Proteção de sistemas eletricos industriais: relés e suas aplicações em subestações

Electrical installations in industries involving high currents and voltages considered. On the other side is the common appearance of electrical failures, caused by human error, defects in electrical equipment or electrical installation aging itself. These failures are varied, those with the highest rate of occurrence and cause much damage to electrical installations, are overcurrent and overvoltage. Therefore there is a need to project a system that can detect and minimize possible effects caused by faults in electrical installations industries. Protection systems in electric industries emerge as an alternative to control especially voltage and current magnitudes. Engineered based on the functions of the relays, protection systems are an indispensable tool for any industrial substation. But the project of such systems becomes increasingly more complex, due to technological development. Electrical equipment not develop at the same speed that the protective devices (relays), making it indispensable knowledge of integration of technologies

Proteção Diferencial de Transformadores Usando a Transformada Wavelet

Pós-graduação em Engenharia Elétrica - FEIS

Proteção de motores elétricos de grande porte

Large electric motors require greater care when driving, especially during continuous operation since they are part of day-to-day manufacturing sector, acting essentially to ensure that no damage occurs to the production process and equipment that are part of the same system. This work includes the analysis of electrical protection in a system comprised of a three phase induction motor driven by a frequency converter as well as an analysis of the functions of a multifunction electronic relay. It is presented a comparison between the existing functions in a converter and a relay and a real case is described in order to exemplify the use of an electric motor and features that are aimed at their protection, and the system in which it is inserted. Based on the results, it is of great importance in this field of performance studies, generating relevant results, which may be exposed in order to unify into a single document, different sources of information that are arranged randomly, improve utilization motor and extend the life of equipment forming part of the electrical installation

Estudo e analise dos sistemas de proteção em subestações automatizadas de energia elétrica

Electrical energy is present in the lives of all people and is extremely important that it be delivered to end users with plenty of quality, safety and low costs. The electric power substations are responsible for transmission and distribution of electricity generating sources to consumers, and with technological advances and the subsequent automation of same, the electricity began to be delivered with greater continuity and reliability. Protection systems in substations are largely responsible for making the electricity reaches the final consumer with quality, since their function is to prevent the spread of any type of failure occurred at any point of transmission to the load centers. These systems consist primarily by the current transformers and potential, by the protective relays and circuit breakers and switchgear. The processors send the necessary data to the relays and, if those detect any abnormality in the system, operate the opening command of the branch circuit breakers to isolate where the fault. Therefore, it is essential to better understand the operation of such equipment, as well as the overall system. This work aims to study the main substation equipment, current transformers and potential and, especially, protection relays, in order to obtain the advantages that automated systems can provide

Incêndio - um risco constante com elevado potencial de perigo

Desde a idade média, quando ardiam cidades inteiras, a humanidade tem aprendido muito e tem desenvolvido constantes esforços para evitar e circunscrever os incêndios. Estes esforços, no entanto, foram compensados pelo surgir de outras fontes de ignição e da crescente cargas combustíveis. Hoje, praticamente todos os lares e empresas possuem computadores, televisores, lâmpadas halogenas, máquinas de café e outros aparelhos eletricos, bem como equipamentos de aquecimento e de ar condicionado, etc. A maioria destes dispositivos incluem uma unidade de alimentação e outros módulos electrónicos, constituindo, assim, potenciais fontes de ignição. Mas os incêndios também podem ser estabelecidos de forma intencional. A percentagem de incêndios de origem criminosa já e de 25 a 40%, e os valores estão a aumentar [1]. Os incêndios provocados intencionalmente propagam-se frequentemente muito mais rapidamente tornando o seu combate extremamente difícil. Em media, esses tipo de incêndios são três vezes mais dispendiosos que a media das ocorrências dos incêndio[2].

Protección en sistemas eléctricos de potencia

Tesis (Maestro en Ciencias de la Ingeniería Eléctrica con Especialidad en Potencia) UANL, 1997.

Aplicación de redes de neuronas artificiales a la protección de distancia

Tesis (Maestro en Ciencias de la Ingeniería Eléctrica con especialidad en Potencia) UANL, 1998

Éclatement et contraction lagrangiens et applications

Soit (M, ω) une variété symplectique. Nous construisons une version de l’éclatement et de la contraction symplectique, que nous définissons relative à une sous-variété lagrangienne L ⊂ M. En outre, si M admet une involution anti-symplectique ϕ, et que nous éclatons une configuration suffisament symmetrique des plongements de boules, nous démontrons qu’il existe aussi une involution anti-symplectique sur l’éclatement ~M. Nous dérivons ensuite une condition homologique pour les surfaces lagrangiennes réeles L = Fix(ϕ), qui détermine quand la topologie de L change losqu’on contracte une courbe exceptionnelle C dans M. Finalement, on utilise ces constructions afin d’étudier le packing relatif dans (ℂP²,ℝP²).

Síntese e caracterização de ferrita ni-zn pelo método dos precursores poliméricos calcinada por energia de microondas

Magnetic ceramics have been widely investigated, especially with respect to intrinsic and extrinsic characteristics of these materials. Among the magnetic ceramic materials of technological interest, there are the ferrites. On the other hand, the thermal treatment of ceramic materials by microwave energy has offered various advantages such as: optimization of production processes, high heat control, low consumption of time and energy among others. In this work were synthesized powders of Ni-Zn ferrite with compositions Ni1- xZnxFe2O4 (0.25 ≤ x ≤ 0.75 mols) by the polymeric precursor route in two heat treatment conditions, conventional oven and microwave energy at 500, 650, 800 and 950°C and its structural, and morphological imaging. The materials were characterized by thermal analysis (TG/ DSC), X-ray diffraction (XRD), absorption spectroscopy in the infrared (FTIR), scanning electron microscopy (SEM), X-ray spectroscopy and energy dispersive (EDS) and vibrating sample magnetometry (VSM). The results of X-ray diffraction confirmed the formation of ferrite with spinel-type cubic structure. The extrinsic characteristics of the powders obtained by microwave calcination and influence significantly the magnetic behavior of ferrites, showing particles ferrimagnéticas characterized as soft magnetic materials (soft), is of great technological interest. The results obtained led the potential application of microwave energy for calcining powders of Ni-Zn ferrite

A escola de ensino médio público noturno: uma conjuntura favorável ao protagonismo estudantil coletivo em contraposição ao protagonismo juvenil via empoderamento

Ce travail etude le protagonisme juvénile en école de enseignement sécondaire publique, avec emphase a l enseignement nocturne. Considere las médiations que determinent le paradigme du protagonisme juvénile defendu pour théoriciens pos modernes et documents de reforme de enseignement sécondaire brésilien. Montre que les explications sur le protagonisme juvénile font part d une conception de pouvoir juvenile, proposé pour organismes multilatérales avec la volonté de mobiliser les jeunes pauvres pour faire actions du combat a pauvreté dans les nations sur le point de développement, conjoncture auquel sont proposées théories et pratiques que viabilizent la subsistance des jeunes pauvres en situation de risque. Discute la question de pouvoir juvenile et indique que la proposition de le protagonisme juvénile via pouvoir ont une espace favorable dans le sphère du enseignement sécondaire, niveau de la plupart de jeunes. Montre que la défense de pouvoir juvenile occulte chances de actions étudiants collectifs que permetent une intervention sociopolitique au élève de enseignement sécondaire, qui ont selement une function de homologation. Propose une recherche de possibilités de incentifs a le protagonisme juvénile collectif ou protagonisme étudiant collectif, auquel le étudiant presente suggestions pour le planification et éxecution de activités didactique pédagogiques dans l`école publique de enseignement sécondaire. Defend que la gestion démocratique, avec emphase en procès participatif, c est la principal déterminacion pour le protagonisme étudiant collectif. Méthodiquement , considere las dimensions suivantes pour le protagonisme juvénile: a) configuration de protagonisme juvénile b) protagonisme juvénile dans perspective légal/institutionel ; c) enseignement sécondaire et protagonisme juvénile ; d) possibilité de construction de protagonisme étudiant collectif dans enseignement sécondaire nocturne en Rio Grande do Norte, état choisi pour recherche. Sistematize une technique de revision de litérature sur le thème et informations d une consultation de documents, au-delà de donné constants de Banc de donées de la recherche Le Enseignement Sécondaire Publique Nocturne :registre et analyse de expérience dans l état de Rio Grande do Norte. Conclusion : il faut contribuer pour débats sur la participation politique de les jeunes dans le enseignement sécondaire nocturne, en presentant possibilités reéles de protagonisme étudiant collectif ; opinions presentées pour élèves sont très importantes a une direction d un rôle académique fait pour institutions scolaires dans ce moment , parce que des étudiants sont correspondants a interlocuteurs privilégiés ; le élève peut et deut être consulté depuis le moment de élaboration jusqu a réalisation de activités scolaires ; bien que il y a des entraves et difficultés immanents au enseignement sécondaire publique nocturne, se forment noveaux espaces de démocratisation de idées

EIT: Escalonador Inteligente de Transações

In order to guarantee database consistency, a database system should synchronize operations of concurrent transactions. The database component responsible for such synchronization is the scheduler. A scheduler synchronizes operations belonging to different transactions by means of concurrency control protocols. Concurrency control protocols may present different behaviors: in general, a scheduler behavior can be classified as aggressive or conservative. This paper presents the Intelligent Transaction Scheduler (ITS), which has the ability to synchronize the execution of concurrent transactions in an adaptive manner. This scheduler adapts its behavior (aggressive or conservative), according to the characteristics of the computing environment in which it is inserted, using an expert system based on fuzzy logic. The ITS can implement different correctness criteria, such as conventional (syntactic) serializability and semantic serializability. In order to evaluate the performance of the ITS in relation to others schedulers with exclusively aggressive or conservative behavior, it was applied in a dynamic environment, such as a Mobile Database Community (MDBC). An MDBC simulator was developed and many sets of tests were run. The experimentation results, presented herein, prove the efficiency of the ITS in synchronizing transactions in a dynamic environment

Especificação e implementação de um modelo assíncrono para replicação, propagação e conciliação de bases de dados distribuídas

This graduate thesis proposes a model to asynchronously replicate heterogeneous databases. This model singularly combines -in a systematic way and in a single project -different concepts, techniques and paradigms related to the areas of database replication and management of heterogeneous databases. One of the main advantages of the replication is to allow applications to continue to process information, during time intervals when they are off the network and to trigger the database synchronization, as soon as the network connection is reestablished. Therefore, the model introduces a communication and update protocol that takes in consideration the environment of asynchronous characteristics used. As part of the work, a tool was developed in Java language, based on the model s premises in order to process, test, simulate and validate the proposed model