Sendo as interrupções, os afundamentos de tensão e as sobretensões distúrbios de Qualidade de Energia Elétrica (QEE) com potencial de grande impacto econômico, estudos que procuram alternativas de mitigação de seus efeitos ou prevenção de sua ocorrência têm sido amplamente realizados nas últimas décadas. Uma das metodologias de avaliação de sua ocorrência é realizada pela predição, que geralmente se concentra em simulações de faltas em parcelas de sistemas elétricos de potência. Nos Procedimentos de Distribuição de Energia Elétrica no Sistema Elétrico Nacional (PRODIST), encontra-se a denominação geral de Variações de Tensão de Curta Duração (VTCD) para estes três tipos de distúrbios, os quais podem ser classificados tanto por sua magnitude quanto por sua duração. Nesse contexto, este trabalho avalia pela predição a influência exercida pela conexão e o aterramento do neutro de transformadores trifásicos nas quantidades de VTCD, especialmente de afundamentos de tensão, e no valor do índice Fator de Impacto (FI) do PRODIST, que são observados em um nó com conexão a um consumidor industrial Realizam-se estudos de caso sobre um sistema de potência simulado no software Alternative Transients Program (ATP), o qual possui dois transformadores em sua rede: um transformador da subestação e outro na entrada do nó do consumidor industrial. Consideram-se duas conexões possíveis para o transformador de entrada, e aplica-se uma resistência de aterramento para o neutro de ambos os transformadores em cada caso, alteram-se o seu valor. Verificam-se as tensões no nó do consumidor industrial de duas formas diferentes: tensões fase-terra e tensões fase-fase. Observa-se, assim, que há diferenças para estas quantidades e para o valor do FI devidas à forma de conexão do transformador de entrada, valor da resistência de aterramento de neutro de ambos os transformadores e formas de verificação das tensões. / Since interruptions, voltage sags and overvoltages are Power Quality (PQ) disturbances with great economic impact potential, studies that seek alternatives to mitigate its effects or to prevent its occurrence have been done widely in the last decades. One of the methodologies to assess its occurrence is performed by prediction, which usually focuses on power systems fault simulations. In the Brazilian norm of PQ, there is the general designation short duration voltage variation (VTCD) for these three types of disturbances, which are classified both in terms of magnitude and duration. In this context, this work assess by the prediction the influence of three-phase transformers winding connection and neutral grounding in the quantities of VTCD, especially voltage sags, and in the index value Impact Factor (FI) of the Brazilian regulation standard, which are observed in a node with connection to an industrial consumer. The case studies are performed on a simulated power system in the Alternative Transients Program (ATP), which has two transformers in its network: one substation transformer and another at entrance of the industrial consumer node. Two possible winding connections are considered for the entrance transformer, and a ground resistance is applied to the neutral of both transformers in each case, being changed their value. Voltages in the industrial consumer node are verified by two different ways: phase-to-ground voltages and phase-to-phase voltages. It is observed that there are differences for these quantities and for the value of the FI due to the winding connection of the entrance transformer, the value of the neutral ground resistance of both transformers and the ways of voltage verification.

Made available in DSpace on 2014-10-09T12:25:54Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:39Z (GMT). No. of bitstreams: 0 / Neste trabalho avaliou-se experimentalmente a influência da onfiguração de bobinagem no comportamento mecânico de cilindros de compósito polimérico com bobinagem simétrica e assimétrica. Para tanto, foram fabricados pelo processo de bobinamento filamentar (filament winding) dois grupos de cilindros com extremidades abertas, que apresentaram alteração no posicionamento das camadas em relação ao plano médio, caracterizando laminados simétrico e assimétrico. No compósito deste estudo, utilizou-se uma matriz com sistema tricomponente com resina epoxídica e reforço de fibra de carbono. Para avaliação da resistência mecânica, os cilindros foram submetidos a ensaio hidrostático que consistiu da pressurização interna em dispositivo apropriado mediante a utilização de um fluido até que ocorresse o colapso. Adicionalmente, as deformações e os modos de falha dos dois grupos de cilindros foram analisados e comparados. A utilização de um programa de cálculo de elementos finitos permitiu concluir que esta ferramenta, muito usada em projeto, não consegue identificar tensões na orientação da fibra em cada uma das camadas do compósito, bem como tensões de cisalhamento interlaminares que surgem nos cilindros com configuração assimétrica. Os resultados dos ensaios mostraram que as configurações de bobinagem exercem influência no comportamento mecânico dos cilindros de material compósito, favorecendo a construção do tipo simétrica. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Ce travail de thèse s’est déroulé dans le cadre du projet de nanolanceur à propulsion hybride PERSEUS du CNES. La performance de ce concept est influencée par l’allègement de la structure du lanceur. La voie de développement qui a été choisie est de supprimer le liner du réservoir composite cryogénique. Elle repose sur trois exigences fonctionnelles : la compatibilité du matériau composite avec l’oxygène liquide (LOX), l’étanchéité du réservoir, et la résistance aux sollicitations thermomécaniques.L’étude de la compatibilité LOX des matériaux composites met en évidence l’importance du transfert de chaleur au sein du composite et plus précisément de la conductivité thermique des fibres. Ce résultat théorique est conforté par l’expérimentation.Le verrou scientifique principal du travail de thèse concerne l'influence de l’endommagement du composite sur la perméabilité de ce dernier. La conception de dispositifs expérimentaux a permis de déterminer l’évolution des endommagements (fissuration transverse, micro-délaminage, ouverture de fissure) et celle de la perméabilité. Un modèle complet de prévision de la perméabilité d’une paroi composite sollicitée thermo-mécaniquement est proposé. Il s’articule autour d’un modèle d’endommagement à l’échelle du pli, d’un modèle de prédiction de l'ouverture des fissures, et d’un modèle d’écoulement en milieu poreux. La pertinence du modèle développé est testée à travers la réalisation d’un démonstrateur technologique sans liner et d’une campagne d’essais d’endommagement et de mesure de perméabilité. / This thesis deals with hybrid propulsion launcher systems studied by the CNES (Centre National d'Etudes Spatiales). The performance of the launcher implies its lightening and in this work, the use of a cryogenic composite linerless tank is evaluated. Three functional requirements must be satisfied: the compatibility between the composite material and the liquid oxygen (LOX), the tank gas-tightness and the strength under pressure.The LOX compatibility of composite materials implies high thermal conductivity of the composite, and consequently of the fiber reinforcement. This theoretical result is confirmed by experiments.The main scientific challenge concerns the damage influence on the composite permeability. Specific experimental devices allow determining the damage evolution (transverse cracking, delamination, opening crack) and the composite permeability. A predictive composite permeability model is applied to a composite wall under thermomechanical load: this model includes a ply-scale damage model, a predictive opening crack model and a model of flow through porous media. The relevance of the model is validated through the realization of a linerless prototype tank and the associated tests which correlate damage and permeability.

Mica/Epoxy machine insulation is a composite material of the mineral mica, fibre-glass mesh and epoxy resin. The material is used in motors and generators rated for high voltage, where the material must withstand multiple stresses such as elevated temperatures, mechanical and electrical stresses. This is a novel investigation that focuses on the breakdown mechanisms related to electrical stress of the insulation. These include partial discharges and electrical treeing. The micro Computed Tomography (μCT) uses a series of X-ray images to visualise the interior. This provides a method for non-invasively examination of the insulation for any signs of material degradation caused by high electrical fields. The following thesis presents an initial study on how this material system interacts with the μCT, the production of 16 samples capable of being electrically aged and scanned in the μCT, with minimal interference, sample preparation and an analysis of the images produced from the μCT. The samples produced are electrically aged at different voltages after which they are scanned with the μCT. The images produced are then analysed for signs of material degradation using different software. Some of the samples did have a complete electrical breakdown and an attempt of correlating these breakdowns to the amount of folds in the insulation is done. It is found that samples with an aluminium core are suitable for μCT imaging. The visualisation of defects such as voids, resin rich parts or folds in insulation is also possible. The detection of material degradation due to electrical aging is not clear enough to draw any conclusions although some possible signs are found. For samples that had an electrical breakdown the result is much clearer. It shows the breakdown channels path inside the insulation, moving in between the mica tape layers. The samples with a complete breakdown also had tendencies that the breakdown channels followed the resin rich part in the sample. Even if no signs of electrical treeing can be seen in the samples during aging, the breakdown channels visualised still show what path the final treeing did take and how it did so by moving around the mica tape.

abstract Aim of this Master's Thesis is to describe the process of liquidation to the reader step by step from winding-up of the company to its dissolution and focus on prospective problems that might arise in connection therewith. Based on the valid legislation the theoretical part deals with basic terms and explanation thereof with regards to anticipated effectiveness of the New Civil Code and Act on Business Corporation in January 2014 and changes related thereto. The practical part contains description of the liquidation process of the fictitious limited liability company. Key words: liquidation, liquidator, winding-up and dissolution of the company

Sendo as interrupções, os afundamentos de tensão e as sobretensões distúrbios de Qualidade de Energia Elétrica (QEE) com potencial de grande impacto econômico, estudos que procuram alternativas de mitigação de seus efeitos ou prevenção de sua ocorrência têm sido amplamente realizados nas últimas décadas. Uma das metodologias de avaliação de sua ocorrência é realizada pela predição, que geralmente se concentra em simulações de faltas em parcelas de sistemas elétricos de potência. Nos Procedimentos de Distribuição de Energia Elétrica no Sistema Elétrico Nacional (PRODIST), encontra-se a denominação geral de Variações de Tensão de Curta Duração (VTCD) para estes três tipos de distúrbios, os quais podem ser classificados tanto por sua magnitude quanto por sua duração. Nesse contexto, este trabalho avalia pela predição a influência exercida pela conexão e o aterramento do neutro de transformadores trifásicos nas quantidades de VTCD, especialmente de afundamentos de tensão, e no valor do índice Fator de Impacto (FI) do PRODIST, que são observados em um nó com conexão a um consumidor industrial Realizam-se estudos de caso sobre um sistema de potência simulado no software Alternative Transients Program (ATP), o qual possui dois transformadores em sua rede: um transformador da subestação e outro na entrada do nó do consumidor industrial. Consideram-se duas conexões possíveis para o transformador de entrada, e aplica-se uma resistência de aterramento para o neutro de ambos os transformadores em cada caso, alteram-se o seu valor. Verificam-se as tensões no nó do consumidor industrial de duas formas diferentes: tensões fase-terra e tensões fase-fase. Observa-se, assim, que há diferenças para estas quantidades e para o valor do FI devidas à forma de conexão do transformador de entrada, valor da resistência de aterramento de neutro de ambos os transformadores e formas de verificação das tensões. / Since interruptions, voltage sags and overvoltages are Power Quality (PQ) disturbances with great economic impact potential, studies that seek alternatives to mitigate its effects or to prevent its occurrence have been done widely in the last decades. One of the methodologies to assess its occurrence is performed by prediction, which usually focuses on power systems fault simulations. In the Brazilian norm of PQ, there is the general designation short duration voltage variation (VTCD) for these three types of disturbances, which are classified both in terms of magnitude and duration. In this context, this work assess by the prediction the influence of three-phase transformers winding connection and neutral grounding in the quantities of VTCD, especially voltage sags, and in the index value Impact Factor (FI) of the Brazilian regulation standard, which are observed in a node with connection to an industrial consumer. The case studies are performed on a simulated power system in the Alternative Transients Program (ATP), which has two transformers in its network: one substation transformer and another at entrance of the industrial consumer node. Two possible winding connections are considered for the entrance transformer, and a ground resistance is applied to the neutral of both transformers in each case, being changed their value. Voltages in the industrial consumer node are verified by two different ways: phase-to-ground voltages and phase-to-phase voltages. It is observed that there are differences for these quantities and for the value of the FI due to the winding connection of the entrance transformer, the value of the neutral ground resistance of both transformers and the ways of voltage verification.

The ability to withstand a short circuit is the most essential feature of a power transformer. The most important reason to design short-circuits proof transformers is to ensure the reliability of the power grid (avoiding black outs etc.) and safety (fire and explosion in case of failure). During short circuit, the most effected winding is the LV winding due to the flow high currents even during the normal working condition. So during a short circuit large forces are generated which act on the winding and these forces can reach hundreds of tons in fraction of a second, so the transformer must be properly designed in order to withstand these forces or the transformer can fail in different ways. One of the possible failure modes called “Spiraling” is discussed and analyzed in this thesis. Spiraling Occurs when the LV winding twists tangentially in the opposite direction at the ends due to radial short circuit forces. From literature study the transient forces acting on the winding during a 3-phase short circuit was determined and these transient forces were used to perform simulations on the model. The axial and radial forces applied on the model were such that it has a uniform magnitude per each turn. Various analysis was performed on the model which includes the Static, Modal and Transient Structural analysis in Ansys Workbench and each analysis involved parametric analysis where the deformations and the torsional mode shapes were determined

Die Steigerung der elektromagnetischen Ausnutzung elektrischer Maschinen ist im Wesentlichen durch eine Erhöhung des Strombelages möglich. Die Belastungsgrenze resultiert u. a. aus der maximal zulässigen Temperatur der Wicklungsisolation. Aus der geringen spezifischen thermischen Leitfähigkeit herkömmlicher Isolierwerkstoffe resultieren große Temperaturgradienten im Wicklungsquerschnitt und es kommt zur Bildung von Hotspots z. B. in den Wicklungsköpfen. Im Beitrag werden die Entwicklung und die Charakterisierung von Polysiloxan-Kompositen mit keramischen Füllstoffen vorgestellt. Im Vergleich zu herkömmlichen Isoliermaterialen kann die spezifische thermische Leitfähigkeit damit etwa um den Faktor fünf gesteigert werden. Die Materialien werden für die Herstellung der Hauptisolation des Elektroblechpaketes in einem Tauchprozess sowie die Vakuum-Imprägnierung der Wicklung eingesetzt. Für einen elektrischen Radnabenantrieb werden die erwartete Wicklungstemperaturreduzierung und die daraus resultierende mögliche Leistungsdichtesteigerung diskutiert. / The increase of the electromagnetic utilisation of electrical machines is essentially achievable by increasing the electric load. The power limit results from the maximum permissible temperature of the winding insulation. The low specific thermal conductivity of conventional insulating materials results in large temperature gradients in the winding cross section and the appearance of hotspots in the end windings. The paper discusses the development and characterisation of polysiloxane composites with ceramic fillers. Compared to conventional insulating materials, therewith the specific thermal conductivity can be increased by a factor of five. The materials are used for the production of the main insulation of the laminated core in a dipping process and the vacuum impregnation of the winding. For an electric wheel hub motor, the expected winding temperature reduction and the possible power density increase are discussed.

This master's thesis considers by single-phase asynchronous motor. The first part discuss about construction, principle of operation and basic parameters of this motor type. It also discussed the emergence of torque and torque characteristics of the different types of engines. The second part explains the basic ways of obtaining grip moment including outline the principles of functions particulars constructions types, which is produce in practice. In the third part is minutely analyse single-phase asynchronous motor with auxiliary phase and permanently conect capacitor, including method of assign size of a capacitor. Fourth part section provides the principles of the procedure for calculating basic parameters of the single asynchronous motor with auxiliary phase. At the last part is accomplished a calculation of single-phase asynchronous motor with permanently conect capacitor at auxiliary phase including comparation with already manufacturing motor.

This master´s thesis treats of all asynchronous motor. The project is about type and distribution motors, about differences between three-phase and single-phase machines and efficiency. In one of the chapters describes a particular type of engine with all the parametersfrom the manufacturer. This engine is completely analyzed and it is measured in detail. Then the project deals with the division, the calculation of losses and subsequent possibilities to increase the efficiency of induction motor. In the last chapter is calculation of single-phase motors, based on the engine produced.