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O presente relatório apresenta o trabalho desenvolvido durante o estágio presencial na empresa Alferpac - Projectos, Assistência e Obras Públicas, S.A., na Benedita, no âmbito da conclusão do Mestrado em Engenharia Eletrotécnica - Energia e Automação, na Escola Superior de Tecnologia e Gestão do Instituto Politécnico de Leiria.
O estágio centrou-se em duas vertentes principais: a execução de atividades de projeto de sistemas elétricos (levantamentos em obra, dimensionamento de quadros elétricos, traçado de caminhos de cabos, projetos de iluminação, cálculos de correntes e dimensionamento de cabos e respetivas proteções, ventilação de postos de transformação e aumentos de potência) e o desenvolvimento de um estudo sobre o problema das indutâncias mútuas quando são utilizados cabos monocondutores em sistemas trifásicos.
O estudo analisou comparativamente oito configurações de condutores trifásicos em paralelo (cabos monocondutores), distribuídas por quatro geometrias principais (retangular, estratificada, horizontal e triangular), com o objetivo de minimizar correntes de circulação e perdas por efeito Joule. A metodologia baseou-se no desenvolvimento de um modelo computacional em Excel, fundamentado no artigo científico de S.-Y. Lee, que calcula indutâncias mútuas e quantifica o desempenho através do fator de perdas (δ𝑡).
Os resultados revelaram uma hierarquia clara de desempenho: o arranjo retangular espelhado (Cenário 1-A) destacou-se como solução ótima (δ𝑡=1,00055), enquanto a disposição estratificada permutada (Cenário 2-B) registou o pior desempenho (δ𝑡=1,03264). Verificou-se ainda que a eficácia da permutação de fases depende fortemente da geometria: em arranjos compactos, a simetria estrutural é preferível; na geometria horizontal, o espelhamento revela-se vantajoso. Estes resultados constituem uma ferramenta prática para a seleção de configurações que minimizem perdas energéticas e promovam uma operação mais sustentável.
The present report documents the work developed during the on-site internship at the company Alferpac - Projectos, Assistência e Obras Públicas, S.A., in Benedita, within the scope of the conclusion of the Master’s in Electrical Engineering - Energy and Automation, at the School of Technology and Management of the Polytechnic Institute of Leiria. The internship focused on two main fronts: the execution of electrical systems project activities (site surveys, sizing of electrical panels, cable path routing, lighting projects, current calculations and sizing of cables and respective protections, ventilation of transformer stations and power increases) and the development of a study about the problem of mutual inductances when single-core cables are used in three-phase systems. The study analyzed comparatively eight configurations of three-phase conductors in parallel (single-core cables), distributed by four main geometries (rectangular, stratified, horizontal and triangular), with the objective of minimizing circulation currents and Joule effect losses. The methodology was based on the development of a computational model in Excel, based on the scientific article by S.-Y. Lee, which calculates mutual inductances and quantifies the performance through the loss factor (δ𝑡). The results revealed a clear performance hierarchy: the mirrored rectangular arrangement (Scenario 1-A) stood out as the optimal solution (δ𝑡 = 1.00055), while the permuted stratified layout (Scenario 2-B) recorded the worst performance (δ𝑡= 1.03264). It was also found that the effectiveness of phase permutation is strongly dependent on the geometry: in compact arrangements, structural symmetry is preferable; in the horizontal geometry, mirroring proves advantageous. These results provide a practical tool for the selection of configurations that minimize energy losses and promote a more sustainable operation of high-current electrical systems.
The present report documents the work developed during the on-site internship at the company Alferpac - Projectos, Assistência e Obras Públicas, S.A., in Benedita, within the scope of the conclusion of the Master’s in Electrical Engineering - Energy and Automation, at the School of Technology and Management of the Polytechnic Institute of Leiria. The internship focused on two main fronts: the execution of electrical systems project activities (site surveys, sizing of electrical panels, cable path routing, lighting projects, current calculations and sizing of cables and respective protections, ventilation of transformer stations and power increases) and the development of a study about the problem of mutual inductances when single-core cables are used in three-phase systems. The study analyzed comparatively eight configurations of three-phase conductors in parallel (single-core cables), distributed by four main geometries (rectangular, stratified, horizontal and triangular), with the objective of minimizing circulation currents and Joule effect losses. The methodology was based on the development of a computational model in Excel, based on the scientific article by S.-Y. Lee, which calculates mutual inductances and quantifies the performance through the loss factor (δ𝑡). The results revealed a clear performance hierarchy: the mirrored rectangular arrangement (Scenario 1-A) stood out as the optimal solution (δ𝑡 = 1.00055), while the permuted stratified layout (Scenario 2-B) recorded the worst performance (δ𝑡= 1.03264). It was also found that the effectiveness of phase permutation is strongly dependent on the geometry: in compact arrangements, structural symmetry is preferable; in the horizontal geometry, mirroring proves advantageous. These results provide a practical tool for the selection of configurations that minimize energy losses and promote a more sustainable operation of high-current electrical systems.
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Indutâncias mútuas Correntes de circulação Condutores em paralelo Sistemas trifásicos Perdas por efeito Joule Otimização energética
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Sem licença CC