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Change of voltage at LV terminals of a MV/LV power distribution transformer caused by changes in its load
Jandora, Jiří ; Bátora, Branislav (referee) ; Blažek, Vladimír (advisor)
The thesis deals with the use of distribution transformers, their integration into the electrical network, their properties, and principles and means of regulation according to changes in load. The introductory chapter is devoted mainly to the theoretical background concerning the functioning of the transformers. Even though it is not the focus of this thesis, a brief summary of their structure will be provided because it is presumed that not all the readers are familiar with this particular electrical network block and thus they should be explained how the transformer works. Then the ways of transformer regulation will be outlined. In the theoretical part, the important point for the reader is the substitution of the transformer by two-port network i.e. the equivalent circuit. The two-port network is a substitution of the connection properties by simple electric elements, which are not so problematic for further use. When dealing with the two-port networks in the chosen equivalent circuit, Blondel’s constants will be used. Blondel’s constants facilitate working with the basic network invariables of the circuit such as amperage, voltage and power. The second part of the thesis is devoted to solving a problem that involves the use of distribution transformers. The problem is as follows: there is a manufacturing plant with three transformers, each of them having rated power and nominal transformation ratio. The manufacturing plant is supplied by HV three-phase line with rated voltage and parameters given by the distribution point, where constant voltage is maintained. The task is to determine in what ways the voltage of the low voltage terminals of the transformers will change when changing the power from idling circuit to the rated load. The power factor should be constant. The method for solving this task has already been outlined in the theoretical part. The results are summed up in a simple chart completed with diagrams, which concisely describe the result of the research.
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3D CAD systems used in the field of electrical apparatuses
Makki, Zbyněk ; Krejčí, Jan (referee) ; Valenta, Jiří (advisor)
The aim of this project is to describe and compare individual 3D CAD systems and data format used in the area of construction and technical support in agreement with factual needs of project submitter company OEZ, Ltd. Fulfilment of 3D CAD systems background research which are used in the area of design of the electrical switchboards LV. Description of the main possibilities, that the particular system offers. Supported data format for export and import are mentioned too.
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Meter of powerline quality
Samek, Martin ; Horský, Pavel (referee) ; Kolka, Zdeněk (advisor)
The subject of graduation thesis is a design of line analyser according to standard EN61000-4-30 class A. The analyser is determine to be used for quality control of supplied electric power which is, during electric power transmission, affected by several disturbances. Power line analyser should measure single-phase and three-phase network parameters in LV and HV systems. Measured parameters can be shown on the full colour TFT display, stored in the device memory or sent to other devices such as PC. For communication between the device and PC the USB, Ethernet or RS485 interface are used.
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Evaluation of MV/LV network earthing systems
Sítař, Martin ; Topolánek, David (referee) ; Kopička, Marek (advisor)
This master's thesis deals with the measurement of grounding systems in HV/LV distribution networks, which includes grounding system of distribution substation and transmission lines. Explores the issue and principles for the measurement of parameters, which are important for the protection of persons and animals in order not to touch exposed conductive part accidentally, protection of electrical machines and equipment against high fault current and dangerous surges while the correct function of the connected electrical equipment is maintained. These parameters include earth potential rise, ground resistance, soil resistivity, touch voltage, step voltage and transferred potential to the LV network. The aim of this work is the preparation, analysis and subsequent evaluation for the real measurement in practice. These earthing-system measurements were carried out at the distribution station and the concrete pole with a section disconnector. Then a numerical model of the grounding system of concrete pole was created in ANSYS. Subsequent evaluation of the results as numerical terms (comparison measurements and simulated results) and evaluation in terms of analytical (measurement results compliance with the standard) including the numerical model of the earthing system is solved in the practical part of the master's thesis.
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Application of overvoltage protection in LV networks
Knebl, Jan ; Novotný, Jan (referee) ; Bátora, Branislav (advisor)
This paper describes the design of surge protection for objects of civil construction. The aim of this paper is to acquaint the reader with the problems of this region, which is nowadays especially for houses neglected. The introductory part of the thesis is focused on the theoretical analysis of the problem and become familiar with the standards in force, without which a person moving in this field certainly can not do. In the first major section is a repartition surge in general terms. In the second chapter, a repartition of surge protection on the inside and outside and a description of the individual components of these protections. The third chapter is made complete design protection for the school building, the first step is an analysis of the risks to unprotected building, then the protected and ultimately design of internal and external surge protection. In the last chapter, a check is made of the risk analysis using DEHN Support.
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Electric fault arc detection in LV network
Dubský, Martin ; Fencl, Jiří (referee) ; Dostál, Lukáš (advisor)
This thesis deals with arc detection using AFDD. Here is explained the general theory of electric arc. It also describes the principle of operation of the AFDD device, a specific type of instrument from OEZ s.r.o. and describe the test procedure for this instrument according to the technical standard. In the practical part, selected tests are performed and verified the function of the AFDD device in the event of a disturbance electric arc in the circuit.
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Evaluation of possibilities for voltage control in a LV distribution network
Bolgár, Robert ; Drápela, Jiří (referee) ; Topolánek, David (advisor)
This paper deals with possible ways of voltage regulation. Theoretical part includes a search of published methods and the available voltage regulators. Acquired theoretical knowledge has been applied in the development of mathematical models of two selected controllers applied to the testing network. The result of this work is a summary of the outcomes of dynamic simulations with two selected regulators at various locations in testing network. Comparing the results of dynamic simulation for two selected states was chosen the most appropriate regulator and its optimal location in testing network.
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Measurement of basic electrical variables on drives of LV circuit breakers
Mazálek, Tomáš ; Valenta, Jiří (referee) ; Bušov, Bohuslav (advisor)
This thesis has been created for the purpose of comparing calculated values by oscilloscope and by Excel. For this it was necessary to show a theory of electrical values of non-sinusoidal and aperiodic signal. There has been shown the methods of measuring of power consumption on motor operator for acquisition of relevant data. My thesis brings a wide overview, which is connected with motor operators. I am analyzing a principle of motor operator, methods of right measuring and I am describing a transfer of kinetic energy from driving motor to contacts of circuit breaker.
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Proposal of the reconstruction of 0,4 kV distribution network in a specific area
Fojtík, Martin ; Beneš, Jan (referee) ; Blažek, Vladimír (advisor)
This Master’s thesis deals with the problem of distribution electrical network with a focus on solving the steady operation of the electrical distribution network for E.ON Brno - Lisen. The calculation is made by using BIZON PAS Off-Line. The first part of thesis is specialized on the distribution of individual LV and MV networks.The second part of thesis is specialized on the general calculation of the steady operation distribution network and describe criteria for the design and evaluation of this network. In the practical part is calculate existing network in selected area in which is located 53 distribution transformers. In the final part is evaluate the status of existing network and perform design optimization and assessment of this network.
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