Thesis (M.S.)--University of Wisconsin--Madison, 1964. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 72-74.

Portion of Thesis (PH. D.)--University of Michigan, 1942. / Two articles, by A.L. Ferguson and M.B. Towns, reprinted from the Transactions of the Electrochemical Society, v. 82, 1942. "Resumen del artículo" at end of each part.

Portion of Thesis (PH. D.)--University of Michigan, 1938. / Two articles, by A.L. Ferguson and H. Bandes, reprinted from the Transactions of the Electrochemical Society, v. 81, 1942. "Resumen del artículo" at end of each part. Includes bibliographical references.

Hydropower plants contains a lot of vital electrical power technology such as generators and transformers. To prevent damage to this equipment due to overvoltage, they are often protected by surge arrester and in some cases also by surge capacitors. The design and dimension of these components vary between different sites and regions and are often done using a template without considering the actual conditions of the site. In this thesis Simulink and Simscape Power System are used to study the case when a hydropower station is exposed to overvoltage. One of Fortum’s hydropower stations is simulated when being exposed to lightning and switching overvoltage to see how the existing overvoltage protection handles this stress. The results show that the surge arresters mounted in front of the generator managed to keep it safe for all overvoltage scenarios it is exposed to. They also shows that the surge capacitors mounted in front of the generator reduces the gradient of the overvoltage surge. However, as the surge arresters already keeps the overvoltage at safe levels, there is no need of reducing the overvoltage gradient and the surge capacitors becomes excessive in this particular hydropower plant. / Vattenkraftverk innehåller många vitala komponenter så som generatorer och transformatorer. För att skydda dessa oftast väldigt dyra komponenter mot överspänningar, används ventilavledare och ibland också överspänningskondensatorer. Utformning och dimensionering av skydden varierar mellan olika anläggningar och regioner. Dimensioneringen av skydden görs ofta schablonmässigt, utan någon väsentlig anpassning till de faktiska förhållandena. I detta examensarbete används simuleringsverktyget Simulink tillsammans med tillägget Simscape Power Systems för att simulera vad som händer när ett vattenkraftverk utsätts för olika överspänningar. Ett av Fortums vattenkraftverk studeras när det utsätts för blixt- och kopplingsöverspänningar för att se vad ventilavledarna samt överspänningskondensatorerna i denna anläggning fyller för funktion. Resultaten visar att ventilavledarna monterade framför generatorn klarar av att hantera alla överspänningar de utsätt för under simuleringarna. Resultaten visade också att överspänningskondensatorerna monterade framför generatorn sänker spänningsgradienten, men eftersom ventilavledarna redan håller spänningen på en säker nivå blir överspänningskondensatorerna överflödiga i denna station.

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It can not always be expected that ferroresonance happens.The ferroresonance is rarely seen on the nonlinear resonance of the power system. If the resonance is transient or steady it may result in overvoltage and over current and also degrade insulation of the equipment. It¡¦s been proved that the rare nonlinear resonance causes some unexplainable damages. Due to increasing power capacity, expanding transmission line and underground line of ferroresonance is increased. This thesis presents the three phase power system with analysis. The magnetic curve was obtained from field measurements and using many kinds of parameters which are from the magnetization characteristic and lines to analysis. Especially emphasized is the width of the hysteresis loop and the effects of magnetic hysteresis in the change of the operating point of the transformer. In the simulation, the thesis compares the effects of magnetic hysteresis with the non-effects of magnetic hysteresis, and compare the differences of parameter critical point to avoid ferroresonance. This thesis has presented some results in investigating the impact of different sets of initial condition on the models of behavior of a ferroresonance circuit.

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Hydrogen gas is the cleanest fuel which produces only water as a combustion product with no greenhouse or toxic gases. The combustible hydrogen fuel is an energy carrier but not an energy source. As an element, hydrogen is widely available in nature as a component of water and of hydrocarbons. An energy source is needed to extract the element from these compounds and convert it to the combustible hydrogen gas. Today, the energy source for nearly all hydrogen production is fossil fuel, principally natural gas. The supply of natural gas is limited and its price is increasing. Greenhouse gas and air pollutants are emitted when natural gas is used. Electrolytic extraction of hydrogen from water can overcome these stated problems but is more expensive with the present price of natural gas. Manufacturing the hydrogen with a valuable co-product would address this cost disadvantage. Sulfuric acid is a valuable chemical that is produced in large quantities. This research project helps to develop a procedure for extracting hydrogen from water while producing sulfuric acid as a co-product. An electrochemical cell was designed and developed for the production of hydrogen which uses sulfuric acid as electrolyte. In this electrochemical cell with sulfuric acid as an electrolyte we produce hydrogen at the negative electrode while the positive electrode is bathed in sulfur dioxide which it oxidizes to sulfuric acid. The sulfuric acid is collected at the bottom of the cell as valuable co-product. The presence of SO2 to scavenge the anode substantially reduces the equilibrium voltage required for the direct dissociation of water into hydrogen and oxygen. Various design parameters and the fabrication of the reactor are discussed briefly in the thesis. Experimental results of hydrogen production and current voltage curves are discussed. Sulfuric acid corrosion of cell materials is also discussed.

Orientador: Jacobus Willibrordus Swart / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-06T23:47:41Z (GMT). No. of bitstreams: 1 Orio_RobertoLacerdade_M.pdf: 1305384 bytes, checksum: e0e89b803f3ba5496d25f456a5f047dd (MD5) Previous issue date: 2006 / Resumo: Este trabalho tem como objetivo o projeto de um dispositivo supressor de surto de tensão para aplicação na proteção de equipamentos de telecomunicações. O projeto foi realizado com a utilização de programas de simulação. Os diversos parâmetros físicos, como dopagens e dimensões, assim como estruturas com e sem emitter-shorts foram estudadas para o entendimento da sua influência na operação do dispositivo supressor e estabelecer em que condições o seu melhor desempenho é obtido. Com base nos resultados adquiridos foi desenvolvido um processo de fabricação suficientemente simples para se aplicar em linha de produção. O dispositivo final proposto apresentou uma tensão de breakover de 250 V quando submetido a um pulso de corrente de 100 Alcm2. Após o chaveamento, a distribuição mais uniforme da densidade de corrente foi observada para uma estrutura com emitter-shorts não-centralizados em relação à área dos emissores do dispositivo / Abstract: This work intends to design a voltage surge suppressor device for telecommunications equipments. The project was conducted with the help of simulation tools. The physical parameters like dopings and dimensions, as well as structures with and without emitter­ shorts were studied in order to understand their influence on the device behavior and to establish in which conditions its best performance is obtained. Based on these simulation results, a simple fabrication process for line production was developed. The final device presented a breakover voltage of 250 V when a current pulse of 100 Alcm2 was applied. After the device turn-on the most uniform distribution of current density was observed for a structure with emitter-shorts non-centralized on the emitter device area / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica