In this master thesis the new possibilities of software Autodesk Inventor Professional 2008 are described. Autodesk Inventor is a system for 3D machine engineering containing tools for 3D modeling, information management, cooperation and technical support. Autodesk Inventor Professional 2008 has a lot of new possibilities and improvements compared to the previous version. This Master thesis contains also description of the circuit breaker BD250N and its utilization in the distribution of low voltage. In enclosed CD the model animation of circuit breaker with description of modeling process can be found. The Autodesk Inventor Professional 2008 is used for this master’s thesis – English version.

The heat generated in a circuit breaker can be transmitted in two ways: Either through metal parts of current path to conductors outside of device or through plastic parts or air of chassis. The accuracy of the simulation depends on the accuracy of the 3D model and all his parts and it also depends on precise definition of materials with precise definition of electrical and thermal parameters. Electrical circuit breaker has various source of the heat which results in raising temperature of the device above the level of environment. Heat sources are: 1) Joule’s loss of the circuit breaker current path. 2) Heat loss in a bimetal, which is used for thermal release. 3) Resistivity of contacts. This thesis deals with static state of thermal analysis so the sources do not include transient heat source for switching OFF and switching ON. Electrical circuit breakers are made in smaller and smaller forms however their electrical parameters are not decreasing with size. There is logical conclusion that there is more heat on the same unit size which makes thermal analysis of circuit breaker one of the most important part of development.

Master of Science / Department of Electrical and Computer Engineering / Medhat M. Morcos / The inclusion of Selective Coordination in the NEC since the 2002 revision and the expansion of applications for which coordination of Over-current Protective Devices is required have resulted changes in design approaches for electrical engineers. In order to meet the requirements of the NEC regarding Selective Coordination for secondary power systems within buildings, often, upstream protective devices need to be held-in to a short-circuit condition, thus increasing the Arc Flash Energy. Electrical engineers must understand the many aspects of Selective Coordination when approaching a project from the very beginning. Decisions made by the engineer regarding Selective Coordination will have influence on project cost, project timeline, robustness of the electrical equipment, and safety of personnel working near or on the electrical equipment. The main objectives of this report are to convey an understanding of the following: recent changes in requirements for Selective Coordination, implications of short-circuit analysis, impacts of selectively coordinated systems on Arc Flash Energy, risks surrounding Arc Flash Hazards, and design processes regarding Selective Coordination.

Introdução: O arco dentário superior de pacientes com mordida cruzada posterior normalmente apresenta-se atrésico e a expansão rápida da maxila é indicada para esses casos durante a dentadura mista promovendo abertura da sutura palatina mediana e incrementos transversais na região posterior do arco dentário. Objetivo: O objetivo deste trabalho consistiu em avaliar os efeitos da expansão rápida da maxila, utilizando o disjuntor com cobertura em acrílico, por meio do acompanhamento clínico e radiográfico. Material e Método: A amostra do estudo foi composta por 21 pacientes com mordida cruzada posterior, uni ou bilaterais e atresia do arco dentário superior. O procedimento de expansão rápida da maxila foi realizado na dentadura mista tardia, por meio do aparelho de expansão com cobertura oclusal em acrílico. Foram realizados exames de feixe cônico antes da instalação do aparelho e 06 meses após a instalação do disjuntor McNamara, na ocasião da remoção do aparelho. Nas imagens de tomografia computadorizada, as mensurações foram realizadas por meio do software On Demand 3D (Versão 1.0, Cybermed Inc., Seul, Coreia do Sul). Nas imagens de tomografia computadorizada foram analisadas a espessura das tábuas ósseas vestibular e lingual, o nível da crista óssea vestibular dos primeiros molares permanentes, a largura do palato duro, a distância transversa entre os primeiros molares superiores. Os parâmetros clínicos foram obtidos mensalmente até o final do tratamento: o índice de placa dental visível (IPV), índice sangramento gengival (ISG), profundidade de sondagem (PS), nível clínico de inserção (NIC) e índice de sangramento à sondagem (SS). As medidas pré e pós-tratamento foram submetidas ao teste t pareado (p<0,05). Resultados: Não foram observadas diferenças estatisticamente significantes entre o tempo inicial e final para as variáveis IPV, ISG, ISS, PS E NIC, porém houve um aumento significativo para PS e NIC durante os períodos de 30, 60 e 150 dias. Os resultados das medidas realizadas por meio da TCFC não mostraram diferenças estatisticamente significantes entre os tempos para a altura da crista óssea vestibular. A espessura da tábua óssea vestibular diminuiu nos molares permanentes e deciduos, sendo essa diminuição significativa apenas nos molares permanentes (p<0,05), enquanto que no lado palatino aumentou significativamente (p<0,001) em todos os dentes analisados. Não houve redução da crista óssea vestibular. À distância bi-molar mostrou um aumento significativo (p<0,001) tanto na região cervical quanto na região apical. O mesmo aumento significativo (p<0,001) foi verificado para a largura do palato. Conclusão: Os resultados dos parâmetros clínicos e das medidas realizadas por meio da tomografia computadorizada permitiu constatar o efeito ortopédico do disjuntor com acrílico na oclusal dos dentes na expansão rápida da maxila. As alterações observadas não sugerem danos significativos aos dentes e nas estruturas periodontais avaliadas. / Introduction: The upper dental arch of patients with posterior crossbite is usually atresic and rapid maxillary expansion is indicated for these cases during the mixed dentition, promoting the opening of the medial palatine suture and transverse increments in the posterior region of the dental arch. Objective: The purpose of this study was to evaluate the effects of rapid maxillary expansion using the acrylic cover breaker, through clinical and radiographic monitoring. Material and Method: The study sample consisted of 21 patients with posterior crossbite, uni or bilateral and upper dental arch atresia. The rapid maxillary expansion procedure was performed in the late mixed dentition using the expansion apparatus with acrylic occlusal cover. Cone beam tests were performed prior to appliance installation and 06 months after the McNamara circuit breaker was installed at the time of removal. Computed tomography images were measured using On Demand 3D software (Version 1.0, Cybermed Inc., Seoul, South Korea). Computed tomography images were analyzed for the thickness of the buccal and lingual bone plates, the level of the buccal bone crest of the first permanent molars, the width of the hard palate, the transverse distance between the first maxillary first molars. Clinical parameters were obtained monthly until the end of the treatment: visible dental plaque index (IPV), gingival bleeding index (ISG), probing depth (PS), clinical insertion level (NIC) and bleeding probing index SS). Pre- and posttreatment measurements were submitted to paired t-test (p <0.05). Results: There were no statistically significant differences between the initial and final time for IPV, ISG, ISS, PS and NIC, but there was a significant increase for PS and CIN during the 30, 60 and 150 day periods. The results of the measurements made through the CBCT did not show statistically significant differences between the times for the height of the buccal bone crest. The thickness of the buccal bone plate decreased in the permanent and deciduous molars, which was only significant in the permanent molars (p <0.05), whereas on the palatine side it increased significantly (p <0.001) in all teeth analyzed. There was no reduction of the buccal bone crest. At the bi-molar distance showed a significant increase (p <0.001) in both the cervical region and the apical region. The same significant increase (p <0.001) was found for the width of the palate. Conclusion: The results of the clinical parameters and the measurements made by means of the computerized tomography allowed to verify the orthopedic effect of the acrylic breaker in the occlusal of the teeth in the rapid expansion of the maxilla. The observed changes do not suggest significant damage to the teeth and to the periodontal structures evaluated.

A vacuum interrupter is a switching device used in vacuum circuit breakers, which are widely employed in medium voltage circuits for interrupting the short-circuit fault currents. The vacuum interrupter is the chamber in which the arc extinction and hence the current interruption takes place. On the occurrence of a fault, the breaker mechanism separates the contacts of the vacuum interrupter. As the contacts separate, an arc is established between the contacts. The arc evolves in the contact space and extinguishes at or near the current zero, thus interrupting the current. The processes of arc ignition, evolution and extinction are very complex. These processes are fundamental to the design and the performance of the vacuum interrupter and hence the circuit breaker. The evolution of the arc predominantly depends on the short-circuit current, the design and metallurgy of the contacts. The evolution of the vacuum arc has been the focal point of considerable research activity. Significant effort has been concentrated to understand the various modes of the arc, the transition between the modes, the arc movement and the dependency on the contact design and finally the effect of the arc evolution on the current interruption performance of the vacuum interrupter. The voltage across the contacts during the arcing, termed as the arc voltage, has been a focal point of several research projects. Research has shown that the arc voltage depends strongly on the mode and the evolution process of the arc. The dependency is observed with respect to the magnitude and the nature of the arc voltage. This dependency has been established through the comparison of the arc voltage trace and the actual arc photographs. The arc voltage is thus an important parameter in understanding the arcing process in the interrupter. Arc voltage could also be utilised to compare the arcing behaviour in vacuum interrupters with different contact geometries and metallurgies. Having understood how the arc voltage depends on the arc modes and how it can be used to analyse the arcing performance of the interrupter, this work aims to establish experimentally the dependency of the arc voltage on fundamental parameters of the short-circuit current and the contact design. The variation of the arc voltage is studied with respect to the magnitude of the short-circuit current. It is seen that the magnitude of the arc voltage is higher, for a higher short-circuit current. This dependency is also reflected in the nature of the arc voltage waveform. The effect of cumulative short- circuit operations has been understood through the study of arc voltage variation with respect to the accumulated arcing time. It has been found that the arc voltage consistently decreases as the accumulated arcing time increases. The effect of the contact diameter on the arc evolution has been studied by comparing the arc voltage variations for contacts of different diameters for the same short-circuit current. It is observed that the variation of arc voltage with respect to the contact diameter depends on the type of contact. In the case of radial magnetic field contacts, it has been observed that the arc voltage is lower for a contact with lower diameter. Whereas in the case of axial magnetic field contacts there is an inverse relation between the contact diameter and the arc voltage. Finally, the effect of the type and distribution of the magnetic field on the arc voltage variation as well as the contact erosion has been studied. In general, the observations show that the arc voltage magnitude for the radial magnetic field geometry is higher than the axial magnetic field geometry. Also, there is a significant difference in the appearance of the arc voltage waveforms for the arcs under the two types of magnetic fields. Finite element simulations and short-circuit evaluations have shown that the axial magnetic field contact system with 90 deg coil orientations yield a more uniform distribution of the flux density and hence lower erosion of the contacts. These results show a clear dependence of the arc voltage on the various above mentioned parameters. Thus the arc voltage could be utilised as a diagnostic parameter during the evaluation of the vacuum interrupter. In the present scenario, significant research is being done to increase the breaking capacity of the interrupters. This calls for optimization of design of the existing contacts and the design of novel contact geometries. The arc voltage would be used as an important diagnostic tool in this process. Also, the utilization of vacuum interrupter in high voltage and extra high voltage circuits is being explored. This application requires increase in the contact gap or series connection of gaps. The arc behaviour in longer gaps and gaps connected in series would be an important research area. Again the arc voltage could be used to study the arc evolution in these specialised conditions. The experiments in this research work have been performed on commercial vacuum interrupters. For a dedicated research on vacuum arcs and vacuum interrupter contacts, development of a vacuum arc research facility has also been attempted as a part of this research work.

Introdução: O arco dentário superior de pacientes com mordida cruzada posterior normalmente apresenta-se atrésico e a expansão rápida da maxila é indicada para esses casos durante a dentadura mista promovendo abertura da sutura palatina mediana e incrementos transversais na região posterior do arco dentário. Objetivo: O objetivo deste trabalho consistiu em avaliar os efeitos da expansão rápida da maxila, utilizando o disjuntor com cobertura em acrílico, por meio do acompanhamento clínico e radiográfico. Material e Método: A amostra do estudo foi composta por 21 pacientes com mordida cruzada posterior, uni ou bilaterais e atresia do arco dentário superior. O procedimento de expansão rápida da maxila foi realizado na dentadura mista tardia, por meio do aparelho de expansão com cobertura oclusal em acrílico. Foram realizados exames de feixe cônico antes da instalação do aparelho e 06 meses após a instalação do disjuntor McNamara, na ocasião da remoção do aparelho. Nas imagens de tomografia computadorizada, as mensurações foram realizadas por meio do software On Demand 3D (Versão 1.0, Cybermed Inc., Seul, Coreia do Sul). Nas imagens de tomografia computadorizada foram analisadas a espessura das tábuas ósseas vestibular e lingual, o nível da crista óssea vestibular dos primeiros molares permanentes, a largura do palato duro, a distância transversa entre os primeiros molares superiores. Os parâmetros clínicos foram obtidos mensalmente até o final do tratamento: o índice de placa dental visível (IPV), índice sangramento gengival (ISG), profundidade de sondagem (PS), nível clínico de inserção (NIC) e índice de sangramento à sondagem (SS). As medidas pré e pós-tratamento foram submetidas ao teste t pareado (p<0,05). Resultados: Não foram observadas diferenças estatisticamente significantes entre o tempo inicial e final para as variáveis IPV, ISG, ISS, PS E NIC, porém houve um aumento significativo para PS e NIC durante os períodos de 30, 60 e 150 dias. Os resultados das medidas realizadas por meio da TCFC não mostraram diferenças estatisticamente significantes entre os tempos para a altura da crista óssea vestibular. A espessura da tábua óssea vestibular diminuiu nos molares permanentes e deciduos, sendo essa diminuição significativa apenas nos molares permanentes (p<0,05), enquanto que no lado palatino aumentou significativamente (p<0,001) em todos os dentes analisados. Não houve redução da crista óssea vestibular. À distância bi-molar mostrou um aumento significativo (p<0,001) tanto na região cervical quanto na região apical. O mesmo aumento significativo (p<0,001) foi verificado para a largura do palato. Conclusão: Os resultados dos parâmetros clínicos e das medidas realizadas por meio da tomografia computadorizada permitiu constatar o efeito ortopédico do disjuntor com acrílico na oclusal dos dentes na expansão rápida da maxila. As alterações observadas não sugerem danos significativos aos dentes e nas estruturas periodontais avaliadas. / Introduction: The upper dental arch of patients with posterior crossbite is usually atresic and rapid maxillary expansion is indicated for these cases during the mixed dentition, promoting the opening of the medial palatine suture and transverse increments in the posterior region of the dental arch. Objective: The purpose of this study was to evaluate the effects of rapid maxillary expansion using the acrylic cover breaker, through clinical and radiographic monitoring. Material and Method: The study sample consisted of 21 patients with posterior crossbite, uni or bilateral and upper dental arch atresia. The rapid maxillary expansion procedure was performed in the late mixed dentition using the expansion apparatus with acrylic occlusal cover. Cone beam tests were performed prior to appliance installation and 06 months after the McNamara circuit breaker was installed at the time of removal. Computed tomography images were measured using On Demand 3D software (Version 1.0, Cybermed Inc., Seoul, South Korea). Computed tomography images were analyzed for the thickness of the buccal and lingual bone plates, the level of the buccal bone crest of the first permanent molars, the width of the hard palate, the transverse distance between the first maxillary first molars. Clinical parameters were obtained monthly until the end of the treatment: visible dental plaque index (IPV), gingival bleeding index (ISG), probing depth (PS), clinical insertion level (NIC) and bleeding probing index SS). Pre- and posttreatment measurements were submitted to paired t-test (p <0.05). Results: There were no statistically significant differences between the initial and final time for IPV, ISG, ISS, PS and NIC, but there was a significant increase for PS and CIN during the 30, 60 and 150 day periods. The results of the measurements made through the CBCT did not show statistically significant differences between the times for the height of the buccal bone crest. The thickness of the buccal bone plate decreased in the permanent and deciduous molars, which was only significant in the permanent molars (p <0.05), whereas on the palatine side it increased significantly (p <0.001) in all teeth analyzed. There was no reduction of the buccal bone crest. At the bi-molar distance showed a significant increase (p <0.001) in both the cervical region and the apical region. The same significant increase (p <0.001) was found for the width of the palate. Conclusion: The results of the clinical parameters and the measurements made by means of the computerized tomography allowed to verify the orthopedic effect of the acrylic breaker in the occlusal of the teeth in the rapid expansion of the maxilla. The observed changes do not suggest significant damage to the teeth and to the periodontal structures evaluated.

Monitoring of abnormal events in a distribution feeder by using a single technique is a challenging task. Many abnormal events can cause unsafe operation, including a high impedance fault (HIF) caused by a downed conductor touch ground surface, an incipient fault (IF) caused by partial breakdown to a cable insulation, and a circuit breaker (CB) malfunction due to capacitor bank de-energization to cause current restrikes. These abnormal events are not detectable by conventional protection schemes. In this dissertation, a new technique to identify distribution feeder events is proposed based on the complex Morlet wavelet (CMW) and on a decision tree (DT) classifier. First, the event is detected using CMW. Subsequently, a DT using event signatures classifies the event as normal operation, continuous and non-continuous arcing events (C.A.E. and N.C.A.E.). Additional information from the supervisory control and data acquisition (SCADA) can be used to precisely identify the event. The proposed method is meticulously tested on the IEEE 13- and IEEE 34-bus systems and has shown to correctly classify those events. Furthermore, the proposed method is capable of detecting very high impedance incipient faults (IFs) and CB restrikes at the substation level with relatively short detection time. The proposed method uses only current measurements at a low sampling rate of 1440 Hz yielding an improvement of existing methods that require much higher sampling rates.

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.

In this master’s thesis there is firstly conducted research about pressure measurement. Next there is mathematical description of thermodynamic conditions in used testing chamber by using magnetohydrodynamic and Maxwell equations. Next chapter deals with testing chamber itself, more precisely with function, model and changes done to it. In practical part there are data measured by used sensors, which are also closer described in this chapter. In next chapter there is comparison of reaction times of used sensors and their frequency specters, obtaining using fast Fourier transformation. Second to last chapter introduces very measurement on the real device and in the last chapter these data are analyzed and more closely described.

This thesis deals with study of durability of low voltage switching devices components. It describes components of circuit breaker and low voltage contactor and contains function models of these devices in various states. Based on model analysis, components that can get worn, damaged or destroyed were selected. Further practical experiments on two samples of circuit breakers from different manufacturers were executed to verify their technical parameters and parts durability. Failure of some components can cause switching device to malfunction.