29904 - Elements of Electrical Engineering T

Academic Year 2018/2019

  • Docente: Marco Breschi
  • Credits: 9
  • SSD: ING-IND/31
  • Language: Italian
  • Moduli: Marco Breschi (Modulo 1) Pier Luigi Ribani (Modulo 2)
  • Teaching Mode: Traditional lectures (Modulo 1) Traditional lectures (Modulo 2)
  • Campus: Bologna
  • Corso: First cycle degree programme (L) in Chemical and Biochemical Engineering (cod. 8887)

Learning outcomes

Learn the methodologies necessary for the analysis of DC lumped parameter electric circuits. Acquire the basic knowledge required for the analysis of single-phase and three-phase sinusoidal electric circuits and magnetic circuits. Provide the fundamentals of electrical machines and electrical systems in general, with particular reference to applications in the chemical industry.

Course contents

Recommended Requirements / Advice

A prior knowledge and understanding of the following topics is required to attend with profit this course. Fluent spoken and written Italian is a necessary pre-requisite: all lectures and tutorials, and all study material will be in Italian.

The following basic knowledge in mathematics is required: linear algebraic equation systems, complex number operations, and differential and integral calculus. Physics knowledge is also required, with particular reference to electromagnetism. This knowledge can be acquired by passing the basic exams of mathematics and physics at the School of Engineering.

Program

The course program is divided into the sections below.

Electromagnetic fields.

Main vector operators. Basic definitions. Maxwell equations in integral form. Electrostatics. Laplace and Poisson equations. Capacitors.

Lumped parameters electric circuits.

Kirchhoff’s laws. Main circuit components: resistors, inductors, capacitors, independent voltage and current generators. Stationary regimes. Resistances in parallel and in series. Delta-wye transformation. Methods of analysis of electrical circuits. Kirchhoff equations method. Nodal analysis. Mesh analysis. Effect superposition principle. Tellegen, Norton and Thevenin theorems. Study of transients. RC, RL, RLC circuits. Definition of the initial conditions for the analysis of transients. Sinusoidal regimes. Ohm symbolic law and concept of impedance. Kirchhoff symbolic laws. The symbolic method for the analysis of electric circuits in sinusoidal regimes. Power in sinusoidal regime. Three phase systems. Wye and delta components. Power in a three phase system.

Magnetostatics.

Magnetic properties of matter, diamagnetic, paramagnetic and ferromagnetic materials, magnetic circuits, self and mutual induction coefficients. Hopkinson’s law.

Electrical machines

Principles of electro-mechanical conversion of energy. Loss phenomena in electrical machines.

The transformer. Working principle. Field hypotheses. Internal and external equations. Equivalent circuits. Transformers working in open circuit and short circuit. Measurement of the efficiency. Rotating magnetic field.

Induction machines. Working principle. Internal and external equations. Equivalence theorem. Mechanic and electromechanic characteristics.

Synchronous machines. Working principle. Internal and external equations.

Power systems.

General information on power systems. Main power system components. Different kinds of electric power plants. Main energy sources, electric lines, protection devices, ground plant.

Readings/Bibliography

G. Rizzoni “Elettrotecnica. Principi e applicazioni”, Mc Graw-Hill, Terza Edizione, 2013 o edizioni successive.

K. Alexander, M. Sadiku, “Circuiti elettrici”, Mc Graw-Hill, 2012, o edizioni successive.

Ghigi, Martelli, Mastri “Esercizi di Elettrotecnica”, Progetto Leonardo, 2000

Hambley, “Elettrotecnica”, quarta edizione, Pearson, 2009.

Teaching methods

The course contents are illustrated during the lectures. Two hours of lecture per week will be dedicated to the solution of exercises. Six laboratory practices are also required, including three experimental exercises and three computer exercises. Experimental exercises will consist in the realization of DC and AC circuits and the measurement of transformer efficiency. Computer exercises will address the solution of DC, AC circuits and transients, using commercial software.

Assessment methods

The exams will concern the topics of the course program.

The lecture notes are a didactic tool, but do not replace the lectures: the whole course program developed in the lectures is a matter of examination.

During the course, two partial exams are scheduled, approximately one at the half of the course, and the other at the end.

Each partial test involves two exercises and one or more theoretical questions.

The first partial test will include two exercises concerning DC Electrical Circuits and Transients in Electric Circuits.

The two exercises of the second partial test will refer be arbitrarily selected between the following three types: Magnetic Circuits, AC Electric Circuits, Three Phase Networks.

The time available to treat the theoretical questions is about 20 mins per question. The first partial test includes one theoretical question, whereas the second partial test includes two questions.

The answer to each question will have to be contained in approximately one or two sides of the protocol sheet (too long answers will be a penalty factor for the final mark).

The questions refer to: illustration of subjects or demonstrations.

If a topic is required to illustrate a subject, the exposition must be synthetical, only reporting the essential points of the discussion and citing the necessary laws.

In the case of demonstrations, the candidate will qualitatively trace the diagrams or reference graphs, write the necessary expressions and specify, where applicable, the validity limits of the requested demonstration.

During the written tests, the use of any didactic materials (books, lecture notes) is not allowed. The use of a calculator is allowed, but only for the solution of exercises.

The elements to evaluate the anwers to the theoretical questions will be the following:

· The correctness of the answers;

· The clarity, completeness and synthesis of the answers.

The results of the written tests will be made available on the AMS Campus website.

Students who have achieved the passing grade in partial exams (a mark greater than or equal to 18/30 on both the exercises and the theory) will be able to choose whether to sum up the overall grade obtained or to hold an oral exam.

If the passing grade is not reached, but the final score is greater than or equal to 15/30, the student will be admitted to the oral examination.

In case the final mark is less than 15/30, the student will not be admitted to the oral examination, and will have to undertake the complete exam.

The complete exam consists of a written test and an oral exam. The written test consists of two exercises. To gain access to the oral exam, the candidates must reach a mark greater than or equal to 15/30.

The two exercises of the written test of the complete exam will be arbitrarily selected between the following topics: DC Electric Circuits, Transients in Electric Circuits, Magnetic Circuits, AC Electric Circuits, Three Phase Networks.

Teaching tools

The lecture notes of the course are available on the website Insegnamenti OnLine of the University of Bologna (https://iol.unibo.it). Presentations given during the course and examples of written tests are also available on this website. 

Office hours

See the website of Marco Breschi

See the website of Pier Luigi Ribani