A fundamental approach to transformer thermal modeling. II. Field verification

Swift, G.W.; Molinski, Tom; Bray, Richard J.; Menzies, R.W.

doi:10.1109/61.915479

Cited by 142 publications

(90 citation statements)

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“…The heat generated by both noload and load transformer losses are represented by two ideal heat sources [19], [20].…”

Section: Thermal Models Of Power Transformers Thermal Model Of Oil Pomentioning

confidence: 99%

“…Figure 1. Thermal over all circuit models where: q tot is the total losses; q heat generated in the winding; R ambient temperature; θ hs is the hot spot temperature; θ R th-hs-oil is the non linear winding to oil thermal resistance; C capacitance and Cth -oil is the oil load and load transformer losses are represented by two ideal heat sources [19], [20].…”

Section: Thermal Models Of Power Transformers 1 Thermal Model Of Oilmentioning

confidence: 99%

“…The convective heat transfer coefficient between the SF 6 insulating gas and the inside of the transformer tank, hgt, can be evaluated using similar procedure equations (12) to (20) still apply without modification, however the Rayleigh number are determined from the expression: The following correlation has been proposed for conditions which result in combined free and forced convection between the tank inside surface and the SF 6 insulating gas [23]: …”

Section: Thermal Model Of Sf6 Power Transformermentioning

confidence: 99%

“…The ambient temperature is represented as ideal temperature source [19], [20]. The nonlinearities i.e., oil viscosity and other transformer oil parameter changes and loss variation hermal resistances [17].…”

Section: Thermal Models Of Power Transformers Thermal Model Of Oil Pomentioning

confidence: 99%

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Comparasion between Oil Immersed and SF6 Gas Power Transformers Ratings

2012

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“…The heat generated by both noload and load transformer losses are represented by two ideal heat sources [19], [20].…”

Section: Thermal Models Of Power Transformers Thermal Model Of Oil Pomentioning

confidence: 99%

Section: Thermal Models Of Power Transformers 1 Thermal Model Of Oilmentioning

confidence: 99%

Section: Thermal Model Of Sf6 Power Transformermentioning

confidence: 99%

Section: Thermal Models Of Power Transformers Thermal Model Of Oil Pomentioning

confidence: 99%

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Comparasion between Oil Immersed and SF6 Gas Power Transformers Ratings

2012

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“…Os modelos térmicos de transferência de calor entre o óleo e o meio refrigerante e entre o enrolamento e o óleo, bem como a expressões correspondentes são detalhados por Swift [25].…”

Section: Método De Solução De Expressões Exponenciaisunclassified

Experiências do desenvolvimento de transformador para alta temperatura baseado em isolação semi-híbrida e óleo vegetal isolante.

Silva¹

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AGRADECIMENTOSPrimeiramente agradeço a Deus, cujas bênçãos e misericórdias tem se estendido de geração em geração sobre aqueles que o temem e amam.A Universidade de São Paulo, através da Escola Politécnica e seu corpo docente, que me concederam a oportunidade de tão grande enriquecimento didático e intelectual.A meu orientador, Prof. Dr. José Antônio Jardini, pela compreensão, ensinamentos, incentivo nas horas difíceis e orientação essencial ao sucesso deste trabalho.Ao Prof. Luiz Natal Rossi, pela confiança, incentivo e apoio.A minha esposa, Rosangela, pela compreensão, apoio incondicional, mesmo diante de tantas dificuldades, mas diversas vezes abdicou dos seus sonhos para investir no meu ideal tem se mostrado firme e convicta quanto ao êxito deste trabalho.A minha mãe Doracy, minha avó Jovelina, minha avó Elisa (in memorian), minha irmã Kátia, meus tios Gilson e Josefa pelo incentivo a nunca desistir diante das dificuldades.Aos meus filhos Carlos Matheus, Ysadora e Beatriz pela fonte de inspiração.Aos amigos que intercedem em meu favor junto ao Criador de todas as coisas.A todos que, no presente ou no passado, contribuíram para a execução deste trabalho, aos colegas de empresa Ricardo Gedra, Julio Cesar P. Mello, Marcos Paulo de Oliveira Castro, Rodrigo Tesso, Arnaldo Miyashiro, João Oliveira, Márcio Sanches, Alexandre Leite, Marcello Viana e especialmente, ao Engenheiro Carlos Ossamu Kajikawa pelo apoio ao desenvolvimento técnico e intelectual e demais integrantes do corpo técnico da AES Eletropaulo.As empresas AES Eletropaulo, ANEEL, ao corpo técnico das empresas WEG, ABB, Treetech, Laboratório Diagno, CPFL e a Fundação para o Desenvolvimento Tecnológico da Engenharia, em especial, à Paula Kayano, pelo incentivo ao estudo, desenvolvimento e pesquisa. RESUMOO transformador de potência é um importante equipamento utilizado no sistema elétrico de potência, responsável por transmitir energia elétrica ou potência elétrica de um circuito a outro e transformar tensões e correntes de um circuito elétrico. O transformador de potência tem ampla aplicação, podendo ser utilizado em subestações de usinas de geração, transmissão e distribuição.Neste sentido, mudanças recentes ocorridas no sistema elétrico brasileiro, causadas principalmente pelo aumento considerável de carga e pelo desenvolvimento tecnológico tem proporcionado a fabricação de um transformador com a aplicação de alta tecnologia, aumentando a confiabilidade deste equipamento e, em paralelo, a redução do seu custo global.Tradicionalmente, os transformadores são fabricados com um sistema de isolação que associa isolantes sólidos e celulose, ambos, imersos em óleo mineral isolante, constituição esta que define um limite à temperatura operacional contínua.No entanto, ao se substituir este sistema de isolação formado por papel celulose e óleo mineral isolante por um sistema de isolação semi-híbrida -aplicação de papel NOMEX e óleo vegetal isolante, a capacidade de carga do transformador pode ser aumentada por suportar maiores temperaturas. Desta forma, o envelh...

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IVUS: Cracking the “Code” in the wall

Schainfeld

2008

Cathet Cardio Intervent

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Percutaneous balloon angioplasty (PTA) and endovascular stenting techniques have rapidly evolved during the past decade. The advances in technology, including guidewires with the ability to traverse long total occlusions safely, balloon catheters, and refinements in stent design has afforded the interventionalist a broad array of tools in his arsenal to optimize technical and clinical results in their patients. As a result, the vascular community as a whole has embraced these techniques and adopted their formidable role in their respective practices, including our vascular surgical colleagues. Acknowledging there has been historically a dearth of evidence-based literature supporting the results of these endovascular procedures involving different vascular beds, angioplasty, and stenting in the aorto-iliac axis has enjoyed excellent technical, clinical success along with durable long-term patency outcomes. These procedures are not only well-tolerated and safe, but rival the results of bypass surgery in this vascular bed that are associated with much higher morbidity, complications, and mortality [1].In the interventionalist's search for the holy grail, the ''perfect'' angiographic result, he has explored numerous therapeutic strategies to facilitate achieving this elusive prize. Intravascular ultrasound (IVUS) has been a tremendous tool when appropriately utilized by the skilled and experienced interventionalist in uncovering many of the secrets of balloon angioplasty such as to show the way it works, its mechanisms and an invaluable resource to overcome the methodological limitations of contrast angiography [2]. Furthermore, it has been demonstrated to optimize the final results following PTA and stenting in both the coronary and peripheral vasculature [3,4].In this issue of CCI, Hara and Nishino report two cases of infrarenal aortic stenosis that were successfully stented with the use of IVUS guidance to achieve technical success in both patients [5]. They utilized IVUS technology to overcome the inherent limitations imposed by contrast angiography, notably, the propensity to underestimate the degree of stenosis. In each respective case, equivocal findings were apparent to the operators as to the severity of the lesion, described as ''shaggy and fuzzy moderately stenotic'', and in the second case, it was difficult to discern as to the etiology of the pathophysiology demonstrated on angiography representing an aortic dissection with a ''flaplike'' structure in the distal aorta. In both cases, employment of IVUS confirmed that the lesions were composed of very heavily calcified plaque, consistent with advanced atherosclerosis. In addition to clarifying the morphology of the lesions, they were able to quantitatively assess the minimum lumen diameter, reference diameter of the proximal and distal aspects of the vessels, in concert with acquiring the total length of the diseased segment involved. They acknowledged the difficulty imposed by the equivocal findings on angiography as the solo diagnostic modality and subs...

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A fundamental approach to transformer thermal modeling. II. Field verification

Cited by 142 publications

References 1 publication

Comparasion between Oil Immersed and SF6 Gas Power Transformers Ratings

Comparasion between Oil Immersed and SF6 Gas Power Transformers Ratings

Experiências do desenvolvimento de transformador para alta temperatura baseado em isolação semi-híbrida e óleo vegetal isolante.

IVUS: Cracking the “Code” in the wall

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