Este artigo apresenta um estudo detalhado sobre o dimensionamento de relés Buchholz para transformadores de potência com isolamento a óleo. São abordados os princípios de funcionamento, os critérios de seleção, a instalação e os procedimentos de testes e manutenção. O objetivo é fornecer uma orientação prática e rigorosa que contribua para a segurança e fiabilidade dos sistemas de proteção.
Este documento fornece uma metodologia completa para o dimensionamento de Descarregadores de Sobretensões (DSTs) em redes de Média Tensão (MT), Alta Tensão (AT) e Muito Alta Tensão (MAT).Abordam-se as normas aplicáveis (portuguesas, europeias, internacionais e E-Redes), critérios técnicos, seleção de fabricantes e um estudo de caso prático. O objetivo é capacitar o leitor a dimensionar DSTs com elevado profissi...
Este trabalho apresenta uma análise detalhada do comportamento de motores trifásicos com enrolamentos em configuração triângulo (Δ) sob diferentes condições de defeito. São estudados dois cenários específicos: a saída de serviço de um enrolamento do motor e a abertura de uma das linhas de alimentação (perda da fase B). Desenvolvemos o estudo comparando o regime equilibrado normal com os regimes desequilibrados ...
Este trabalho apresenta uma análise detalhada do comportamento de motores trifásicos com enrolamentos em configuração triângulo (Δ) sob diferentes condições de defeito. São estudados dois cenários específicos: a saída de serviço de um enrolamento do motor e a abertura de uma das linhas de alimentação (perda da fase B). Desenvolvemos o estudo comparando o regime equilibrado normal com os regimes desequilibrados ...
Introduction: The INF1-QoL questionnaire is an essential tool for assessing patients’ perceptions of their illness and its impact on their daily lives. This study aimed to obtain and validate the European Portuguese version of this questionnaire. Methods: The English version of INF1-QoL was translated using the “forward-backward” procedure. The questionnaire was administered to 78 adult patients with neurofibro...
Blind people have been, over time, a reason for motivation in the development of solutions to improve their quality of life. The aim of this work is to propose a solution for one of such problems, namely, the selection and combination of clothing for the blind. Thus, this paper describes the whole project developed, in agreement with the Portuguese Association of the Blind and Amblyopic of Portugal (ACAPO), for...
The electricity sector has been subjected to major changes in the last few years. Previously, there existed a regulated system where electric companies could know beforehand the amount of energy each generator would produce, hence basing their largely operational strategy on cost minimization in order to increase their profits. In Spain, from 1988 till 1997, electricity prices were established by the ‘Marco Leg...
This paper aims to study distribution network topology optimization considering uncertain load and distributed generation. Gradual increase of distributed generation in distribution network leads the network operator companies to concern more about having the best network topology, so their costs can be the lowest. MATLABTM genetic algorithms function is used to model this mathematical problem in its basic defi...
This paper studies the impact of the energy upon electricity markets using Multidimensional Scaling (MDS). Data from major energy and electricity markets is considered. Several maps produced by MDS are presented and discussed revealing that this method is useful for understanding the correlation between them. Furthermore, the results help electricity markets agents hedging against Market Clearing Price (MCP) vo...
Forecasting electricity prices is a fundamental task for all type of markets participants including electricity markets. There are factors that bring unce1tainty to price formation, such as demand forecasting, fuel prices, player's strategies, regulatory changes, weather conditions and technical restrictions and generation availability. In addition, the particular characteristics of electricity (supply must be ...