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Current distribution and heat losses in the low voltage circuit breakers
Musil, Pavel ; Janda, Marcel (referee) ; Makki, Zbyněk (advisor)
The work is focused on the calculation of decomposing the current and the thermal loss in circuit breakers of low voltage. In the work´s first half, there is a summary of the most frequently used circuit breaker elements with a focus on their constructional layout. The biggest attention is devoted to the circuit breaker marked LPN-16B by the company OEZ. A model of the under current trajectory of this specific element is created in a program Inventor on which the following calculation of decomposing the current and thermal loss was accomplished in a program Ansys. The obtained results are assessed in the conclusion of this work.
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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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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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Analysis of a bimetal release
Zelenka, Michal ; Augusta, Zbyněk (referee) ; Valenta, Jiří (advisor)
This master‘s thesis deals with the thermal overload trip unit in automatically operated electrical switching devices. The first part of this thesis serves as a basis for a design of thermostatic bimetal element in electrical switching device. The thesis presents important parameters and calculation principles needed for the design of bimetal element. The thesis further describes the operating principle of thermal trip unit and its possible design solutions. The main part is devoted to analytical calculation and measurement of specific thermostatic bimetal type contained in thermal trip unit of molded case circuit breaker. It is measurement of force and deflection, depending on temperature change. In the next part a numerical model of the bimetallic strip was created and its deflection was simulated. The analytical results are compared with the measured and simulated results at the end of the thesis.
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Simulation of circuit-breaker trip unit
Dostál, Lukáš ; Augusta, Zbyněk (referee) ; Valenta, Jiří (advisor)
Securing of electrical devices is important not only to protect against destruction under the effects of electric current, but also for protection of people or animals against electric shock. With increasing of living standards goes hand in hand increasing of the electricity consumption. Therefore In the grid of low voltage, there are increasing short-circuit currents. With improving technology is posed considerable demand on the performance, security and switching capacity of circuit breakers. This thesis is oriented on development of thermal and electromagnetic switch of circuit breaker on which is put a big demand in development of new types of circuit breakers. The thesis is interesting because of comprehensive use of circuits’ breakers since it can be used in AC and DC networks with frequency of 50 Hz and 400 Hz.
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Thermal overload trip unit in electrical switching devices
Marek, Stanislav ; Šimek, David (referee) ; Zelenka, Michal (advisor)
This bachelor thesis revolves around a time dependent thermal overload trip unit inside automated switching mechanisms. The first part addresses the principle of the function of a thermal overcurrent trip unit and the possible construction solutions. The biggest emphasis is given to bimetal as a base construction feature of the thermal overcurrent trip unit. Besides the materials that are most suitable for the creation of bimetal, various bimetal parameters that are needed for its design are also analyzed. The next subject of the thesis is an introduction to the elemental calculations for the bimetal component and the summary of mathematical relations for the calculation of the most commonly used solutions. A predominant part of this thesis revolves around the theoretical calculation of the thermal overload trip in a previously estabilished circuit breaker for a specific type of the bimetal and a specific required tripping characteristic. The previously estabilished calculation is then verified by measuring. The measuring itself consists of the measurement of the free bending of the bimetal in dependence on heat. The last part of this thesis includes the assessment of the results calculated from the theoretical standpoint, compared with the results given by the measurement.
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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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Thermal overload trip unit in electrical switching devices
Marek, Stanislav ; Šimek, David (referee) ; Zelenka, Michal (advisor)
This bachelor thesis revolves around a time dependent thermal overload trip unit inside automated switching mechanisms. The first part addresses the principle of the function of a thermal overcurrent trip unit and the possible construction solutions. The biggest emphasis is given to bimetal as a base construction feature of the thermal overcurrent trip unit. Besides the materials that are most suitable for the creation of bimetal, various bimetal parameters that are needed for its design are also analyzed. The next subject of the thesis is an introduction to the elemental calculations for the bimetal component and the summary of mathematical relations for the calculation of the most commonly used solutions. A predominant part of this thesis revolves around the theoretical calculation of the thermal overload trip in a previously estabilished circuit breaker for a specific type of the bimetal and a specific required tripping characteristic. The previously estabilished calculation is then verified by measuring. The measuring itself consists of the measurement of the free bending of the bimetal in dependence on heat. The last part of this thesis includes the assessment of the results calculated from the theoretical standpoint, compared with the results given by the measurement.
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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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Current distribution and heat losses in the low voltage circuit breakers
Musil, Pavel ; Janda, Marcel (referee) ; Makki, Zbyněk (advisor)
The work is focused on the calculation of decomposing the current and the thermal loss in circuit breakers of low voltage. In the work´s first half, there is a summary of the most frequently used circuit breaker elements with a focus on their constructional layout. The biggest attention is devoted to the circuit breaker marked LPN-16B by the company OEZ. A model of the under current trajectory of this specific element is created in a program Inventor on which the following calculation of decomposing the current and thermal loss was accomplished in a program Ansys. The obtained results are assessed in the conclusion of this work.
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