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Rerating on the low voltage devices with a thermal trip unit
Trubák, Vojtěch ; Valenta, Jiří (referee) ; Dostál, Lukáš (advisor)
This work is about bimetal trip unit used in circuit breakers. It focuses on how ambient temperature affects function of this tripping unit. In second chapter of this work, there are described thermal and dynamic effects of electric current. You can find there equations for calculation of temperature rise caused by electric current, its max temperature change and its process, also equations describing force, caused by electric current. In third chapter is short introduction of circuit breakers. There is description of their function, classification and construction. Finally there is description of residual current device. Fourth chapter of this work is focused on bimetals. There is described their function principle, ways of manufacture, used materials and its tripping characteristic. In fifth chapter, the circuit breaker 3VA12 is introduced, its electrical characteristics and its applications. Also, there is described principal of bimetal application as thermal trip unit. Sixth chapter is about procedure used to create model in CAD program Solidworks. You can find there individual pieces of current path and its addons connected together and forming model of circuit breaker. There are also showed modifications of the model, using thermal and conduction resistances. Last chapter is dedicated to results of rerating. There is final table showing correction koeficients of rated operational current and their comparison to real ones.
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Special small induction motor
Trubák, Vojtěch ; Mach, Martin (referee) ; Hájek, Vítězslav (advisor)
This term paper is focused on theory and calculation of an induction motor with solid rotor. It is divided into six chapters, the first one being an introduction and the last being a conclusion. Second chapter is dedicated to magnetism. There is briefly description of a skin depth of a conductor and calculation method for impedance of a conductive solid. Third chapter is focused on theory of an induction machines, their construction, equivalent circuit and some of their properties. Fourth chapter is dedicated to calculation of an induction motor with solid rotor and its parameters. Fifth chapter is comparing results of calculation done in fourth chapter for an already existing motor with measured values.
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Special small induction motor
Trubák, Vojtěch ; Mach, Martin (referee) ; Hájek, Vítězslav (advisor)
This term paper is focused on theory and calculation of an induction motor with solid rotor. It is divided into six chapters, the first one being an introduction and the last being a conclusion. Second chapter is dedicated to magnetism. There is briefly description of a skin depth of a conductor and calculation method for impedance of a conductive solid. Third chapter is focused on theory of an induction machines, their construction, equivalent circuit and some of their properties. Fourth chapter is dedicated to calculation of an induction motor with solid rotor and its parameters. Fifth chapter is comparing results of calculation done in fourth chapter for an already existing motor with measured values.
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Rerating on the low voltage devices with a thermal trip unit
Trubák, Vojtěch ; Valenta, Jiří (referee) ; Dostál, Lukáš (advisor)
This work is about bimetal trip unit used in circuit breakers. It focuses on how ambient temperature affects function of this tripping unit. In second chapter of this work, there are described thermal and dynamic effects of electric current. You can find there equations for calculation of temperature rise caused by electric current, its max temperature change and its process, also equations describing force, caused by electric current. In third chapter is short introduction of circuit breakers. There is description of their function, classification and construction. Finally there is description of residual current device. Fourth chapter of this work is focused on bimetals. There is described their function principle, ways of manufacture, used materials and its tripping characteristic. In fifth chapter, the circuit breaker 3VA12 is introduced, its electrical characteristics and its applications. Also, there is described principal of bimetal application as thermal trip unit. Sixth chapter is about procedure used to create model in CAD program Solidworks. You can find there individual pieces of current path and its addons connected together and forming model of circuit breaker. There are also showed modifications of the model, using thermal and conduction resistances. Last chapter is dedicated to results of rerating. There is final table showing correction koeficients of rated operational current and their comparison to real ones.
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