Electrotechnics

Scholar Year: 2019/2020 - 1S

Courses

Head Teacher Responsability Pedro José Ambrósio Lobato Head

Weekly workload Hours/week T TP P PL L TC THE EL OT OT/PL TPL S Type of classes 4 Lectures Type Teacher Classes Hours Theorethical and Practical classes Totals 1 4,00 Pedro Lobato   4,00

Teaching language

Portuguese

Intended learning outcomes (Knowledges, skills and competencies to be developed by the students)

The UC of Electrotechnics is a basic discipline in the field of engineering sciences. Learning the underlying physical methods and concepts aims to develop in students fundamental skills that allow them to understand the phenomena of electromagnetic nature and the main techniques of analysis of electric circuits in direct and alternating current.
It is also intended that the students be in possession of instruments (basic knowledge and bibliographical orientations) that allow the possible continuation and deepening of studies. In order to achieve the proposed goals, laboratory practice and problem solving are used to consolidate and complement theoretical knowledge.

Syllabus

1. Introduction to Electrotechnics
Background and objectives.
2.Electrostatics
Electric charge; Electrostatic force; Coulomb's law. Electric field and potential; Electric potential diference; Capacitors and dielectrics; association of capacitors.
3. Steady Current
Electric Current; resistance; Ohm's Law; Association of Resistances; Sources of Voltage and Current; Electric circuit; Power and Energy; Joule´s Law.
Direct current analysis (DC circuits): Kirchhoff’s laws, voltage and current dividers,superposition theorem,Thévenin and Norton theorems.
4. Magnetostatics
Classification of magnetic materials; Ampére's Law; Magnetic flux; Magnetomotive force; reluctance; Magnetic saturation; Solenoids and Coils; Analysis of Magnetic Circuits; Hopkinson's Law. Analogy between electric and magnetic circuits.
5. Variable Electromagnetic Field
Faraday's Law; Induction coefficients.Coefficient of self-induction and mutual induction; Principle of operation of the transformer; Principle of operation of motor and generators
6. Circuits in quasi-stationary Regime (AC circuits)
Fundamentals of AC circuits: sinusoidal time-varying quantities, complex amplitudes; average value and RMS value.
AC steady-state analysis: Circuit R, RL, RC and RLC; Concept of Impedance and reactance; Association of impedances; Active, Reactive and Apparent Powers; Power factor. Balanced three phase systems.

Teaching methodologies

In the classes of this UC, both theoretical-practical and laboratory, it will be sought to stimulate the active participation of the student in his learning process, making use of his critical spirit. In the theoretical-practical classes there will be a part associated with the presentation of the programmatic content of the UC, always supported in another part, associated with problem solving. In the laboratory classes the student will have the opportunity to carry out eight laboratory work.

Assessment methodologies and evidences

The evaluation comprises two components:
- two tests (or final exam) (with minimum frequency requirement foreseen in the CTeSP rules) and a minimum mark of 9,5 values ​​in the average of the tests (or the final exam), which evaluates the learning of concepts and problem solving;
-realization of eight laboratory work, including the respective reports and final discussion (35%, with a minimum grade of 9,5 values).

The evaluation of the laboratories is composed of two components, which complement each other:
AP- Evaluation of the preparation of the work to be performed.
AR- Evaluation of the performance in the accomplishment of the works, reports and oral discussion.
The final laboratory grade L is calculated by:
L = 0.25.AP + 0.75.AR

Final mark = 65% (TP) + 35% (L) ≥ 9,5


From the theoretical-practical (TP) classes, a T-score is obtained by performing two optional tests, T1, referring to the first part (Electrostatic + Steady Current) and T2, referring to the second part (Magnetostatics + Variable Electromagnetic Field + Circuits in Quasi Stationary Regime) or by exam. The T classification is obtained by the following expression rounded to the units, T = 0.5.T1 + 0.5.T2 or the result of the theoretical-practical examination.

The exam consists of two parts, one for the first part (10 values), and another for the second part (10 values). Students required to take an examination for their approval may decide not to take one of the parts of that exam and in this part they will be awarded the grade obtained in the corresponding test. The marks obtained in the parts carried out, replace those obtained in tests.
Students who have L≥9.5 and T≥9.5 will be approved with the C-rating determined by rounding to the units of: C = 0.35.L + 0.65.T.
The exams take place at times scheduled at the school level.

Bibliography

Main Bibliography
Slides, theoretical sheets and problem sheets to support theoretical-practical classes.

Complementary Bibliography
Introdução à teoria da Eletricidade e do Magnetismo, Nelson Martins – Editora Edgard Blucher Ltda.;
Circuitos Eléctricos, LIDEL, Vitor Meireles; ISBN 972-757-305-3
Electromagnetismo, 310 Problemas Resolvidos, SchaumMcGraw-Hill, Joseph A. Edminister. ISBN 0-07-450131-3

Observations

The semester consists of 19 weeks, 16 teachings weeks (30 TP classes, 10 classes will be in a laboratory environment) and 3 preparation and evaluation.
The weekly classroom hours comprise 4 hours theoretical-practical (4TP) which makes a total of 60 hours over the course of 16 weeks.
For each theoretical-practical and laboratory class, the student devotes 2.5 hours of study (understanding and applying concepts, solving problems, preparing laboratory work). Autonomous study (TP): 30x2,5h = 75 hours.
In the weeks (3) of exams the student uses 8 hours per week for preparation. Total: 3x8 = 24 hours.
Classroom assessment (1 exam): 3.0h.
The total number of hours worked is 162 hours, giving a total of 6 ECTS credits.