AC Power Systems Handbook

Whitaker, Jerry C.

doi:10.1201/9781315222028

Cited by 13 publications

(8 citation statements)

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“…Instead, here we see a rapid increase then a more gradual decay; in other words, the current pulse in Figure has the shape of the natural response of a series resistor-inductor-capacitor (RLC) circuit . The high-voltage power supply presumably provides the inductance in the circuit, as inductive filters are commonly used to reduce the ripple current in rectifiers . The current response of a series RLC circuit to a step change in the voltage is where V 0 is the initial capacitor voltage, L the inductance of the system, and s 1,2 are characteristic frequencies determined by the resistance R and the capacitance C as follows: As shown in Figure , the current predicted by eq fits the observed current pulse extremely well for appropriate values of R, L, and C. For the current data shown in Figure , the best fit values of s 1 and s 2 were −289 Hz and −290 Hz, respectively.…”

Section: Interpretation Of the Currentmentioning

confidence: 78%

Measurement of Charge Transfer to Aqueous Droplets in High Voltage Electric Fields

et al. 2017

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The electric charge acquired by aqueous droplets when they contact an electrode is a crucial parameter in experimental and industrial applications where electric fields are used to manipulate droplet motion and coalescence. For unclear reasons, many investigators have found that aqueous droplets acquire significantly more positive than negative charge. Extant techniques for determining the droplet charge typically rely on a hydrodynamic force balance that depends on accurate characterization of the drag forces acting on the droplet. Here we present an alternative methodology for measuring the droplet charge via direct measurement of the electric current. As the droplet approaches the electrode the current is observed to gradually increase, followed by a large pulse when the droplet makes apparent contact. We interpret the transient current signals as the superposition of the natural response of an RLC circuit and an induced current described by the Shockley-Ramo theory. Nonlinear regression of the observed current to the theoretical model allows for the droplet charge to be extracted, independent of any assumptions about the force balance on the droplet. We demonstrate that regression of the current signal yields charge values that are on average within 4% of charges measured via a force balance. We use the chronocoulometric methodology to investigate how the charge varies with the applied potential, and we demonstrate that deionized water droplets contacting planar electrodes acquire on average 69% more positive charge than negative charge.

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Section: Interpretation Of the Currentmentioning

confidence: 78%

Measurement of Charge Transfer to Aqueous Droplets in High Voltage Electric Fields

et al. 2017

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“…In a study of AC generators, the torque was converted to power with efficiency higher than 90% [29]. e efficiency was higher than the one recorded in this study due to the better conductivity nature of the heat transfer fluid used.…”

Section: Steam Turbine Characteristicsmentioning

confidence: 53%

Prototype Steam Turbine for Solar Power Production

Kawira

2020

Advances in Materials Science and Engineering

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Fabrication of a prototype direct drive steam turbine using locally available materials provides a means to supply power and process heat for off-grid areas, which are not accessible due to rugged terrain. The use of solar power technologies to provide clean power and heat will mitigate environmental pollution and global warming that are caused by combustion of fossil fuels and other carbon-based power sources. The energy density of fossil fuels is higher than that of nonconcentrated solar power, which makes them a better option compared to nonconcentrated solar power sources. The high cost of steam thermal turbines and the limited technical skills on utilization of local materials for steam turbine construction have hampered the realization of potential of producing both small- and large-scale power in Africa. The design of the single-stage blade wheel system solar thermal turbine was done using AutoCAD 2010. The blades were made from encapsulated rice husk particle boards, and the steam casing was made from 0.0015 galvanized black iron sheet. Compensation for more stages was done by sending the fluid exiting from the turbine into the solar collector for reheating. It was coupled to a single-phase generator and gearbox. The rotor was made of galvanized iron tube. The turbine’s average efficiency was obtained as 61.6% and average isentropic efficiency was 55.3%. The combined gearbox and generator approximate efficiency was 54.7%. Locally available heat transfer fluids were used for solar thermal collection. The prototype turbine was designed to produce 500 W of power. It had a heat rate ratio of 0.08. The turbine inlet conditions were as follows: average temperature of 112.8°C, average pressure of 2.7 × 105 Nm−2, average enthalpy of 3156 kJ/kg, and average steam flow rate of 243.3 kg/hr. Outlet conditions were as follows: outlet average temperature of 97.3°C, average steam flow rate of 102.0 kg/hr, average pressure of 1.20 × 105 Nm−2, and enthalpy of 2103 kJ/kg. With use of 6 M sodium chloride solution, the turbine inlet conditions were as follows: enthalpy of 3789.1 kJ/kg at a pressure of 3.0 × 105 Nm−2 and its enthalpy at exit was 2346.3 kJ/kg at a pressure of 1.05 × 105 m−2 which can provide process heat and power for off-grid areas.

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“…Do ponto de vista de infra-estrutura é sugerida a construção de uma subestação de entrada em alta tensão provida por duas LTs, vindas de barramentos distintos da concessionária de energia elétrica local [58]. Esta solução irá apresentar uma melhor relação custoxbenefício caso já exista infraestrutura da concessionária para recebimento de duas LTs vindas de pontos distintos do sistema em questão.…”

Section: Objetivo E Estratégia Para Qualidade Da Energiaunclassified

Aplicações de controle e supervisão distribuídas em subestações de energia elétrica através do uso de relés digitais de proteção

Netto¹

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Para a minha famíla, não pelo apoio, não por acreditarem, não por serem meu porto seguro, não por estarem sempre presentes, não por deixá-los orgulhosos, mas, sim, por serem A MINHA FAMÍLIA! Aos Engenheiros Mário Fernando Krebs Baltar e Edgar Luiz Predabom, sócios e diretores da Maintenance Service Engenharia de Manutenção Ltda., por terem me colocado no bom caminho da Proteção de Sistemas Elétricos de Potência, por terem sido meus primeiros mentores nesta área e exemplos excepcionais de conduta profissional e capacidade técnica. Aos Professores Celso Fabrício de Melo Jr. e Wanderley Szlichta, da Universidade Tecnológica Federal do Paraná, UTFPR, por terem me apoiado no início desta empreitada, que foi o mestrado, e por terem sido o meu primeiro exemplo de acadêmicos sólidos, respeitáveis e dedicados. Aos Amigos de longa data e Engenheiros Giancarlo Melchiori, Especialista em Proteção de sistemas elétricos, da Maintenance Service Engenharia de Manutenção Ltda., por todo apoio, ensinamentos, paciência e amizade dispensados ao longo do início da minha carreira como Engenheiro, Luis Fernando Kerscher, Engenheiro de Sistemas de Telecomunicações, da Companhia Paranaense de Energia, COPEL, e Vlademir Bandeira, gerente do contrato da Caixa Econômica Federal pela DELTA-SP Engenharia, por terem me ajudado nos preparativos para o ingresso no programa de mestrado, além de serem exemplos de profissionais competentes, capazes, criativos e determinados. Ao Professor Tit. Denis Vinicíus Coury, da Universidade de São Paulo, por me acolher no programa de Mestrado, por todas as oportunidades e facilidades oferecidas, pela liberdade de trabalho e opinião, pelos desafios propostos, pela orientação segura e fecunda. Ao Professor Dr. Mário Oleskovicz, da Universidade de São Paulo, por dispor do seu tempo ouvindo idéias, refinando textos, propondo desafios, criando oportunidades e orientando de forma sólida e produtiva este aluno. Ao meu amigo, e companheiro de mestrado, Juliano Coelho Miranda, por ser um exemplo de garra, dedicação, competência, determinação, criatividade, bom humor e paciência. Aos meus amigos de Mestrado Daniel Barbosa e Ricardo de Andrade Lira Rabelo, pelo apoio em ocasiões específicas. Aos Engenheiros Ricardo Abboud, da Schweitzer Engineering Laboratories, SEL, e Licinio Ribeiro de Miranda, da General Electric, GE, pelo apoio e informações partilhadas.

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AC Power Systems Handbook

Cited by 13 publications

References 0 publications

Measurement of Charge Transfer to Aqueous Droplets in High Voltage Electric Fields

Measurement of Charge Transfer to Aqueous Droplets in High Voltage Electric Fields

Prototype Steam Turbine for Solar Power Production

Aplicações de controle e supervisão distribuídas em subestações de energia elétrica através do uso de relés digitais de proteção

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