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MV Overhead Line Protections and their Coordination with Autoreclosers
Šoustal, Petr ; Skala, Petr (referee) ; Orságová, Jaroslava (advisor)
The aim of this Master’s Thesis is to describe protections for overhead lines in distribution networks. Here are described requirements for the protection and the basic protections. Protections are divided according to their protective function. For each protection is given its use and its power plans. It is stated in the work setting of protection in the real network. On this network is simulated place with short-circuit and described the action of protection. The work also deals with the coordination of protection with automatic circuit breakers. This chapter shows that, given the selectivity is not possible to deploy two or more reclosers (remotely-operated switches) to the core network management. The next chapter describes two representatives reclosers available on the Czech market OSM 27 and GVR 27. Chapter describes and compares their performance characteristics. Conclusion the work includes a proposal protected the lead in incorporating automatic circuit breakers (remotely operated circuit breakers and reclosers). The proposal is based on two different levels of annual number of interruptions and duration of annual general interruption of electricity supply. For these levels the company EGÚ Brno, a.s. proposed several variants of the use of remote-controlled in terms of reducing the cost of the penalty. Our task was to choose a variant that would be applicable in the real network. Reducing costs is feasible only in the limits Ln = 6 failures / year and Lt = 720 min / year, where the selected option No. 4. The limits Ln = 8 failures / year and Lt = 1,080 min / year, not in the real network may no option in terms of selectivity.
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Analysis and evaluation of technical systems of motor operators of circuit breakers
Hurbanič, Jakub ; Valenta, Jiří (referee) ; Dostál, Lukáš (advisor)
This bachelor thesis was created as a overview and analysis of drive systems for moulded case power circuit breakers. There si an introduction to motor operators and their possible use with remote control and use in future in name of digitalization and elektrification. Also there is listed an analysis of opertors depending on the method of installation, switching power and the operator itself i.e. electric motor or electromagnet. There is mentioned the possibilities of controll and power supply of these operators and the positions of circuit breaker. In the end a small market analysis is executed and a short chapter dealing with measurment of electric motor operator in OEZ s.r.o. company.
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Electrical installation in apartment buildings
Pírek, Ondřej ; Formánek, Marian (referee) ; Doležalová, Jana (advisor)
Bachelor thesis describes wiring system in apartment buildings. Theoretical part deals with legislation, main house conduit, wiring materials, heavy and low current, and also with Smart Homes. In this thesis, there is also an analytical part which is applied to specified building. In this section we have calculation for specific cable, design of wiring materails and calculation of the annual electric energy consumption. Third part includes project with technical report and attachment with drawings.
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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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Calculation of heat and force field UniGear ZS1
Mokrý, Lukáš ; ABB, Drahomír Tůma, (referee) ; Dohnal, Petr (advisor)
The aim of my work is to describe high-voltage switchgear type UniGear 500R, which is part of UniGear switchgears family. I will focus on heating issue of one 500R unit and its parts during operation. Maximum values of this heating is limited by standards and can´t be exceed to ensure safe and reliable operation. That is why the heating tests are necessary part of designing and developing switchgears. Calculation will be made by two different ways. First is classic one-pole heating net method and second is numerical simulation in Solidworks flow simulation program. Except the theoretical description there will be presented also used 3D model and explanation of both method, used to calculation and simulation. Last point of this work is measuring of this type of switchgear and getting real data. The main point there is to compare measured values with values calculated and decide if is possible to simulate tests with appropriate accuracy. Then would be also possible to substitute the real test in laboratory, which costs many thousand crowns and takes lots hours of time. This work is collaborated with EJF division of ABB Company, where I am employed. Heating issues in this company is always on process, because of developing and improving of their products. So this work could be helpful in this field. ABB provides all materials needed, especially technical catalogues, 3D model and final values from laboratory measuring. Support from college faculty is mainly in study consultations and proposing of calculations making. In the end of work will be make final comparison and evaluation of achieved results.
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FEM analysis of overcurrent trip unit
Makki, Zbyněk ; Augusta, Zbyněk (referee) ; Valenta, Jiří (advisor)
The aim of the project was to prepare the given model of the current path in the environment of the SolidWorks programme, in order to simulate the flow path in the environment of the Ansys programme, where there was calculated the distribution of current density,voltage drops and heat loss on the the specified current track according to specified conditions. The obtained results are analyzed at the conclusion of this work.
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EMC Test laboratory for low voltage circuit breaker
Vejtasa, Leoš ; Dřínovský, Jiří (referee) ; Dohnal, Petr (advisor)
Nowadays there are electronic systems almost in every new device. They are emitting and receiving electromagnetic interferences. The safety levels for circuit breakers are also increasing. Because of these issues the circuit breakers must work properly also in areas filled by electromagnetic interference. This thesis describes the issues of electromagnetic susceptibility of the circuit breakers.
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Design the Transformer Station for the Outgoing Power of Cogeneration Unit
Pastorek, Jaroslav ; Procházka, Aleš (referee) ; Orságová, Jaroslava (advisor)
The thesis deals with the design of a transformer station for the outgoing power of cogeneration unit with an electric capacity of up to 1 MW. The thesis describes the design procedure of individual devices such as a transformer with a nominal ratio 22/0,4 kV, high voltage switchgears and low voltage switchgears. With the proper selection of the transformer, along with the technical parameters, the economic benefits that come from its purchasing and operating costs with the transformer operation are also considered. Based on this, the economic comparison of selected types of oil transformers during 20 years is also developed. Another part of the thesis deals with HV and LV switchgears, which are dimensioned according to shortcircuit conditions in the transformer station. In conclusion this work deals with the grounding of a transformer station and design protection in accordance PPDS.
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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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