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Temperature and humidity influence on insulation resistance of electric motors
Fiala, Petr ; Vetiška, Vojtěch (referee) ; Ondrůšek, Čestmír (advisor)
The bachelor‘s thesis studies the effects of temperature and relative humidity on the insulation resistance of electric motors and their polarization index. The first chapter describes measuring principle of insulation resistance, measured objects, used measuring instruments and actual environmental conditions. The second chapter defines the basic requirements of insulation systems and there is especially solved evaluation of the measurement of individual parts of motors and calculation of polarization index. Third chapter discusses the influence of temperature and relative humidity on insulation resistance, there are formulated general preconditions and after using climate chamber there are presented measurement results on real motors in the industrial practice.
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Insulation system of synchronous and induction motors for 18kV
Šporcr, Viktor ; Vetiška, Vojtěch (referee) ; Ondrůšek, Čestmír (advisor)
Bachelor’s thesis is divided into two separate sections. First part is concentrated on insulation system of high voltage machines impregnated by vacuum pressure impregnation. This part of semester thesis concisely describes the composition of individual components used for construction insulation systems of air and water cooled rotation machines. Second practical part contains evaluation of dielectric resistance of coil set with insulation system designed for voltage level 18 kV. This part contains a short description of used insulations. Further includes a report of dielectric tests of used coil set. This set of coils was tested on following tests. Heating measurement semi conductive tape with infrared camera at impulse voltage. The coils was exposed to impulse voltage for one 100 hours and sinus voltage for one 1000 hours. Before and between, aging was measured value of charge partial discharges and dissipation factor.
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Simulation of hybrid car drive
Byrtus, Jiří ; Vetiška, Vojtěch (referee) ; Huzlík, Rostislav (advisor)
This thesis deals with analysis of electric drive parts from hybrid electric vehicle, namely interior permanent magnet synchronous motor and inverter with control. First part describes a basic theory. Further, motor and inverter computer models are shown, specified simulations are performed on this models. Results are compared with values measured on real machines from accessible literary sources.
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Calculation of DC electromagnet and its experimental verification
Steidl, Adam ; Vetiška, Vojtěch (referee) ; Valenta, Jiří (advisor)
Content of this thesis deals with electromagnets as operating elements in electric machines. Thesis is divided in two main parts, theoretical and practical. The theoretical part describes electromagnets as an electric machine, usage of electromagnets in electrical devices as operating element. Electromagnets are further divided in groups on the basis of different criteria. Next, the theory of electromagnetic fields and methods of assesment of static pull and dynamic characteristics are described. Construction and function analysis of researched type of electromagnet from OEZ company with permanent magnets, which serves as trigger in compact circuit breaker, is also included in this part. Practical part includes measurement of force quantities of an electromagnet in different operating states and its evaluation. For analysis of dynamic quantities with finite element method was created suitable three-dimensional model of electromgnet. Model is used for simulation ofdifferent operating states.The last part describes measurement of dynamic characteristics of the electromganetic system. This part is closed with comparation of results.
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Vibration Harvester for Aircraft Applications
Rubeš, Ondřej ; Vetiška, Vojtěch (referee) ; Hadaš, Zdeněk (advisor)
This thesis is focused on modification of a design proposal of a vibration energy harvester for autonomous aircraft applications. Vibration energy harvester is mechanism, which converts vibration energy to electric energy. Its main parts are oscillating mass, magnets and coil for electromagnetics induction. The thesis is consisted of simulations of magnetics circuits, creating 3D model of harvester and simulations of oscillations with parameters from 3D model, magnetics simulations and with input sample of exciting vibrations.
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Asynchronous dynamometer - power inverter
Vetiška, Vojtěch ; Červinka, Dalibor (referee) ; Klíma, Bohumil (advisor)
This project deals with the power converter for the asynchronous dynamometer. Inside of the document we shall acquaint with claims towards switching transistors and actuators. Furthermore we shall go through the principle and the wiring of three-phase converters and active rectifiers . We specify particular conditions of parameters for the power converter. For these conditions we shall dimension particular elements of the power converter. On the end we shall design the mechanical arrangement of the power circuit and create the design documentation..
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Derating on the low voltage devices with a thermal trip unit
Dobrovolný, Jakub ; Vetiška, Vojtěch (referee) ; Dostál, Lukáš (advisor)
Electrical devices are secured as not to injure living creatures via electric current and damage or destroy machinery due to the effects of electric current. Circuit breaker is a device responsible for protection of an electrical circuit against damage. The main aim of thesis is the correct function of the thermal trip unit when it exposes to the thermal warming. The thermal trip unit is depended on heating of a bimetal before overcurrent flow. The goal of thesis is temperature and voltage drop profile from measured values. Verification of the measurement is done in SolidWorks Flow Simulation software. According to simulations are determined currents for correct function of the thermal trip unit in different temperatures of an environment. The most important result of the thesis is correct setting of the operating current in the circuit breaker.
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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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Applying SolidWorks Flow Simulation for cooling system of the power converter
Matoušek, Patrik ; Vetiška, Vojtěch (referee) ; Dostál, Lukáš (advisor)
Thesis deals with the issue of cooling power converters. It describes the disposition of power converter M50, produced by ELCOM, a.s., and the distribution and origin of heat losses in the converter. The thesis then describes the process of creating a 3D CAD model of the converter in Solidworks and the procedure for heat simulation of the converter in default state and with cooling fan failures using Solidworks Flow Simulation. The thesis then evaluates the results of these simulations, and on their basis it suggests possible improvements in the design of converter‘s cooling system. These improvements are then evaluated in further simulations. The thesis then describes the verification of performed simulations by comparison with a temperature-rise test.
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Temperature and humidity influence on insulation resistance of electric motors
Fiala, Petr ; Vetiška, Vojtěch (referee) ; Ondrůšek, Čestmír (advisor)
The bachelor‘s thesis studies the effects of temperature and relative humidity on the insulation resistance of electric motors and their polarization index. The first chapter describes measuring principle of insulation resistance, measured objects, used measuring instruments and actual environmental conditions. The second chapter defines the basic requirements of insulation systems and there is especially solved evaluation of the measurement of individual parts of motors and calculation of polarization index. Third chapter discusses the influence of temperature and relative humidity on insulation resistance, there are formulated general preconditions and after using climate chamber there are presented measurement results on real motors in the industrial practice.
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