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Electrical Machines

Code:

LEEC31125

Sigla:

ME

Áreas Científicas
Classificação	Área Científica
OFICIAL	Electric Power Systems

Ocorrência: 2022/2023 - 2S

Ativa?	Yes
Unidade Responsável:	Departamento de Engenharia Eletrotécnica
Curso/CE Responsável:	Electrical and Computer Engineering

Ciclos de Estudo/Cursos

Sigla	Nº de Estudantes	Plano de Estudos	Anos Curriculares	Créditos UCN	Créditos ECTS	Horas de Contacto	Horas Totais
EEC	22	Plano de Estudos	2	-	6	75	162

Língua de trabalho

Portuguese

Objetivos

The subject intends to contribute to the scientific formation of the student in the area of ​​Electrical Machines, in the study in steady state of the three-phase induction machine (MIT), the single-phase induction motor (MIM) and the Transformer (TR).

Resultados de aprendizagem e competências

Upon completion of this course, the student should be able to:
1-Understand/explain the constitution of MIT, MIM and TR, justify the respective operating principles with laws and rules;
2-Obtain/estimate the parameters of the equivalent schemes of MIT, MIM and TR in steady state.
3-Apply the MIT, MIM and TR mathematical model to predict operating points.
4-Analyze the powers at stake and predict the performance of MIT, MIM and TR;
5- Use Matlab to simulate the MIT and TR operating regimes in steady state.
6- Perform laboratory procedures and practices in order to experiment, validate and consolidate theoretical knowledge.

Modo de trabalho

Presencial

Pré-requisitos (conhecimentos prévios) e co-requisitos (conhecimentos simultâneos)

It is important for the student to have prior knowledge of direct current and alternating current electrical circuit analysis, electromagnetism and magnetic circuits, and operations with complex numbers.

Programa

INTRODUCTION
1. Principles and laws of Electricity and Electromagnetism applied to Eletrical Machines (Laws d'Ohm, Hopkinson, Kirchhoff. Lorentz-Laplace force. Ampère's law and Faraday's law. Rules for determining directions).
2. Fundamentals of Electromechanical Energy Conversion.

I. THREE-PHASE INDUCTION MACHINE.
1. Working principle of an induction machine.
2. Constitution of the induction machine. Stator equation. Rotor equation.
3. Tests to determine parameters and reduce the rotor to the stator.
equivalent schemes
4. Powers and Torques. Energy Diagram. Performance.
5. Mechanical characteristic, maximum torque and corresponding slip.
Electromechanical characteristic of the current. classes. starts.
6. Three-phase induction generator. Working principle. self-excitement with
capacitors.
7. Criteria for selecting an induction machine.
II. SINGLE PHASE INDUCTION MOTOR
1. Constitution and operating principle. Double rotating field theory.
2. Powers and Torques. Equivalent scheme. Energy Diagram.
3. Mechanical characteristic.
4. Starting aids.
III. SINGLE-PHASE TRANSFORMER.
1. Constitution. Windings. Ferromagnetic core. Coefficient of stacking.
2. Principle of operation. Convention.
3. No-load operation.
3.1. Perfect and ideal transformer.
3.2. Electromotive force. Relationship of transformation.
3.3. Real transformer. Leakage flow. Winding resistors. No load current. Component of magnetization and loss component in iron. Equivalent scheme. Phasor diagram.
4. Charging operation.
4.1. Perfect and ideal transformer. Approximate relations between currents and tensions.
4.2. Real transformer. Scheme equivalent of Steinmetz. Phasor diagram. Reduction of quantities from secondary to primary. Voltage drops on load.
5. Transformer tests. No load test. Short-circuit test. Short-circuit voltage. Tests under load. Characteristic curves. Approximation of Kapp.
6. Energy diagram. Constant and variable losses. Efficiency curve. Maximum efficiency.
7. Understanding the constitution, operation and use of autotransformers.

IV - THREE-PHASE TRANSFORMER
1. Three-phase transformers. Constitution. Magnetic Fluxes. Working principle.
2. Winding connection designations. Clock notation. Transformation ratio.
3. Parallel of three-phase transformers. Requirements for connection.  Load sharing.

Bibliografia Obrigatória

M. Gaspar Guerreiro; Máquinas Trifásicas de indução, ESTSetúbal, 2005
M. Gaspar Guerreiro; Introdução aos Transformadores, ESTSetúbal, 2003
A.E.Fitzgerald; Máquinas Eléctricas, McGraw-Hill do Brasil, 1975. ISBN: 0-07-090132-5 (Mediateca da ESTSetúbal)
Jesus Fraile Mora; Máquinas Elétricas, McGraw-Hill, 2003. ISBN: 84-481-3913-5

Métodos de ensino e atividades de aprendizagem

Theoretical-practical classes, where a teaching methodology is used in which pedagogical techniques of active learning are applied, involving the student more in the process of acquiring knowledge. On the one hand, it allows students, in the exercise of learning activities in the classroom environment, to interact and internalize the contents, developing appropriate attitudes and competences in line with the proposed objectives. On the other hand, the greater involvement of the student in the learning process and in the construction of their competences contributes to the development of their critical spirit and greater autonomy.

Laboratory classes, where practical works are carried out that allow the experimentation and validation of the subjects taught in the theoretical classes.

Software

Matlab
Octave

Tipo de avaliação

Distributed evaluation without final exam

Componentes de Avaliação

Designation	Peso (%)
Teste	65,00
Trabalho laboratorial	35,00
Total:	100,00

Componentes de Ocupação

Designation	Tempo (Horas)
Estudo autónomo	55,00
Frequência das aulas	75,00
Trabalho laboratorial	32,00
Total:	162,00

Obtenção de frequência

1- The continuous assessment regime
Students who intend to attend the UC under continuous assessment are required to carry out all assessments of the two components:
- Theoretical-practical component (Tp) is evaluated by tests. The Tp component grade is given by the average of the tests.

- Laboratory Component (L) with mandatory completion of laboratory work. The evaluation of the laboratories is composed of the performance in class and of the reports and other documents presented of the different laboratory works.


2- Assessment regime by exams with mandatory laboratory work
Students who choose the assessment system by exams will take a written test in which all the subjects corresponding to the Tp component will be evaluated. Examination tests are carried out at scheduled times at School level.

The minimum grade for the average of the Tests, the Laboratory Component and the Exam is 9.5 (nine point five points) .

3-Evaluation regime at the time of exams
The exam consists of two parts, one for the first part, and one for the second part. Students who did not pass the continuous assessment system and are obliged to take an exam for their approval, may decide not to take one of the parts of that exam and, in that part, they will be awarded the classification obtained in the corresponding test. The classifications obtained in the parts carried out in the exam replace those eventually obtained in tests for the calculation of the average Tp.

Fórmula de cálculo da classificação final

Final grade (NF) in the continuous assessment regime is given by:

NF = 65% Tp + 35% L;

The final grade (NF) in the assessment system by exams will be the weighted average of the classification obtained at the time of the exam (NE) and that obtained in the mandatory Laboratory component (L) or equivalent,

NF = 65% NE + 35% L ;

Students who have obtained NF ≥9.5 values ​​will be approved with the final classification (NF) determined by rounding up to units.

Melhoria de classificação

Once approved in continuous assessment, the student will only be able to improve the grade during the appeal period.

Observações

The contents and teaching materials to support the study can be found on the ME page on moodle. Students are registered by the RUC.

Students with special statutes must present their specific situation to the RUC, taking into account the objective implications of following the classes.