. The theoretical part describes the principle of the function of bimetal, materials and production of bimetal, and important parametres of bimetal including mathematical description. Furthermore the advantages and disadvantages of specific bimetals, types of bimetals and their practical use, and standards dealing with circuit breakers are also described. The last theoretical part of the work describe basic calculations for the design of bimetal. In the practical part were measured the free deflection of the bimetals, the results obtained were processed into graphic dependencies and compared with theoretical values.
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Evaluation of a switching device behaviour during short-circuit current
Fendrych, Martin ; Dostál, Lukáš (referee) ; Valenta, Jiří (advisor)
At work, I focused on the principle of electric arc extinction in low voltage devices. I particularly focused on the issue of magnetic switches. Next, I processed by the theory site issue of contact system in magnetic switches. In the practical part of my work, I was testing modular low voltage circuit breaker type of 2B and 10B. Testing was carried out in the laboratory of switchgear. I observed the movement of the contact and electric arc, which was burned between them and conductor wall. Observation was recorded by using a high-speed camera and an oscilloscope. Of acquired waveforms, I evaluated the dynamics of contacts, electric arc length and the value of the arc voltage for different moments.
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Electrical installation in family home
Pokorný, Marek ; Bátora, Branislav (referee) ; Macháček, Jan (advisor)
The goal of this bachelor paper with the topic " Electrical installation in family home" is to describe laws and public notices that relate to an electrical setting; relevant norms and conditions for a connection to a distribution network (low tension service lines); ways of connections and its location. Furthermore, this paper describes operational conditions, external effects, dimensioning, cabel lodgements and protection (its ways, principles, security and conductor). In a separate chapter low tensinon switch-boards distribution and its instrumentation is covered. Another sphere of this bachelor paper is the field of illumination and lamps. The following chapter deals with sorts of electrical setting (classic, intelligent), low-tension electrical setting (PC distributions), fire and safty electrical setting and audit report elaboration. A practical sample of a electrical installation in family home is shown at the end of this paper
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Software for evaluation of data from CVVOZE laboratory
Petráček, Dominik ; Šimek, David (referee) ; Pikula, Stanislav (advisor)
The diploma thesis is focused on the innovation of partially user-unsuitable software which is used in the CVVOZE short-circuit laboratory for the evaluation of testing of switching and protection devices. The introductory part of the work presents a technical laboratory, which is used for research and development in the field of electrical devices with possibility of testing of short circuits and over-currents. At the first part of thesis, there is made a description of the technical laboratory. The following past is a chapter with basic introduction of tested devices and standard testing conditions of electrical devices in the laboratory. Then following a description of the original evaluation software is made and its shortcomings are pointed out. The practical part is devoted to the creating in LabVIEW, implementation and verification of the functionality of the new evaluation software.
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