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1
Al-Kindi, F. J. "A model for impulse breakdown of SF6̲." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382317.
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Quenin, Alexandre. "Etude des propriétés diélectriques des mélanges azote-SF6 à faible taux de SF6." Grenoble INPG, 2002. http://www.theses.fr/2002INPG0154.
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Zhang, Quan. "Modelling of turbulent SF6 switching arcs." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2013339/.
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There is an overwhelming experimental and theoretical evidence indicating SF6 arc burning in a supersonic nozzle (known as the switching arc) is turbulent and in local thermodynamic equilibrium (LTE). Such an arcing arrangement is commonly used as the interrupter in gas blast circuit breakers. In order to reduce the development cost of gas blast circuit breakers, it is highly desirable to predict the arc behaviour under the operational conditions encountered in a power system. The major difficulty in achieving full computer aided predictive design of gas blast circuit breakers is the satisfactory prediction of the thermal interruption capability of an arc under turbulent conditions. Mathematical modelling of turbulent SF6 switching arcs, thus, forms the subject matter of this thesis. The approach for the modelling of turbulent switching arcs is similar to that for turbulent shear flows due to a direct resemblance between a nozzle arc and a round free jet both of which are dominated by shear flow. The conservation equations for switching arcs are, therefore, derived using Reynolds’s approach. The closure of these equations is based on the adoption of Boussinesq assumption to relate Reynolds stress to the time averaged velocity gradients through eddy viscosity. The turbulent heat flux is assumed to be related to Reynolds stress through a constant turbulent Prandtl number. Additional equations are introduced to determine the turbulence length scale and velocity scale required by eddy viscosity, which are provided by turbulence models. There are numerous turbulence models but none of them are specifically devised for switching arcs. The objective of the present investigation is, therefore, to choose relevant turbulence models to model turbulent SF6 switching arcs. Our choice of turbulence models is restricted to those which have been applied with success to similar flow conditions as those of a switching arc as well as their suitability for engineering application. We therefore choose the standard k-epsilon model and its two variants (the Chen-Kim model and the RNG model) for the modelling of SF6 turbulent switching arc. Since the application of the Prandtl mixing length model to SF6 switching arcs has met considerable success, this turbulence model is included in our investigation for comparison. In order to demonstrate the effects of turbulence, results based on laminar flow model are presented. Therefore, altogether five flow models have been used to study the nozzle arcs. Computational results are obtained by the five flow models under a wide range of discharge conditions in terms of different nozzle geometries, the rate of change of current (di/dt) before current zero and the stagnation pressure (P0). A detailed analysis of the physical mechanisms encompassed in each flow model is given to show the adequacy of a particular model in describing the rapidly varying arc during current zero period. The computed values of the critical rate of rise of recovery voltage (RRRV) are compared with corresponding measurements. It is found that RRRV predicted by laminar flow model is a few orders of magnitude lower than that measured, which indicates that turbulence plays a decisive role in the determination of thermal interruption capability of a nozzle arc. Of the four turbulence models, the Prandtl mixing length model gives the best prediction of RRRV when compared with experimental results. The drawback is that the value of the turbulence parameter of the Prandtl mixing length model needs to be derived from one test result for a given geometry. With our current understanding of the physics of turbulent arcs, the Prandtl mixing length model is the only turbulence model which can be used to predict the thermal interruption capability of a nozzle arc arrangement.
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Ijumba, N. M. L. "Non-uniform field breakdown in mixtures of SF6̲ and freon 113." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382321.
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Ashraf, Huma. "Anisotropic etching of silicon using SF6 plasmas." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404383.
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Lederle, Christoph. "Isoliervermögen SF6-isolierter Elektrodenanordnungen mit dielektrischer Beschichtung." Düsseldorf VDI-Verl, 2009. http://d-nb.info/992593530/04.
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Cai, Xiaolei. "Elimination of SF6 from transmission system equipment." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/elimination-of-sf6-from-transmission-system-equipment(4288ba94-8bcb-4805-94ab-5235fca5b94c).html.
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Sulphur hexafluoride gas is the dominant insulation and interruption material in high voltage gas insulated substation. Its usage remains a concern of transmission system operators owing to the global warming potential of the gas. The work carried out in this thesis aims to find the environment-friendly materials that can replace SF6. These candidates are required to have a strong dielectric strength for high voltage busbar insulation and well arc extinguishing capability necessary for high voltage circuit breaker.A range of alternative insulation types including CF3I gas and its mixture, high pressure air and solid insulating foam are considered as substitute of SF6. Theoretical studies on the dimensions of busbars used in substations are carried out for these options. The dimension of the dielectric system and its ampacity of respect system are calculated using heat transfer models considering their boiling point and proper working pressure which is related with the dielectric strength of some gas.On the other hand, SF6 gas circuit breaker is extremely popular on the medium and high voltage power networks owning to its effective arc extinguishing performance. It would be ideal if a substitute material could be found for SF6 as an interruption material. Biodegradable oil PTFE ablation, other gas candidates including N2, CF3I are investigated as possible replacement of SF6 through literature study.The usage of vacuum circuit breaker is eventually capable to operate in high voltage transmission system. Simulations have been carried out with software ATP/EMTP to investigate the influence of different characteristics of vacuum circuit breaker including chopping current level, the dielectric strength of vacuum gap and the opening time. And then the probability of overvoltages when vacuum circuit breakers installed is studied by statistical study in MATLAB.
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Hinterholzer, Thomas. "Der Durchschlag in SF6 unter Einfluss der Raumladungsstabilisierung." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=966110269.
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Brookes, Ricky John. "Exploration of polymer replacements for SF6 in circuit breakers." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526839.
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Harris, Kevin David James. "Realistically evaluating small scale SFD programmes professionalisation and praxis." Thesis, Southampton Solent University, 2016. http://ssudl.solent.ac.uk/3807/.
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Within the last decade a lack of evidence discourse (Nichols et al, 2010) has emerged raising issues around limited Monitoring and Evaluation (M and E) practice and capacity of Sport For Development (SFD) programmes to elicit change. Critics (Coalter, 2013; Harris and Adams, 2016) have argued that a deeper understanding of what works for whom and why (Pawson and Tilley, 1997) is required when evaluating SFD interventions. This thesis explored practitioner involvement in M and E, and drew upon a realist participatory M and E framework (delivered in two phases), developed to train student sport development practitioners (SSDPs) to make sense of how and why their SFD interventions worked. The framework was evaluated at each phase, utilizing Realist Evaluation (RE) to ascertain if, how, and why the framework worked for SSDPs. The evaluation at phase one (involving interviews, blogs, and questionnaires) led to a series of context mechanism and outcome (CMO) configurations explaining how and why the framework worked for SSDPs. This led to refinements of the framework at phase two embedding Schula et al’s (2016) collaborative principles of evaluation. Evaluation of phase two embedded Q factor analysis (Watts and Stenner, 2012), interviews and reflective blogs. Findings emerged surrounding the value of RE for SSDPs. Schula et al’s (2016) principles enabled practical and transformational characteristics to unfold for SSDPs within the framework. Four sub groups of practitioners emerged depicting how the framework worked. These sub groups were made up of ‘travelling far in M and E competency’, ‘polished problem solvers’, ‘passive passengers’, and ‘proficient yet skeptical practitioners’. These were underpinned by holistic narratives demonstrating subjective views about the framework. A new compilation of CMO configurations informing refinements to the framework followed. In conclusion, participatory approaches of M and E can work with practitioners and should be embedded to enable application of RE.
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Petri, Richard. "Etude de l'influence de la température sur les mécanismes de gravure du tungstène et du silicium en plasma SF6 et SF6/O2 dans un réacteur hélicon." Grenoble 1, 1993. http://www.theses.fr/1993GRE10011.
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Des 1987, le tungstene a ete utilise comme metal d'interconnexion dans les filieres 1 m. Le probleme crucial de la gravure de ce materiau est le controle de l'anisotropie (flancs verticaux). Ce parametre est devenu critique pour les filieres 0,7 m. Afin de fournir un procede compatible avec le cahier des charges des filieres 0,5 et 0,35 m (et, nous l'esperons, au-dela), nous avons etudie la gravure du tungstene en plasma sf#6, a basse temperature de surface, de meme que l'utilisation de reacteurs basse-pression, haute densite electronique, et a polarisation independante. Notre travail a consiste d'abord en une caracterisation du plasma utilise, et des surfaces apres gravure. Nous avons recherche une correlation entre ces etudes et les cinetiques de gravure mesurees experimentalement. Nous avons montre que la gravure s'opere par la formation d'une couche reactive en surface, puis par sa destruction (par pulverisation) sous faisceau d'ions. Ces resultats experimentaux, tant que pour le tungstene que pour le silicium, sont en bon accord avec un modele decrivant ces phenomenes. Le role particulier de la temperature a ete mis en evidence dans les mecanismes de gravure: le gel de la desorption spontanee permet d'obtenir une parfaite anisotropie, ce qui, sur un plan technologique, represente un interet considerable
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Duffour, Emmanuel. "Interaction plasma-isolant. Applications au lanceurélectrothermique et à l'interaction SF6-polyéthylène." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2000. http://tel.archives-ouvertes.fr/tel-00011655.
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Ce travail propose une nouvelle approche de la description des phénomènes physiques qui interviennent dans le cadre de la modélisation de l'interaction plasma-isolant. Pour cela un code de calcul de dynamique moléculaire à été réalisé pour décrire les mécanismes fondamentaux qui régissent cette interaction à l'échelle microscopique.Une étude fondamentale de la dynamique moléculaire, basée sur l'utilisation des méthodes numériques particulières comme les intégrateurs symplétiques et l'exploitation des différents potentiels d'interactions existants (Morse, Lennard-Jones...), a abouti à deux modèles de polymère : le polyéthylène ou PE (CH2)n. Le premier modèle dit simplifié consiste à considérer un groupement CH2 comme un atome fictif de masse molaire 14g, tandis que le second plus complet traite la dynamique de l'atome d'hydrogène au sein de la macromolécule. Ces deux modèles sont utilsés, dans le cadre de ce travail, pour diverses interactions.
Par ailleurs, des mesures expérimentales de perte de masse des matériaux polymères qui interagissent avec un plasma, créé par l'explosion d'un fil de cuivre, sont exposées. Ces résultats sont corrélés par des calculs théoriques de thermodynamique qui montrent une différence de comportement des deux polymères testés : le polyéthylène et le polyoxyméthylène, POM ou Delrin (CH2O)n.
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Belhaouari, Jean-Belkheir. "Modélisation de l'extinction d'un arc de SF6 hors d'équilibre thermodynamique local." Phd thesis, Université Paul Sabatier - Toulouse III, 1997. http://tel.archives-ouvertes.fr/tel-00003150.
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Lors de l'extinction d'un arc de disjoncteur, on observe une brutale diminution de la conductance de l'arc, le plasma est alors soumis à un fort soufflage qui peut conduire à des écarts à l'équilibre chimique. Les modèles fondés sur l'hypothèse de l'équilibre thermodynamique local (E.T.L.) prévoient une diminution de la conductance mais ne rendent pas bien compte de l'ensemble des mécanismes régissant l'extinction. La forte convection est responsable de la présence d'une certaine quantité de gaz froid qui n'a pas été totalement dissocié dans les parties chaudes du plasma. Les particules froides peuvent se recombiner rapidement avec les électrons ce qui modifierait la résistivité du milieu. Pour mettre en évidence ce phénomène qui apparaît dans les disjoncteurs nous avons développé un modèle de l'extinction d'un arc de SF6 pour une géométrie simplifiée à deux dimensions. Ce modèle couple un modèle de cinétique chimique avec un modèle hydrodynamique et permet de calculer les densités des espèces. La mise en place de ce modèle s'est caractérisée par des calculs préliminaires pour l'initialisation : la composition du plasma à l'équilibre est obtenue à l'aide d'un modèle collisionnel ; un modèle hydrodynamique à deux dimensions a été développé et nous permet de calculer les champs de température et de vitesses en régime stationnaire. Le modèle a été complété par une étude sur la cinétique du SF6 qui nous a permis de mettre en évidence les différents processus réactionnels qui gouvernent la disparition des électrons. Nous avons simulé l'extinction de l'arc pour une intensité initiale de 50 A et pour des pressions fixées à 0.1 et 0.4 MPa, le modèle cinétique est couplé au modèle hydrodynamique à partir de l'équation des gaz parfaits et de la relation liant la densité de masse aux densités des espèces. Les principaux résultats du modèle hydrodynamique confirment que la vitesse de refroidissement est de l'ordre de -108 K.s-1. Les résultats sur la cinétique montrent que la convection agit sur les molécules de S2 qui se retrouvent, au bord de la décharge et pour des températures comprises entre 4000 K et 6000 K, en surpopulation par rapport à l'équilibre. Par processus d'échange de charge entre les particules S2 et S+ la surpopulation de S2 va conduire à une surpopulation des ions S2+. Ces ions vont principalement se recombiner avec les électrons provoquant une baisse de la population électronique, et une modification de la résistivité du milieu.
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Yoshida, Soh, Hiroki Kojima, Naoki Hayakawa, Fumihiro Endo, and Hitoshi Okubo. "Light Emission Spectrum Depending on Propagation of Partial Discharge in SF6." IEEE, 2008. http://hdl.handle.net/2237/12056.
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Bennis, Mohamed. "Etude expérimentale de la solubilisation de substances organiques dans SF6 supercritique." Paris 13, 1991. http://www.theses.fr/1991PA132002.
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Ce travail est une contribution à l'étude thermodynamique comparative de la solubilisation de quelques composes organiques a fonctions chimiques différentes dans divers solvants supercritiques. Nous avons aborde ici la solubilité dans SF6 supercritique. De manière plus spécifique nous avons étudié l'effet de la taille et du déplacement du groupement hydroxyle OH à l'intérieur de la molécule d'une série d'alcools primaires (C3 à C9OH) sur leur solubilité dans SF6 supercritique. Nous avons également montré l'augmentation de la solubilité d'un soluté dans SF6sc en introduisant des co-solvants appropriés. Sur le plan de modélisation, nous avons représenté les mélanges alcools-SF6 étudiés a l'aide de l'équation d'état de Soave-Redlich-Kwong qui nous a permis de faire une bonne corrélation des compositions dans la phase vapeur avec un écart maximum relatif entre les valeurs expérimentales et calculées acceptables. Les recherches expérimentales futures doivent être axées sur des composés présentant même fonction chimique mais différents par leur taille et leur polarité. Le pouvoir solvant d'autres solvants SC présentant d'autres structures et propriétés physico-chimiques peut également être étudié
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Shimmin, D. W. "High power short circuit studies on an SF6 puffer circuit breaker." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383473.
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Rebzani, Nesrine. "Etude des phénomènes électro-thermiques dans l'appareillage haute tension." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI056/document.
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Après sa production dans des centrales, l'électricité est acheminée sur de longues distances à travers le réseau électrique qui comporte des appareils haute tension destinés à la protection des installations. Parmi ces dispositifs, le GIS (Gaz Insulated Switchgear), dans lequel l'isolation électrique est assurée par le gaz SF6, est très utilisé. Il est soumis à des normes de sécurité imposant, notamment, des seuils de température à ne pas dépasser durant son fonctionnement. La connaissance et la maîtrise des phénomènes électromagnétiques et thermiques à l'origine des augmentations de température dans le GIS sont des enjeux cruciaux. Elles permettent un dimensionnement plus rapide et plus précis des appareils, aboutissant à un unique essai de validation des critères fixés par les normes. Elles fourniront également des solutions visant à réduire les échauffements des GIS. Cette réduction est importante car elle permet la circulation d'un courant plus élevé dans le GIS, ce qui aboutit à une amélioration des performances de l'appareil. Les travaux effectués dans le cadre de cette thèse présentent une analyse des phénomènes électro-thermiques dans le GIS et plus précisément dans les jeux de barres. Ils permettent la détermination des paramètres influençant l'augmentation de température dans cette géométrie. La contribution de chaque mode de transfert de chaleur (convection, rayonnement) est estimée et discutée. Une modélisation numérique du champ de température induite par la circulation du courant dans les jeux de barres est également proposée, en tenant compte du couplage avec le champ de vitesse induitElectricity is produced by power stations and is transported throughout the electric-power transmission at long distances with high voltage apparatus. The GIS (Gas Insulated Switchgear) is widely used switchgear. The electric insulation is ensured by the gas SF6. Security IEC norms impose temperature rises not to be exceeded during GIS operating. It is important to know and control the electromagnetic and thermal phenomenons which generate temperature rises. The switchgear design could then be faster and more precise, leading to only one successful temperature rise test. Solutions to reduce temperatures could also be found. The temperature rise reduction is crucial as it allow a higher current flowing through the GIS and an increase of its efficiency. The word achieved during this thesis presents an analysis of electro-thermal phenomenons in GIS and, more precisely, in busbars. It leads to the determination of the parameters influencing temperature rises and of the heat transfers proportion which is assessed and discussed. A numerical modelization is carried out to examine the temperature rises induced by the current flow in busbars
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Ogiboski, Luciano. "Extensão de ciclo de vida de uma subestação isolada a gás SF6 por meio de um sistema de monitoramento de tempo real." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3143/tde-01082013-161555/.
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Subestações blindadas são utilizadas por empresas de energia há mais de 50 anos. Muitas destas subestações estão em operação até os dias de hoje, sem qualquer modificação em seu projeto original, e ainda assim continuam operando sem apresentar problemas ou indícios de fadiga. Isto pode ser atribuído a sua qualidade construtiva em conjunto com o material isolante utilizado por este tipo de equipamento, o Hexafluoreto de Enxofre (SF6). Este gás possui todas as características desejáveis para manter adequadas as propriedades dielétricas da subestação, além de ser inerte e extremamente estável. O tempo de vida nominal de uma subestação blindada pode ser de 30 a 50 anos, dependendo de suas características ou recomendação do fabricante. A proximidade, ou até a ultrapassagem, do final do tempo de vida gera preocupação às empresas detentoras destes equipamentos antigos no que diz respeito a operação da subestação com segurança. Outro aspecto importante está relacionado a vazamentos de gás na atmosfera, pois o SF6 está entre os elementos mais danosos para o efeito estufa. Por estas razões este trabalho apresenta o desenvolvimento de um sistema para monitoramento de vazamentos e também de parâmetros indicativos do gás SF6 em uma subestação blindada antiga. O objetivo principal foi de desenvolver um sistema com dados históricos para se realizar estudos a respeito do comportamento do gás. A subestação utilizada neste trabalho não possuía nenhum sistema de monitoramento online. Assim, foi desenvolvido um sistema de tempo real para coletar dados de densidade do gás e de ponto de orvalho nos compartimentos da subestação. O sistema de coleta de dados foi instalado em três bays de uma subestação. Foram instalados sensores para medir estas duas grandezas, e também, módulos de aquisição de dados de baixo custo que se comunicam por meio de protocolos padrão e abertos. A partir do sistema instalado, no longo prazo, se espera a redução de vazamentos de gás com a possibilidade de inspeções online. Pode ser atribuído como resultado do trabalho a redução de custos, pois os dados históricos com indicativos favoráveis permitem estender o tempo entre manutenções preventivas. Como resultado complementar deste trabalho, o monitoramento de perdas de gás se torna mais eficiente e rápido, colaborando, assim com as expectativas ambientais atuais.Gas Insulated Substations (GIS) are used by energy companies for over 50 years. Many early substations have been in operation until the present day, without any modification in its original design, and still are operating without problems or indications of fatigue. This can be attributed to its constructive quality along with the insulating material used for this type of equipment, the gas sulfur hexafluoride (SF6). This gas has all the desirable features for maintaining the dielectric of the substation as well as being inert and extremely stable. The nominal lifetime of a GIS substation can be 30 to 50 years, depending on their characteristics or manufacturer\'s recommendation. The proximity, or even exceeding, the lifetime generates concern to companies holding these old equipment as regards the operation of the substation safely. Another important aspect is related to gas leakages into the atmosphere because SF6 is among the most damaging elements to the greenhouse effect. Therefore, this work presents the development of a system for monitoring leakage and also indicative parameters of SF6 gas at an old GIS. The main objective was to develop a system with historical data to conduct studies about the behavior of the gas. The substation used for this work had no online monitoring system. Thus, it was developed a real-time system for collecting data of gas density and dew point in the compartments of the substation. The data collection system was installed in three bays of the substation. Sensors were installed to measure these two quantities, and also low cost data acquisition modules which communicate via standard and open protocols. In long term, with the system, there should be a reduction of gas leakages with the possibility of online inspections of the gas. May be assigned as a result the reduction of costs, since the historical data with good indicative allows extending the time for preventative maintenance. As additional result of this work, it is expected that the monitoring of leakage become more efficient and faster, thus contributing to the current environmental expectations.
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Yamada, T., T. Ishida, N. Hayakawa, and H. Okubo. "Partial discharge and breakdown mechanisms in ultra-dilute SF6 /N2 gas mixtures." IEEE, 2001. http://hdl.handle.net/2237/6754.
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Takahashi, Toshihiro, Tatsuji Yamada, Naoki Hayakawa, and Hitoshi Okubo. "Space charge behavior in SF6 gas and sequential generation of PD pulses." IEEE, 2000. http://hdl.handle.net/2237/6757.
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Tabke, Thorsten [Verfasser]. "Entwicklung und Anwendung eines typunabhängigen, minimalinvasiven Zustandsbewertungsverfahrens für SF6-Hochspannungsschaltanlagen / Thorsten Tabke." Wuppertal : Universitätsbibliothek Wuppertal, 2017. http://d-nb.info/1136873120/34.
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Lüders, Carsten. "Vergleich von Strahlungs- und Turbulenzmodellen zur Modellierung von Lichtbögen in SF6-Selbstblasleistungsschaltern." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=978755030.
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Castellano, Rémy. "Etude de la régulation transcriptionnelle des gènes TNF-SF6 et TNF-SF14." Aix-Marseille 2, 2003. http://www.theses.fr/2003AIX20656.
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Constantin, Florin-Lucian. "Franges de Ramsey à deux photons à très haute résolution de SF6." Paris 13, 2000. http://www.theses.fr/2000PA132028.
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Belkacem, Amrane Abdelkrim. "Défauts induits dans le silicium par la gravure en plasma de SF6." Grenoble 1, 1991. http://www.theses.fr/1991GRE10003.
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Les problemes inherents a la gravure plasma en general et les pmm en particulier, ont ete etudies. Au cours de ce travail, nous avons montre que le profil de dopage des substrats si de type p, perturbe par l'introduction d'hydrogene durant la gravure pouvait etre restaure par un simple traitement thermique a 200c. Nous avons egalement montre par dlts, que quatre niveaux profonds (deux dans si-p et deux dans si-n) etaient systematiquement generes par cette operation. Une analyse detaillee de ces niveaux a montre que deux d'entre eux sont dus a des defauts d'irradiation simples, alors que l'origine des deux autres peut etre attribuee a un defaut complexe associant defaut d'irradiation et contamination par des especes sf#x. Afin de s'en affranchir, nous avons optimise le procede de gravure (determination d'une gamme de polarisation entrainant une gravure s'accompagnant de peu ou pas de defauts). Un traitement thermique approprie permet egalement de reduire sensiblement la concentration des defauts eventuellement presents voire les eliminer totalement. Par ailleurs, une forte contamination metallique a ete observee. Une analyse fine de ce type de pollution a montre qu'elle etait liee a la structure meme des reacteurs utilises et pouvait etre considerablement eliminee sinon reduite par: i) une amelioration de la structure du reacteur; ii) un traitement adequat des parois du reacteur. Dans tous les cas de figure, nous avons clairement demontre qu'un traitement rca effectue apres gravure supprimait toute pollution residuelle (defauts ou contamination metallique). Enfin, nous avons mis en evidence que la gravure perturbe sensiblement la surface du materiau. Ce probleme a ete resolu par l'amelioration du procede de gravure et par l'utilisation d'un nettoyage de surface adequat
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Vianna, Elaine Aparecida de Lima. "Priorização da manutenção em subestações com foco na confiabilidade e na remuneração da função transmissão." Universidade Federal de Santa Maria, 2016. http://repositorio.ufsm.br/handle/1/12913.
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Transmission companies, in Brazilian electricity sector, are paid by the facilities available to the National Interconnected System - SIN. The different equipment on the transmission system are subject to the occurrence of defects, which can result in failure and may result in outages and / or operational constraints. These occurrences cause the application of a penalty, called Variable Portion, consisting of a discount in the amount of remuneration is provided. This thesis aims to support maintenance planning, aiming at the reduction of Variable Portions and of the negative financial impact caused by this penalty, by a new methodology to define a priority scale for maintenance actions in substations, based on the development of a Composite Risk Index (CRI) associated with each device. Two auxiliary indices are built: Basic Condition (BC) and Operating Condition (OC), representing the physical and functional characteristics of the equipment that can compromise their performance and contribute to the occurrence of failures. Their evaluation is helped by a Technical Capacity Index (TCI), which evaluates how much the equipment has been affected by wear and tear, in the assessment of the Basic Condition, and the classification of the equipment defects by degrees of severity, in the assessment of the Operating Condition. Two cascading Fuzzy Inference Systems of the Mandani type are used, the first in defining the BC, and the second to obtain the equipment CRI denoting maintenance priority, which may then be used in planning maintenance actions. The methodology is verified through an SF6 circuit breaker CRI assessment, and its priority scale for maintenance planning. The procedure for evaluating the SF6 circuit breakers reliability is evaluated through a comparison with a statistical approach, using real data collected from equipment installed in Eletrobras Eletronorte Transmission System, in Rondônia, Amazon region of Brazil.As empresas transmissoras de energia, do setor elétrico brasileiro, são remuneradas pelas instalações disponibilizadas para o Sistema Interligado Nacional – SIN. Os diversos equipamentos do sistema de transmissão estão sujeitos à ocorrência de defeitos, os quais podem redundar em falhas e podem resultar em indisponibilidades e/ou restrições operativas. Estas ocorrências provocam a aplicação de uma penalização denominada Parcela Variável, que consiste em um desconto no valor da remuneração. Esta tese visa apoiar o planejamento da manutenção, com o objetivo de reduzir as Parcelas Variáveis e o impacto financeiro negativo, causado por esta penalização, por meio de uma nova metodologia para definir uma escala de prioridade para as ações de manutenções nas subestações, baseada no desenvolvimento de um Índice Composto de Risco (ICR) associado a cada equipamento. São desenvolvidos dois índices auxiliares: Condição Básica (CB) e Condição Operativa (CO), os quais representam as características físicas e funcionais do equipamento, que podem comprometer seu desempenho e contribuir para a ocorrência de falhas. Esta avaliação é realizada com o uso de um Índice de Capacidade Técnica (ICT), que avalia o quanto o equipamento foi afetado pelo desgaste, na avaliação da Condição Básica, e da classificação dos defeitos do equipamento em níveis de severidade, na avaliação da Condição Operativa. Dois Sistemas de Inferência Difusa do tipo Mandani, em um arranjo em cascata, são utilizados, o primeiro na definição da CB, e o segundo para obtenção do ICR que indica a prioridade de manutenção, o qual pode ser utilizado no planejamento das ações de manutenção. Esta metodologia é verificada por meio da avaliação do ICR de Disjuntores a Gás SF6, e sua escala de prioridade para o planejamento de manutenção. O procedimento para avaliação da confiabilidade dos Disjuntores a Gás SF6 é avaliado por meio de uma comparação com uma abordagem estatística, com o uso de dados reais coletados dos registros dos equipamentos instalados no Sistema de Transmissão da Eletrobras Eletronorte, em Rondônia, Região Amazônica do Brasil.
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Dal, Bó Sílvia. "Avaliação da atividade antinociceptiva da subfração 63 (SF63) obtida a partir das cascas da Croton Celtidifolius (Euphorbiaceae)." Florianópolis, SC, 2004. http://repositorio.ufsc.br/xmlui/handle/123456789/87159.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas. Programa de Pós-graduação em Farmacologia.Made available in DSpace on 2012-10-21T15:29:43Z (GMT). No. of bitstreams: 0
A [SF63], obtida das cascas da [Croton Celtidifolius] administrada por via intraperitoneal, provocou antinocicepção quando avaliada nos modelos de contorção abdominal induzida pelo [Ácido acético], no teste da nocicepção induzida pela [Formalina], no teste da [Capsaicina], no teste [Glutamato], no teste da [Retirada da cauda] e no modelo da [Placa quente], em doses que não promoveram reações inespecíficas, como sedação e relaxamento muscular, avaliadas pelo teste do [Rota-rod]. Também foi observado que a [SF63] administrada por via oral apresenta atividade antinociceptiva, quando avaliada no teste da nocicepção induzida pela formalina. Os resultados sugerem que a [SF63]
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Mansour, D. A., H. Kojima, N. Hayakawa, F. Endo, and H. Okubo. "Partial Discharge Characteristics for Small Gap of Electrode/Epoxy Interface in SF6 Gas." IEEE, 2008. http://hdl.handle.net/2237/12127.
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Wember, Martin [Verfasser]. "Untersuchung und Bewertung von TE-belastetem SF6 unter Anwendung der Ionenbeweglichkeitsspektrometrie / Martin Wember." Aachen : Shaker, 2007. http://d-nb.info/1164340190/34.
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Faye, Mbaye. "Signature infrarouge et modélisation pour la télédétection de deux gaz : SF6 et RuO4." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS182.
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Ce travail est une contribution à l'étude spectroscopique de deux gaz d'origine anthropique pour lesquels la modélisation de la signature infrarouge pourra permettre une quantification dans rejets dans l'atmosphère. L'hexafluorure de soufre (SF₆) est principalement rejeté par l'industrie électrique, qui l'utilise comme isolant gazeux et sa concentration augmente rapidement dans l'atmosphère (de l'ordre de 7 % par an). C'est un gaz à effet de serre puissant listé dans le protocole de Kyoto car ses absorptions intenses vers 10 μm placées dans une fenêtre de transparence atmosphérique et sa durée de vie élevée dans la haute atmosphère(environ 3200 ans) lui confèrent un coefficient de transfert radiatif exceptionnellement élevé (Global Warming Potential, ou GWP égal à 23900 fois celui du dioxyde de carbone, CO₂). La détection et la quantification de ce gaz par sa signature infrarouge via des mesures par satellite nécessitent une très bonne modélisation des spectres d'absorption, incomplètement connus. SF6 est un molécule lourde qui présente un grand nombre de niveaux vibrationnels de basse énergie, donnant lieu à des bandes chaudes dans le domaine des absorptions atmosphériques autour de sa vibration fondamentale la plus intense et celles-ci impliquent des états excités peu ou pas caractérisés. Ainsi, à température ambiante, seules 32 %des molécules se trouvent dans l'état vibrationnel de base. Les bases de données actuelles ne contiennent que les données des bandes de vibration fondamentales. Pour pallier ce manque, il est donc nécessaire d'observer un certain nombre de transitions depuis l'état fondamental vers les niveaux excités de basse énergie servant d'état initial aux bandes chaudes et d'acquérir des données permettant de modéliser aussi les niveaux à deux quanta de vibration constituant les niveaux d'arrivée de ces bandes chaudes.Ce travail est une contribution à l'étude spectroscopique de deux gaz d'origine anthropique pour lesquels la modélisation de la signature infrarouge pourra permettre une quantification dans rejets dans l'atmosphère. L'hexafluorure de soufre (SF6) est principalement rejeté par l'industrie électrique, qui l'utilise comme isolant gazeux et sa concentration augmente rapidement dans l'atmosphère (de l'ordre de 7 % par an). C'est un gaz à effet de serre puissant listé dans le protocole de Kyoto car ses absorptions intenses vers 10 μm placées dans une fenêtre de transparence atmosphérique et sa durée de vie élevée dans la haute atmosphère(environ 3200 ans) lui confèrent un coefficient de transfert radiatif exceptionnellement élevé (Global Warming Potential, ou GWP égal à 23900 fois celui du dioxyde de carbone, CO₂). La détection et la quantification de ce gaz par sa signature infrarouge via des mesures par satellite nécessitent une très bonne modélisation des spectres d'absorption, incomplètement connus. SF₆ est un molécule lourde qui présente un grand nombre de niveaux vibrationnels de basse énergie, donnant lieu à des bandes chaudes dans le domaine des absorptions atmosphériques autour de sa vibration fondamentale la plus intense et celles-ci impliquent des états excités peu ou pas caractérisés. Ainsi, à température ambiante, seules 32 %des molécules se trouvent dans l'état vibrationnel de base. Les bases de données actuelles ne contiennent que les données des bandes de vibration fondamentales. Pour pallier ce manque, il est donc nécessaire d'observer un certain nombre de transitions depuis l'état fondamental vers les niveaux excités de basse énergie servant d'état initial aux bandes chaudes et d'acquérir des données permettant de modéliser aussi les niveaux à deux quanta de vibration constituant les niveaux d'arrivée de ces bandes chaudesThis work is a contribution to the spectroscopic study of two gases of anthropogenic origin for which the modeling of the infrared signature may allow a quantification in releases in the atmosphere. Sulfur hexafluoride (SF₆) is mainly rejected by the electrical industry, which uses it as a gaseous insulator and its concentration increases rapidly in the atmosphere (of the order of 7 per cent per year). It is a potent greenhouse gas listed in the Kyoto Protocol because its intense absorption around 10 μm issituated in a window of atmospheric transparency and its lifetime in the upper atmosphere (approximately 3200 years) confers an exceptionally high radiative transfer coefficient (Global WarmingPotential, or GWP equal to 23900 times that of carbon dioxide,CO2). The detection and quantification of this gas by its infrared signature via satellite measurements requires a very accurate modeling of the absorption spectra, incompletely known. For SF₆,in particular because of the fact that this heavy molecule presents a large number of vibrational levels of low energy, there exist hotbands in the region of atmospheric absorption around its most intense fundamental absorption (v₃); these involve excited states little or not characterized. Thus, at ambient temperature, only 32% of the molecules are located in the vibrational ground state. Current databases contain only data for the fundamental vibrationband. To compensate for this lack, it is therefore necessary toobserve a number of transitions from the ground state to the excited levels of low energy used corresponding to initial states of the hot bands and to acquire data for modeling also levels with two quanta of vibration constituting the upper levels of arrival of thes ehot bands.This work is a contribution to the spectroscopic study of two gases of anthropogenic origin for which the modeling of the infrared signature may allow a quantification in releases in the atmosphere.Sulfur hexafluoride (SF₆) is mainly rejected by the electricalindustry, which uses it as a gaseous insulator and its concentration increases rapidly in the atmosphere (of the order of 7 per cent peryear). It is a potent greenhouse gas listed in the Kyoto Protocolbecause its intense absorption around 10 μm is situated in awindow of atmospheric transparency and its lifetime in the upper atmosphere (approximately 3200 years) confers an exceptionally high radiative transfer coefficient (Global Warming Potential, orGWP equal to 23900 times that of carbon dioxide, CO2). The detection and quantification of this gas by its infrared signature via satellite measurements requires a very accurate modeling of theabsorption spectra, incompletely known. For SF6, in particular because of the fact that this heavy molecule presents a largenumber of vibrational levels of low energy, there exist hot bands in the region of atmospheric absorption around its most intensefundamental absorption (v3); these involve excited states little or not characterized. Thus, at ambient temperature, only 32 % of themolecules are located in the vibrational ground state. Current databases contain only data for the fundamental vibration band. Tocompensate for this lack, it is therefore necessary to observe a number of transitions from the ground state to the excited levels oflow energy used corresponding to initial states of the hot bands andto acquire data for modeling also levels with two quanta ofvibration constituting the upper levels of arrival of these hot bands
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Caliap, Lucian. "Etude de l'optimisation des isolants d'un point de vue diélectrique pour les contraintes du GIS." Phd thesis, Université de Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00585494.
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Cette étude concerne les isolants support, utilisés dans l'appareillage haute tension blindé sous pression gazeuse. La réduction de la taille du matériel est une demande constante pour des questions de coût. Elle impacte directement les isolants et l'optimisation diélectrique est rendue nécessaire. On peut considérer que les points qui nécessitent une attention particulière sont : La zone de point triple : point de jonction entre un isolant, le gaz et le métal, zone sensible aux décharges partielles et aux particules qui peuvent s'y accumuler. Les particules métalliques qui peuvent se trouver à l'intérieur du système haute-tension et les problèmes d'accumulation de la charge sur la surface de l'isolant qui peuvent réduire sa tenue diélectrique lors de l'application d'une surtension. Ces trois points représentent la base de départ de cette étude qui caractérise la multitude de phénomènes complexes qui apparaissent en présence de haute tension.
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Vijayaraghavan, Vishnu Karthik. "Methodology to quantify leaks in aerosol sampling system components." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/1195.
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Filter holders and continuous air monitors (CAMs) are used extensively in the nuclear industry. It is important to minimize leakage in these devices and in recognition of this consideration, a limit on leakage for sampling systems is specified in ANSI/HPS N13.1-1999; however the protocol given in the standard is really germane to measurement of significant leakage, e.g., several percent of the sampling flow rate. In the present study, a technique for quantifying leakage was developed and that approach was used to measure the sealing integrity of a CAM and two kinds of filter holders. The methodology involves use of sulfur hexafluoride as a tracer gas with the device being tested operated under dynamic flow conditions. The leak rates in these devices were determined in the pressure range from 2.49 kPa (10 In. H2O) vacuum to 2.49 kPa (10 In. H2O) pressure at a typical flow rate of 56.6 L/min (2 cfm). For the two filter holders, the leak rates were less than 0.007% of the nominal flow rate. The leak rate in the CAM was less than 0.2% of the nominal flow rate. These values are well within the limit prescribed in the ANSI standard, which is 5% of the nominal flow rate. Therefore the limit listed in the ANSI standard should be reconsidered as lower values can be achieved, and the methodology presented herein can be used to quantify lower leakage values in sample collectors and analyzers. A theoretical analysis was also done to determine the nature of flow through the leaks and the amount of flow contribution by the different possible mechanisms of flow through leaks.
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Smith, Jason. "A Sensor Fault Detection Simulation Tool." Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1193282225.
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Mansour, D. A., T. Okusu, K. Nishizawa, H. Kojima, N. Hayakawa, F. Endo, and H. Okubo. "Comparison of Partial Discharge Characteristics for Different Defect Types in SF6 Gas Insulation System." IEEE, 2008. http://hdl.handle.net/2237/12057.
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Qiu, Xiang Qun. "Impulse breakdown characteristics of SF6 and its mixtures in highly non-uniform field gaps." Thesis, University of Strathclyde, 1998. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21398.
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The work reported in this thesis was undertaken in the Centre for Electrical Power Engineering, Department of Electronic and Electrical Engineering, University of Strathclyde to study the impulse breakdown characteristics of SF₆ and its mixtures in highly non-uniform field gaps. Of particular interest were the effects of space charge, artificial irradiation, different gas mixtures, different additive gases and different wave fronts on the impulse breakdown characteristics. High divergent fields can exist in GIS under certain conditions as, for example, when a needle-like free metallic particle is attracted to the inner conductor or is deposited on the surface of an insulator. Such defects can result in very low breakdown levels and, with large defects (e.g. particles several mm long), failure can occur even at the working stress of the equipment. The breakdown characteristics of gases in nonuniform fields, however, are much more complicated than in uniform fields and are not fully understood. This is probably due to the complex effect of space charge on breakdown process [89] and the space charge effect on positive impulse breakdown characteristics of SF6 and its mixtures in highly nonuniform field gaps has become an increasingly important subject on the gaseous dielectrics with high electric strength in high voltage apparatus. The main purpose of the present work is to acquire a better understanding of the corona stabilised breakdown mechanism in SF₆ gas under impulse voltages and to supply a physical base to choose an efficient additive for improving the insulating strength of SF₆ gas. A general introduction is first given, based on a renew of experimental and theoretical work on the subject to date. Descriptions of apparatus and experimental techniques are then given. Two newly developed space charge injection methods, namely corona pin arrangement and direct injection method were used throughout the work. In the case of positive lightning impulse voltage, injected positive space charge has little effect on minimum impulse breakdown, whereas a decrease in breakdown voltage is observed when negative space charges are injected into the gap. Artificial irradiation also decreases the minimum impulse breakdown voltage, though the reduction rate is lower. From these and other observations, it is generally concluded that the major source of initiatory electrons for positive impulse breakdown in an enclosed gap is from the electron detachment from unstable negative Ions and initiatory electrons make an important contribution to the breakdown process. The conclusion is confirmed to a large extent by using a photomultiplier to observe the light emission during the discharge process. The study of the effect of space charges and artificial irradiation shows that although initiatory electrons make an important contribution to the breakdown process, it appears that there is a limit beyond which the breakdown strength cannot be further decreased by increasing the electron or negative-ion population. The study of the addition to SF₆ of 5% R20 or R12 has shown that although space charges have a great effect on impulse breakdown strength in SF₆ there is little, if any, effect on breakdown strength in SF₆/R12 and SF₆/R20 mixtures. The result implies those additives containing chlorine preferentially produce very stable negative ions which do not readily detach. The impulse strength is increased in mixtures containing these additives because there is then a reduced likelihood of successful development of the discharge channel through a scarcity of initiating electrons in the gap. The initiating electrons will be produced mainly by the detachment from negative ions so that the rate of production in the critical volume will itself depend upon the applied waveform [143]. It has been found that the wavetail has little influence on impulse breakdown process [141,158] and only the effect of wavefront is studied. It had been found that the longer the wavefront, the higher the minimum impulse breakdown voltage, the reason is believed to be the sweeping off action which negative ions in the gap are swept out the effectively. Suggestions for further research work are offered in Chapter 9.
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Lüders, Carsten [Verfasser]. "Vergleich von Strahlungs- und Turbulenzmodellen zur Modellierung von Lichtbögen in SF6-Selbstblasleistungsschaltern / Carsten Lüders." Aachen : Shaker, 2005. http://d-nb.info/1186587458/34.
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Lewis, Elfed. "The thermal properties of an SF6 circuit breaker arc during the current zero period." Thesis, University of Liverpool, 1987. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328394.
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High speed photographic and time and space resolved spectroscopic investigations have been undertaken to quantify the processes governing arc thermal reignition phenomena. A fixed nozzle and electrode geometry was used with SF6 as the host gas. A sonic flow of gas at the nozzle throat was sustained using an upstream vessel pressure of 7.8 psig. A 35.5mF capacitor bank was used to supply electrical energy for reduced and full power arcing tests using different circuit configurations. Sophisticated optical diagnostic instrumentation has enabled photographic and spectroscopic investigations with high time and space resolution to be made during the current zero period of both the full and reduced power arcing cases. The results of above experimental investigations are of value in determining the thermal structure and the processes governing thermal reignition of the circuit breaker arc of the present investigation. In particular, temperature profiles derived from the above investigations have been used to quantify the important terms of the dynamic current zero energy balance. Experimental investigations have thus been performed during the critical current zero period of a full power circuit breaker arc. The significance of these results has been realised in evaluating the current zero temperature profiles and subsequently the energy conservation equation terms for severe circuit breaking conditions
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Liu, J. "Modelling and simulation of air and SF6 switching arcs in high voltage circuit breakers." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3003675/.
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This thesis is concerned with the modelling of switching arcs in air in high voltage circuit breakers and with a comparative study of interruption capability of air and SF6 switching arcs. Emphasis is given to the identification of dominant energy transport processes for arc interruption and the material properties associated these processes. There have been renewed interests in air arcs because of its possible use in a mixture with other gases as a replacement for SF6 in circuit breakers for environment protection. Computer simulation of the switching air arc has been carried out using arc models based on laminar flow and on turbulent flow for the experimental set up of Fang et al [41] under DC current and that of Frind and Rich [66] for the current zero period. DC arc voltages predicted by arc model assuming laminar flow (LAM) are much lower than those measured. Thus, turbulence is introduced to account for additional power loss mechanism not included in the laminar flow model. Two turbulence models have been used to take into account of turbulence enhanced momentum and energy transport: the Prandtl mixing length model (PML) and the standard k-epsilon model or its modified version. For the DC air nozzle arc of Fang et al [41] the value of the turbulence parameter, c= 0.06, in PML has been chosen to match the predicted arc voltage with that measured at 1 kA DC and a stagnation pressure of 10 bar. PML can give satisfactory agreement with experiments over a DC current range from 250 A to 3 kA. When the standard k-epsilon model is used, the predict arc voltage is much higher than that measured indicating that turbulence cooling is too strong. One of the turbulence parameters of the standard k-epsilon model which controls the dissipation rate of turbulent kinetic energy is adjusted to match the predicted arc voltage with the experimentally measured arc voltage under the same discharge conditions as those for finding the value of c in PML. With this chosen value of 1 = 1.62, the modified k-epsilon model (MKE) gives similar results to those of PML. Three arc models (LAM, PML and MKE) are used to compute the critical rate of rise of recovery voltage (RRRV) for the air nozzle arc of Frind and Rich [66]. The presence of the shock inside the nozzle in the presence of the arc prevents the optimisation of the value of turbulence parameter for PML due to numerical convergence problems. RRRV predicted by PML and LAM are much lower than the experimental value. MKE with 1 = 1.65 is successful in predicting satisfactorily the RRRV at di/dt= 13.5 A/μs for several stagnation pressures. However, it has been found that a single value of 1 chosen for one value of di/dt cannot give satisfactory prediction of RRRV for other values of di/dt. A comparative computational study of SF6 and air switching arcs based on MKE has been carried out for the experimental conditions of Frind and Rich [66] for di/dt= 13.5A/μs at several stagnation pressures. Under the same discharge conditions RRRV of SF6 switching arc is one order of magnitude higher than that of air switching arc. Such large difference in the interruption capabilities of SF6 and air is due to the different dominant energy transport processes responsible for the arc cooling during current zero period. Two material properties of the arc plasma, the product of density and specific heat at constant pressure (ρCP) and that of density and enthalpy (ρh) are responsible for the distinctive arc features for SF6 and air. SF6 switching arc has a distinctive arc core surrounded by a thin region with steep temperature gradient. Under the same discharge conditions as those of SF6 air switching arc has no distinctive core structure. Its radial temperature profile is very broad and arc radius is much bigger than that of SF6. Such broad radial temperature profile of air arc is due to the peaks of turbulent thermal conductivity at 4,000 K and 7,000 K produced by the corresponding peaks of the material property of ρCP of air. For SF6 ρCP has a peak just below 4,000 K, which ensures rapid temperature decay above 4,000 K and a gentle temperature tail below 4,000 K. In comparison with SF6 under the same pressure difference across the nozzle the velocity inside air arc is much higher than that of SF6. With ρh of air being greater than that of SF6 for temperature higher than 7,000 K together with higher velocity enthalpy transport capability of air arc is much higher than that of SF6. Energy balance calculation for the current carrying core indicates that after the breakdown of quasi-steady state turbulent thermal conduction is the dominant energy transport process for SF6 while for air arc axial convection is dominant. As a consequence the rates of decay of arc temperature and arc radius for air arc a few microseconds before current zero are much slower than those of SF6, thus resulting in a large difference between RRRVs for the two gases under the same discharge conditions. To find an alternative arc quenching gas with similar interruption capability to that of SF6 one should aim at ρCP and ρh of the alternative gas with similar features to those of SF6.
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Paulo, Assis Rogério Gomes da Silva. "Diagnóstico de descargas parciais em subestações isoladas a gás SF6 utilizando redes neurais artificiais." Florianópolis, SC, 2006. http://repositorio.ufsc.br/xmlui/handle/123456789/88736.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia ElétricaMade available in DSpace on 2012-10-22T12:59:12Z (GMT). No. of bitstreams: 1 234339.pdf: 1611971 bytes, checksum: 2a048bf5b3b720f9e4b9b21fd3ae4c61 (MD5)
O presente trabalho de dissertação aborda o desenvolvimento de uma ferramenta computacional para o diagnóstico de Descargas Parciais (DP) que ocorrem em Subestações Isoladas à Gás (GIS), em especial ao gás hexafluoreto de enxofre (SF6). Esta ferramenta computacional é baseada nas Redes Neurais Artificiais (RNA), com arquitetura do tipo Multi-Camadas (MLP). O objetivo da ferramenta é fornecer a causa para a ocorrência da Descarga Parcial que é capturada pelo sistema de monitoramento através da emissão de altíssimas freqüências (UHF), dando suporte ao operador para melhores procedimentos em relação à GIS. Para a validação da ferramenta foram utilizados dados gerados a partir do catálogo do sistema de monitoramento instalado na SE Machadinho, pertencente à ELETROSUL. Esse diagnóstico é de grande valia para a manutenção preditiva de uma GIS, pois indica a atividade da DP que dependendo da intensidade e das características destas descargas degradam as características de isolação elétrica do gás SF6. Assim, a equipe de manutenção responsável pela GIS, com a utilização das informações deste diagnóstico, pode atuar de forma mais eficaz nesta subestação. This master#s thesis research results in the development of a computational tool for Partial Discharge (PD) diagnosis taking place at Gas Insulated Substation (GIS), especially with sulphur hexafluoride (SF6). This computational tool is based on an Artificial Neural Network (ANN), with a Multi-Layer Perceptron (MLP) architecture. The target of this tool is to give the cause of occurrence of Partial Discharge captured by system monitoring through emission of ultra high frequency (UHF) signals, giving support to the operator for better procedures about GIS. The tool is validated with data generated from the catalog of a monitoring system installed at Machadinho Substation, owned by the Transmission Company of Electric Energy ELETROSUL. This diagnostic is of great value for GIS preventive maintenance because of given PD activity. Depending on the discharge intensity and characteristic it can destroy the electric isolation of the SF6 gas. With this diagnostic, the responsible maintenance team can work more effectively at this substation.
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Robert, Thomas. "Etude d'un arc de disjoncteur à SF6 : modèle physique et intéraction avec le circuit." Toulouse 3, 1992. http://www.theses.fr/1992TOU30021.
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Cette these porte sur l'etude d'un arc de disjoncteur a hexafluorure de soufre (sf#6) capable d'interrompre des courants alternatifs de 25 ka dans des reseaux de distribution de l'electricite a tres haute tension (20 kv). Les parties les plus importantes de ce travail consistent a simuler le comportement de l'arc au moyen d'un modele physique lors du passage au zero du courant et durant la phase post-arc et a coupler cette simulation a un modele de circuit pour evaluer l'interaction de l'arc avec le reseau. Ces travaux sont associes a des experimentations qui permettent de valider le modele se rapportant a un disjoncteur a double soufflage. Le traitement de deux phenomenes a ete particulierement etudie: la turbulence et les pertes radiatives. Pour la turbulence on a developpe un modele de longueur de melange que l'on a adapte aux proprietes particulieres de l'arc de disjoncteur. L'etude bibliographique de valeurs experimentales de temperature et des modelisations simplifiees d'arc, ont permis de montrer que les valeurs du coefficient d'emission nette du sf#6 habituellement utilisees sont sous-estimees. Durant la phase post-arc, le soufflage turbulent induit un refroidissement important qui conduit a une transition tres rapide entre un etat conducteur du milieu et un etat dielectrique. Lorsque la tension transitoire apparait, elle induit le courant post-arc qui produit un echauffement par effet joule. Si cet echauffement est superieur aux pertes d'energie, il se cree un emballement thermique et un echec de coupure. Les calculs montrent que l'influence de l'arc est ressentie par la ttr et par consequence sur le courant post-arc. Une procedure iterative entre notre modele physique et le modele de circuit (dans lequel l'arc intervient comme une resistance tres rapidement variable) permet de montrer que l'arc attenue la pente de la tension transitoire initiale et modifie assez sensiblement le courant post-arc
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Belmadani, Bachir. "Etude de la décomposition de l'hexafluorure de soufre (SF6) dans un arc de puissance." Toulouse 3, 1989. http://www.theses.fr/1989TOU30173.
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Cette etude porte sur la decomposition de l'hexafluorure de soufre (sf#6) sous l'effet d'arcs de puissance. Ces contraintes ont ete generees dans deux types de disjoncteurs: 1-auto-soufflage; 2-auto-pneumatique fp-62. Les produits de decomposition gazeux formes au cours des essais ont ete analyses et doses par chromatographie en phase gazeuse. Les principaux gaz de decomposition identifies ont ete: le sof#2, le so#2,le so#2f#2, et puisque l'arc atteint un isolant organique (buses en teflon ou en pps ryton), le cf#4. Les evolutions des taux de ces produits ont ete etudiees en fonction d'un grand nombre de parametres: energie dissipee, courant d'arc, forme de l'onde de courant, taux d'humidite du sf#6, nature des materiaux constituant les buses, forme de ces buses, presence d'un adsorbant. . . Parallelement, une etude de la diffusion du cf#4 dans un disjoncteur 145 kv alsthom rempli de sf#6 (p#s#f#6=120; 300; 400 kpa) a ete effectuee
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Wang, Weizong. "Investigation of the dynamic characteristics and decaying behaviour of SF6 Arcs in switching applications." Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/12033/.
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Investigation into the dynamic characteristics and decaying behaviour of SF6 arcs during the current-zero period is of great significance to improving the interruption performance of high voltage circuit breakers and ensuring their reliable operation. The present research was conducted by means of modeling and experiment to provide a better knowledge of the switching process to help the design and optimization of high voltage SF6 circuit breakers. The first part of the work concerns the determination of thermophysical properties of SF6 plasmas under local thermodynamic equilibrium state (LTE). A systematic comparison with transport coefficients obtained using an old data set and experimental test has been performed to check the reliability of the proposed phenomenological approach in evaluating transport cross sections. Properties especially transport coefficients become sensitive to the choice of Debye length definition predominantly due to the different collision integrals affected by the different screening distance. Pressures increase can also influence thermophysical properties due to the inhibited chemical reactions. Moreover, the thermophysical properties under non-equilibrium conditions have been investigated using a two-temperature model. It was noted that the special case with equal electrons and heavy species temperatures produces results agreeing excellently with those obtained by the LTE model. The forms of mass action laws as well as the choice of reaction excitation temperature for molecular ionization used in the calculation can significantly modify the species composition and plasma properties. This model lays the micro-theoretical foundation for a deeper understanding of SF6 plasma formation and evolution mechanism and provides a reliable properties input for non-equilibrium arc behaviour simulation. Following a traditional approach of arc modelling assuming LTE, considerable effort has been devoted to study the arc-shock interaction and its influence on the dynamic characteristics and current zero behaviour of SF6 arcs in a supersonic nozzle with a hollow contact. It was found that the close coupling between the shock region and its surrounding gas flow greatly influences the aerodynamic and electrical behaviour of a nozzle arc and hence the thermal recovery process. In addition, deceleration of gas flow caused by the shocks and enhanced turbulent cooling brought by the sucked gas interacting with the arc both play a significant role in the determination of the thermal interruption capability. Possible departure from LTE in a decaying SF6 arc was studied using a two-temperature hydrodynamic model in a supersonic nozzle under well-controlled conditions. The predicted radial temperature variation presents quite good agreement with test result using emission spectroscopy. It is demonstrated that the electron and heavy-particle temperature diverge in cases where the collision energy exchange is ineffective. For the arc decay phase, the two-temperature model gives a lower cooling rate than the LTE model, and hence a higher conductance of the discharge passage at current zero showing the necessity of using a two-temperature model to accurately predict the current interruption capability of SF6 gas-blast circuit breakers. For thermal recovery phase, considering the chemically non-equilibrium effect, a global kinetic model of decaying SF6 arcs was established to study the electrons elimination mechanisms around current zero. For dielectric recovery phase, the critical dielectric strength of hot SF6 are investigated based on a two-term Boltzmann equation solution of electrons energy distribution function. It is noted that the main mechanisms of electrons elimination are the dissociative attachment from 3500K to 7500K, electron-molecular ion recombination in the temperature lower than 3500K. The temperature increase, pressure decrease and departure from chemically non-equilibrium can all contribute to the dielectric strength reduction. The entrainment of PTFE ablation vapour can enhance the dielectric strengh of SF6 above 2500K. Finally, this research manufactures a model SF6 gas blast interrupter and investigates the dynamic characteristics of electrical, light radiation, pressure along together with electrode movement. Arc dynamic characteristics and decaying behaviour of CO2 and N2 is compared with that of SF6 arcs in order to obtain the dominant properties influencing arc quenching. It is noted that the extinction voltage, which decreases with increase in the interrupting current, is related to the conductance decay during current zero period and can be considered as an evaluation of interruption capability. Gas blast can bring a much more rapid variation of arc resistance and a much higher cut-off current before its extinction. SF6 has a superior interruption capability possibly due to its high thermal conductivity and specific heat.
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Flores, Ramírez Alejandro Tomás. "Reemplazo de Subestaciones Convencionales Aisladas en Aire por Tecnología Gis (SF6). Análisis Técnico - Económico." Tesis, Universidad de Chile, 2010. http://www.repositorio.uchile.cl/handle/2250/103759.
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Ingeniero Civil ElectricistaEl propósito de esta memoria es analizar los aspectos más relevantes relacionados con el reemplazo de subestaciones convencionales con aislamiento en aire por subestaciones con aislamiento en gas hexafluoruro de azufre (SF6). Se analizan distintas alternativas de equipamiento y esquema de suministro para los diferentes tipos de subestaciones, para las configuraciones de aislamiento en aire y aislamiento en SF6. En términos generales, la selección del reemplazo de una subestación convencional por una subestación con aislamiento en gas SF6, responde a las ventajas comparativas relacionadas con un mejor aprovechamiento del espacio, menor intervención al equipamiento debido a mantenimiento, flexibilidad en la operación, mayores niveles de confiabilidad, estandarización a máxima altitud de operación, menor accidentalidad y mayor disponibilidad del terreno, entre otros. En la actualidad, se observa una masificación en el uso de subestaciones con aislamiento en gas SF6, principalmente por la fuerte reducción en los costos de fabricación debido a su producción en serie. Con ello, están desplazando en los estudios de factibilidad a las subestaciones tradicionales con aislamiento en aire, particularmente en instalaciones de alta tensión (220 kV) ubicadas sobre los 1000 m.s.n.m., incidiendo en la toma de decisiones de las grandes empresas de minería y en las empresas de transmisión de energía eléctrica. Se realizaron las valorizaciones de los presupuestos para cada solución (GIS y AIS) en su vida útil, resultando interesante la utilización de equipamiento GIS para las subestaciones de alta tensión tanto en S/E O’Higgins como las Estaciones de Bombeo Nº 2, 3 y 4, principalmente debido a la estandarización de este tipo de equipamiento en las subestaciones eléctricas involucradas en el proyecto, las cuales se ubican hasta 2.400 m.s.n.m.. A esta valorización se debe adicionar como elemento de toma de decisión en la selección del equipamiento, el incremento en la robustez de operación y el mínimo mantenimiento que éstas tienen, reduciendo la necesidad de personal de operaciones y mantenimiento para este objeto, otorgando una gran flexibilidad operacional.
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Duluard, Corinne. "Etude de nouvelles voies de passivation non polymérisante pour la gravure profonde du silicium." Phd thesis, Université d'Orléans, 2009. http://tel.archives-ouvertes.fr/tel-00413276.
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La gravure plasma de structures à fort rapport d'aspect dans le silicium est une étape clé dans la fabrication de microsystèmes et de composants de microélectronique de puissance. L'objectif de ce travail est de développer un procédé de gravure profonde du silicium, qui fonctionne à plus haute température de substrat que le procédé cryogénique en chimie plasma SF6/O2 et qui présente une meilleure stabilité en température et en concentration de gaz passivant(s). Dans ce but, de nouvelles voies de passivation non polymérisante ont été explorées. Nous avons évalué les possibilités de passivation par l'apport de SO2 en remplacement de O2. A température cryogénique, les propriétés de gravure sont semblables en plasma SF6/SO2 et SF6/O2 ; elles sont corrélées aux densités de neutres mesurées par spectrométrie de masse et actinométrie. La majeure partie des recherches a été consacrée à l'étude de la molécule SiCl4 comme précurseur de passivation. Nous avons au préalable analysé les interactions entre espèces générées en plasma SF6/SiCl4. Les expériences de caractérisation du plasma montrent que les réactions aux parois entre atomes F et espèces SiClx contrôlent la chimie du plasma et donc les propriétés de gravure du silicium. En mélange SF6/O2/SiCl4, ces réactions influent également sur la vitesse de gravure du substrat, mais l'ajout de SiCl4 à SF6/O2 a surtout pour effet de favoriser l'attaque chimique latérale. Nous avons finalement étudié la possibilité de former une couche de passivation par plasma SiCl4/O2 à température de substrat de -20 °C. Les résultats de cette étude permettent de proposer un nouveau procédé, basé sur l'alternance d'étapes de gravure par plasma SF6 et d'étapes de passivation par plasma SiCl4/O2.
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Borge, Egil. "Modélisation de la cinétique chimique d'un plasma d'arc d'hexafluorure de soufre (SF6) en présence d'impuretés." Toulouse 3, 1995. http://www.theses.fr/1995TOU30184.
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La these a pour but la modelisation de la cinetique chimique du sf#6 dans un arc de disjoncteur en extinction en presence d'impuretes qui peuvent etre de trois sortes: l'eau, le carbone (ou le cf#4) et le cuivre. Ce travail repose sur la resolution d'un systeme d'equations differentielles couplees correspondant aux equations de conservation des differentes especes chimiques, mettant en jeu les diverses voies de creation et de disparition de ces especes par le biais de toutes les reactions chimiques les liant entre elles. Le modele est constitue en tout de 61 especes chimiques reliees entre elles par 230 reactions chimiques. Afin de valider les resultats obtenus par le modele cinetique, nous avons realise une serie d'experiences dont les mesures ont pour but de quantifier les proportions des especes gazeuses contenues dans le milieu, apres le refroidissement de l'arc. Nous avons d'abord calcule les compositions d'equilibre de divers melanges constitues chacun de sf#6 et d'une certaine concentation variable en impuretes. L'etude de ces compositions a permis la connaissance des temps de relaxation des differentes especes, grandeurs qui permettent d'estimer a priori si des ecarts a l'equilibre chimique du milieu apparaissent. Nous avons ensuite calcule les compositions des divers milieux envisages durant l'extinction du plasma. Nous avons pu faire varier la decroissance de la temperature et la pression. Le resultat le plus remarquable obtenu par le code numerique est le comportement des especes sof#2 et so#2f#2 durant l'extinction de l'arc. Les densites de ces deux especes ont une evolution tres differente de celle prevue par la composition d'equilibre. Cette evolution a ete confirmee lors des essais experimentaux. Le sof#2 est majoritaire devant le so#2f#2 en dessous de 1 000 k et se transforme en so#2 a la temperature ambiante de 300 k avec une constante de temps qui depasse le mois. Une espece tres importante est la molecule s#2f#1#0 puisqu'elle est tres toxique. D'apres nos calculs, la production de s#2f#1#0 dans ces dispositifs reste tres faible et l'etude experimentale a montre que la proportion de cette molecule est inferieure au seuil de detection du systeme utilise qui se situe a 1 ppmv
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Lagarde, Frédérique. "Décomposition de l'hexafluorure de soufre (SF6) sous l'effet de décharges couronne influence du matériau d'électrode." Toulouse 3, 1992. http://www.theses.fr/1992TOU30032.
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Cette etude concerne la decomposition de l'hexafluorure de soufre (sf#6) soumis a des decharges couronne generees entre un point et un plan. Les principaux produits de decomposition gazeux formes sont alors le so#2f#2, le sof#2 et le s#2f#1#0. Ils ont ete analyses et doses par chromatographie en phase gazeuse. La stabilite au cours du temps a temperature ambiante, di sof#2 et du s#2f#1#0 a fait l'objet d'une etude particuliere. La production de ces trois composes a ete etudiee pour deux materiaux constituant l'electrode plane: l'acier inoxydable et l'aluminium. L'etude de l'evolution de ces produits en fonctions de la charge transportee q (0 a 9c environ) a ete realisee, pour chaque materiau d'electrode, suivant plusieurs parametres; type de tension (ac 50 hz, dc polarite negative), intensite du courant de decharge (12
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Sette, Chaman. "Contribution a l'etude du phenomene de claquage de l'hexafluorure de soufre (sf6) sous haute pression." Toulouse 3, 1987. http://www.theses.fr/1987TOU30163.
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Etude du comportement dielectrique du sf6 aux differents etats gazeux, liquide et hypercritique dans le domaine de haute pression. En premier lieu et dans le cadre de ce memoire, on a mis au point un dispositif experimental de haute pression pouvant travailler jusqu'a 100 bars avec des temperatures de -50 a +200 c et des tensions maximales de 70 kv en alternatif ; en second lieu, on procede a des mesures systematiques de la tension de claquage en champ uniforme (plan-plan) et non uniforme (pointe-plan) dans les gammes de pression de 1 a 67 bars, de temperature de -30 a +60 c avec des densites de 6 a 1445 kg/m3
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Randrianandraina, Hery Zo. "Améliorations des méthodes de calcul du transfert radiatif dans des plasmas thermiques : application au SF6." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1331/.
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"A cause de sa forte dépendance géométrique et spectrale, la prise en compte du rayonnement et du transfert radiatif dans les modèles se fait à travers des méthodes approchées. Pour valider leur utilisation et apporter d'éventuelles améliorations, nous confrontons ces méthodes à un calcul " exact ". Dans ce travail, nous décrivons finement le spectre d'un plasma de SF6 avec près de 300000 points en fréquence (ou longueur d'onde). A partir de ce découpage, nous avons calculé la divergence du flux radiatif soit à partir de la méthode approchée du coefficient d'émission nette (CEN) basée sur une simplification géométrique du plasma, soit à partir de coefficients moyens d'absorption (CMA) obtenus après découpage du spectre en 7 intervalles spectraux pour lesquels le rayonnement est supposé invariant avec la fréquence dans chacun d'entre eux, soit à partir d'un calcul " exact " correspondant à la résolution directe de l'équation du transfert radiatif. Nous avons également calculé le flux radiatif à partir des deux dernières méthodes, le coefficient d'émission nette ne permettant pas le calcul de cette grandeur. Les différentes étapes de calcul y sont présentées mettant en évidence l'influence de certains paramètres comme le nombre de points utilisés pour discrétiser le spectre, l'erreur commise lors de l'utilisation du facteur de fuite revenant à négliger le chevauchement des raies, les largeurs des raies à considérer pour le calcul des profils correspondant, le nombre de directions à prendre en compte dans le calcul de la divergence du flux radiatif. . . Pour la détermination des coefficients moyens d'absorption, plusieurs moyennes ont été testées: moyenne de Planck, moyenne de Rosseland et moyenne classique. Les calculs ont été réalisés pour des configurations simples (1D, 2D et 3D) simulant un plasma cylindrique dont la température ne varie qu'en fonction du rayon. Une grande partie de ce travail porte sur la comparaison des résultats obtenus par le calcul " exact " avec ceux déduits des différentes approchées dans le but de valider leur utilisation ainsi que leur précision. L'analyse des résultats obtenus nous amène à définir de nouveaux intervalles spectraux et de nouvelles moyennes comme par exemple la combinaison de la moyenne de Planck et de la moyenne classique. Cette étude a été effectuée pour unplasma de SF6 utilisé dans les disjoncteurs à haute tension, mais pourrait être généralisée pour tout plasma thermique à condition que l'équilibre thermodynamique local soit réalisé. "Because of a strong spectral and geometric dependence, the consideration of the radiation and the radiative transfer in the numerical models is done through approximate methods. To validate their use and to bring any improvement, we have compared these methods with the "exact" calculation. In this work, we have carried out a detailed description of the spectrum of SF6 plasmas with about 300000 points on frequency. From this description, we have calculated the divergence of the radiative flux either from the net emission coefficient (NEC) based on a geometric simplification of the plasma, or from the mean absorption coefficients (MAC) calculated after a division of the spectrum into 7 intervals in which we have assumed a constant radiation for each of them, or from an exact calculation corresponding to a direct solution of the radiative transfer equation. We have also calculated the radiative flux from the two last methods since the net emission coefficient is not adapted to estimate this property. The different steps of the work are presented and highlight the influence of several parameters such as the number of points used to discretize the spectrum, the discrepancies observed when we use the escape factor to estimate the emission or the absorption of the lines, the influence of the lines overlapping, the integration of the lines' profiles, the number of directions to consider in order to estimate correctly the divergence of the radiative flux. . . For the mean absorption coefficients, three definitions have been tested : the Planck mean, the Rosseland mean and the classical mean. All calculations have been done for simplified configurations (1D, 2D and 3D) assuming a cylindrical plasma for which the temperature profile varies only with the radius. A great part of this work deals with the comparison between the results obtained from the exact resolution with the results deduced from the other approaches in order to validate the use and the accuracy of the different methods. The results' analysis leads us to redefine new spectral intervals and new mean functions as the combination of the Planck mean and the classical mean. This study have been performed for SF6 plasmas used in high voltage circuit breakers but it could equally be generalized for any thermal plasma in local thermodynamic equilibrium
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Okubo, Hitoshi, Diaa-Eldin A. Mansour, Hiroki Kojima, Naoki Hayakawa, and Fumihiro Endo. "Influence of accumulated surface charges on partial discharge activity at micro gap delamination in epoxy GIS spacer." IEEE, 2009. http://hdl.handle.net/2237/13942.
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Diaz, Joseph. "Etude de la décomposition de l'héxafluorure de souffre (SF6) et de mélanges héxafluorure de soufre-azote contenant 5% ou 10% de SF6 soumis en présence de divers additifs, à des décharges couronne ou à des claquages." Toulouse 3, 2002. http://www.theses.fr/2002TOU30047.
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Le présent travail porte sur l'étude de la composition chimique de mélanges SF6-N2 contenant 5% ou 10% de SF6 après qu'ils aient été soumis à des décharges couronne continues de polarité négative ou alternatives 50Hz réalisées en géométrie pointe-plan (P=400kPa) ou à des claquages générés à partir de la décharge d'un condensateur (P=100kPa; énergie dissipée par claquage: 3,59J) en l'absence ou en présence de divers additifs: eau et/ou dioxygène dans le cas des décharges couronne, H2O, O2, méthane (CH4), éthane (C2H4), octofluoropropane (C3F8), oxyde de carbone (CO), dioxyde de carbone (CO2) ou encore isolants solides organiques comme le polyéthylène [CH2]n, le polypropylène [C3H6]n ou le Téflon [C2F4]n dans celui des claquages. La composition chimique des mélanges est ensuite comparée à celle du SF6 non-dilué soumis, à la même pression, aux mêmes types de contraintes, en l'absence ou en présence des mêmes additifs. .The present work deals with the chemical composition of SF6-N2 mixtures containing 5% or 10% of SF6 after being submitted, with a point-plane geometry, to dc negative or 50Hz ac corona discharges (P=400kPa) or sparks generated by discharging a capacitor (P=100kPa; 3. 59J per spark). It was studied in the presence or absence of different additives : H2O and/or O2 for corona discharges and H2O, O2, methane (CH4), ethane (C2H4), octofluoropropane (C3F8), carbon monoxide (CO), carbon dioxide (CO2) or even solid organic insulators like polyethylene [CH2]n, polypropylene [C3H6]n or Teflon [C2F4]n for sparks. The chemical composition of the mixtures was then compared to those of undiluted SF6 submitted to the same types of stress, at the same pressure, in the presence or absence of the same additives. .