Electrical Transformers
Mostrando 13-24 de 29 artigos, teses e dissertações.
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13. Falhas e defeitos ocorridos em transformadores de potência do sistema elétrico da Celg, nos últimos 28 anos: um estudo de caso / Faults and damage occurring in power transformers Celg electrical system in the last 28 years: a case study
Os transformadores, além de serem fundamentais para o sistema elétrico de potência, eles também representam uma parte significativa dos investimentos pertencentes à implantação desse sistema. Dessa forma, o acompanhamento e a monitoração das suas condições operativas, de seu sistema isolante, e das condições de funcionamento de seus acessórios
Publicado em: 2008
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14. Feeders parallelism through vis-a-vis disconnecting switches in aerial primary distribution network. / Paralelismo de alimentadores através de seccionadoras de vis-à-vis na rede aérea primária de distribuição.
An important aspect related to the distribution systems operation concerns the safety required in the post-disturbances restorement actions or in the emergency and scheduled maneuvers, which involve the need for load transfer between primary overhead feeders of a same sub-station or for an adjacent sub-station, in a safe and reliable way, complying with the
Publicado em: 2008
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15. Destinação final de transformadores elétricos contaminados com PCBs, via tecnologia de descontaminação e reciclagem dos metais: um ganho ambiental, econômico e da saúde ocupacional / Final destination of PCBs contaminated electrical transformers, through a technology of decontamination and metallic components recycling: a gain for the environment, for the occupational health and finance
The electrical transformers contains Polychlorinated Biphenyls (PCBs), at the end of their lifespan and or by legal imposing, must have theirs disposal in environmentally appropriate conditions. This thesis will be based upon the authors previous research and study, which resulted in an industrial unit named TECORI, located in Pindamonhangaba, SP. It has bee
Publicado em: 2007
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16. Voltage unbalace numerical evaluation and minimization:estimation by incremental sensitivity analysis and analytical solutions / Avaliação e minimização numérica do desequilíbrio de tensão : estimativa por análise de sensibilidade incremental e soluções analíticas
Voltage unbalance is one of the parameters analysed in power quality studies, representing the difference between the magnitudes of the voltages of a tri-phase electrical system, and the phase shift between these. It is desirable to have sinusoidal voltages with identical magnitudes and 120 electrical degrees phase shift between them, but in practice, there
Publicado em: 2007
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17. Frequency estimation in power system through adaptive filtering / Estimação da freqüência em sistemas elétricos de potência através de filtragem adaptativa
This work presents a method for frequency estimation in power systems using adaptive filters based in the algorithm of least mean square (LMS). The analysis of the power system is made through the conversion of the three-phase voltages in a complex signal with the application of alfabetatransform, whose complex form was directed to the algorithm of adaptive
Publicado em: 2007
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18. Modelo de monitoramento e avaliação da confiabilidade e disponibilidade de sistemas de distribuição de energia elétrica com base nas condições de uso de transformadores. / A monitoring and evaluation model of the reliability and availability of electric power distribution systems based on transformers usage conditions.
This work presents and proposes a model to supervise and evaluate an electrical energy distribution system by applying the usage conditions based maintenance technique on the power and distribution transformers. Monitoring the distribution system transformers with the usage conditions technique allows the system administrator to perform a preventive maintena
Publicado em: 2006
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19. Caracterização de harmônicos causados por equipamentos eletro-eletrônicos residenciais e comerciais no sistema de distribuição de energia elétrica
The non linearity on the profile of residential and commercial electrical loads has been growing, mainly in these days of seeking for bigger energy efficiency of household appliances as well as the access of the population to electronic consumer goods. The preocupation for a better power quality has been growing by the customer and also by the energy distrib
Publicado em: 2006
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20. Nanocrystalline material in toroidal cores for current transformer: analytical study and computational simulations
Based on electrical and magnetic properties, such as saturation magnetization, initial permeability, and coercivity, in this work are presented some considerations about the possibilities of applications of nanocrystalline alloys in toroidal cores for current transformers. It is discussed how the magnetic characteristics of the core material affect the perfo
Materials Research. Publicado em: 2005-12
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21. Estudo de potência reativa, tensão, contingência e perdas em empresas de energia elétrica localizadas na Grande São Paulo
In the middle of the 20 20th th century the Brazilian electrical energy sector experienced a rapid growth, since that occasion the problem of voltage control in the transmission and distribution systems grabbed the attention of energy authorities, electrical sector offices and high voltage consumers. With the limitation of reactive power in transmission line
Publicado em: 2005
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22. A method based on fuzzy logic for selection of contingencies in electrical energy transmission systems / Um metodo baseado em logica nebulosa para classificação de contingencias em redes de energia eletrica
This work is intended to discuss the use of performance index in steady state contingency analysis considering overload in transmission lines and transformers. The second order performance index is the most used due to the lowest computational effort, on the other hand, the use of this index results in a miss classification, called masking effect. In order t
Publicado em: 2005
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23. THE COST OF MAINTENANCE TRANSFER UNDER LOAD TAP OF THE TRANSFORMERS POWER OF EXTRA HIGH VOLTAGE THE ELETRONORTE / METODOLOGIA PARA REDUÇÃO DE CUSTOS NA MANUTENÇÃO DOS COMUTADORES DE TAP SOB CARGA DOS TRANSFORMADORES DE POTÊNCIA DE EXTRA ALTA TENSÃO DA ELETRONORTE
In this work a methodology for reduction of maintenance cost in the on-load tap changers (OLTC) of extra high voltage is proposed. The methodology is based on the use of Artificial Neural Networks (ANN) for the intelligent processing of input signals of the commutator. The neural nets adequately trained allow to create an information system and dedicated dia
Publicado em: 2005
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24. ESTIMATED DAILY INTAKE OF POLYCHLORINATED BIPHENYLS FROM CHEESE BY UNIVERSITY STUDENTS IN SANTA MARIA RS BRASIL / INGESTÃO DIÁRIA ESTIMADA DE BIFENILOS POLICLORADOS A PARTIR DE QUEIJO POR UNIVERSITÁRIOS EM SANTA MARIA RS
Foodstuffs free of toxic substances are a continuous concern, for food industry, educational and research institutes, and mainly for consumers. Polychlorinated biphenyls (PCBs) are industrial organochlorine substances used in electrical transformers and capacitors oil. Due to the inappropriate discharge, PCBs contaminate the environment and enter in the food
Publicado em: 2005