Base Knowledge
Electrical Circuit Theory I and II
Electrical Machines
Teaching Methodologies
Theoretical classes with exposition of the subjects, drawing attention to the most relevant aspects and making the connection between each subject and the others. Interpellation of students on the subject in order to arouse curiosity, remember and link previous knowledge. Presentation of some videos and animations that illustrate the concepts and/or applications.
Practical/Laboratory Classes. These classes are of two types: Exercise solving classes, which implement the models presented in the theoretical classes, allowing the calculation of the parameters of the machines studied from test results and their operating regimes; and laboratory experimentation classes where the classic tests of the studied machines are carried out.
Learning Results
Goals
The main aims of this course unit are:
Understand the steady state operation of direct current machines, synchronous machines and special electrical machines of more common use (universal motor, permanent magnet motor and reluctance motor). Knowledge of mechanical construction, principle of operation and equivalent circuits of dc machines and synchronous machines. Familiarize students with these electrical machines in electrical machines laboratory environment.
Skills
At the end of this course unit the learner is expected to be able:
To test, connect and work with dc machines and synchronous machines.
To design and conduct experiments, as well as to analyze and interpret data.
To choose technical solutions and participate in projects to implement and maintain these machines.
Program
1. DC machines
Mechanical construction. Principle of operation. Armature windings. Emf equation. Armature reaction. Theory of commutation. Power balance, developed torque, and efficiency. Excitation systems. Characteristics of the separately excited, shunt, series and compound generators. Characteristics of the separately excited, shunt, series and compound motors. Starting, braking and reversing operation of dc motors. Speed regulation.
2. Synchronous machines
Principle of operation. Physical constitution. Ac windings. Induced emf equation. Time and space harmonics. Armature reaction. Synchronous generators: Load operation. Economic tests and generators characteristics. Equivalent circuits. Parallel operation. Synchronous Motors: Power and torque for single-phase and three-phase motors. Effects of excitation and load. Power factor correction. Start of synchronous motors.
3. Special-purpose electric machines
Universal motors, Permanent-magnet motors. Reluctance motors.
Curricular Unit Teachers
Paulo José Gameiro PereirinhaGrading Methods
Access Conditions and Attendance Excuse
The practical classes are divided into 50% theoretical-practical classes and 50% of laboratory classes.
In order to have access to the final exam of the curricular unit, is mandatory the cumulative presence in:
- 80% of the laboratory classes;
- 65% of the total of all class hours (60 hours of classes planned, means a minimum of 39 hours of participation in theoretical and practical classes).
For students of special schemes, namely those under the Worker-Student Statute, and for components with compulsory attendance and distributed assessment, it must be agreed between the person responsible for the curricular unit and the student, on the initiative of the student and at the beginning of the academic semester, a form of alternative functioning of these components, when the student cannot justifiably attend them at the scheduled times.
Conditions for Exam Admission
Students who have passed the laboratory component and fulfilled the number of attendances required in the previous point have access to the exam.
Evaluation Method
1. Theoretical and Theoretical-Practical Component (CTTP) - are evaluated by final exam, consisting of an individual written test, with a minimum grade of 8.5 points.
2. Laboratory Component (CL) - works on a mandatory attendance basis and includes a continuous assessment throughout the semester and a final test.
- Continuous assessment (AC), based on the Reports (it is mandatory to deliver 80% of the experimental works, within a week after completion; delays in delivery will be penalized), there may be a difference in grades between elements of the same group, in case of significant discrepancies in individual performance (work preparation, execution capacity, answer to questions, analysis and treatment of experimental results).
- Final test of individual assessment of knowledge (TL), to be carried out at the penultimate week of classes of the semester, addressing issues related to laboratory work / reports.
- The CL approval implies a minimum grade of 8.5 points and is obtained by the weighted average of the continuous assessment (weight 6) and the final knowledge assessment test (weight 4):
CL = (6 x AC + 4 x TL) / 10
Students who do not obtain the above mentioned minimums will be excluded from the final exam.
3. Final Classification
The final classification (CF) is calculated by the weighted average of the CTTP (weight 7) and the CL (weight 3), according to the following expression:
CF = (7 x CTTP + 3 x CL) / 10
Note: Students who do not obtain the minimums in the final exam will not be considered the laboratory grade, and the grade of the exam will be marked to 20 points.
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It will not be allowed to consult any formula sheet in the examinations (in case of particularly complex equations, these will be provided with the exam).
Internship(s)
NAO
Bibliography
Bibliography in Portuguese (available to students on paper in the Text Section and/or in digital format on the UC Moodle
Carvalho, J. (2010). Máquinas de Corrente Contínua. Coimbra: ISEC. (base text)
Carvalho, J. (2010). Máquinas Síncronas. Coimbra: ISEC. (base text)
Pereirinha, P. (2008a). Máquinas Eléctricas – Do Projecto e Análise às Aplicações (lesson submitted to the public examination juri for Coordinator Professor, not published). Instituto Superior de Engenharia de Coimbra, Coimbra.
Pereirinha, P. (2008b). Máquinas Eléctricas – Introdução (reduced version of the presentation for the public examination class for Coordinator Professor ). [PowerPoint slides].
Videos, photos and animations about electrical machines (mostly in English), presented by teachers.
Alternative Bibliography in English and Spanish (available at the ISEC Library)
– Fraile Mora, J. (2016). Máquinas Eléctricas, (8.ª ed.). Madrid: Garceta. (Spanish)
– Fraile Ardanuy, J., &, Fraile Mora, J. (2015). Problemas resueltos de máquinas eléctricas (2.ª ed.). Madrid: Garceta. (Spanish)
– Fitzgerald, A.E., Kingsley Jr., C., & Umans, S. (2005). Electric Machinery (6th edition). New York : McGraw-Hill.
– Chapman, S. J. (2011). Electric Machinery Fundamentals (5.a Ed.). Mcgraw Hill Higher Education.
– Sen, P.C. (2013). Principles of Electric Machines and Power Electronics (3.ª ed). Wiley.
– Ras, E. (2009). Transformadores de potencia, de medida y de protección (7.ª ed.). Marcombo. (Spanish)
– Boldea, I., & Nasar, S. A. (2016). Electric Drives (3.ª ed.). CRC Press.
– Syed A. Nasar, Electric Machines and Power Systems: Volume I, Electric Machines,McGraw-Hill Companies, 1995, ISBN13: 9780070459588.
– Nasar, S. A. (1998). Schaum’s outline of theory and problems of electric machines and
electromechanics (2nd ed.). New York : McGraw-Hill.
– Guru, B. S., & Hiziroglu, H. R. (2000). Electric Machinery and Transformers (3.ª ed.). New York: Oxford University Press.
– Slemon, G. R., & Straughen, A. (1982). Electric Machines. Addison-Wesley Publishing Company.
– Fogiel, M. ; Research and Education Association – The electrical machines problem solver : a complete solution guide to any textbook. Rev. print. Piscataway, NJ : REA, 1990 imp. 785 p. ISBN 0-87891-551-6