29904 - Elements of Electrical Engineering T

Learning outcomes

The course aims to lead the students to the understanding of the fundamental principles and main applications of Electrical Engineering. The concepts and methodologies relative to stationary and quasi-stationary Electromagnetism are presented. The main solution methods for the analysis of electrical circuits are discussed, in stationary, transient and sinusoidal regimes. A description of the characteristics and working principles of the main electrical machines is given (transformers, synchronous machine, induction machine). The working principles of the main components of an electric power system are illustrated. Basic concepts of electrical safety are also given.

Course contents

Electromagnetic fields: Main vector operators. Maxwell equations in differential and integral form. Electrostatics. Laplace and Poisson equations. The general problem of electrostatics, the theorem of corresponding surfaces, capacitors.

Electric circuits. Lumped parameter circuits. Kirchhoff laws. Main circuit components: resistors, inductors, capacitors, independent voltage and current sources. DC circuits. Resistors in parallel and in series. Delta-wye transformation. Methods of analysis of electrical circuits. Kirchhoff equations method. Nodal analysis. Mesh analysis. Effects superposition principle. Tellegen, Norton and Thevenin theorems. Study of transients in RC, RL and RLC circuits. Determination 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. Four wire systems: functions of the neutral wire.

Magnetostatics. Magnetic properties of matter. Diamagnetic, paramagnetic and ferromagnetic materials. Analysis of magnetic circuits. Hopkinson law. Self and mutual inductance coefficients. Equivalent circuit of a real inductor. Principles of electro-mechanical conversion of energy.

Electrical machines:

Fundamentals. Loss phenomena in electrical machines.

The transformer. Working principle. Internal and external equations. Equivalent circuits. Open circuit and short circuit tests of transformers. Measurement of the transformer efficiency.

Rotating magnetic field. Magnetic field generated by a stationary current flowing in one phase of the machine. Rotating magnetic field generated by a three phase winding system.

Induction machines. Working principle. Equivalence theorem. Mechanical and electromechanical characteristics. Single-phase induction machines.

Synchronous machines. Working principle. Synchronous generators and motors. Frequency and voltage tuning.

Electric power systems. General information on power systems. Main power system components. Different kinds of electric power plants. Main energy sources. Structure of a power grid, electrical energy storage systems, electric lines, protection devices. Fundamentals of electrical safety, direct and indirect contacts, grounding system, differential relay. Effects of electrocution on the human body. Static electricity problems in industrial environments.

Readings/Bibliography

G. Rizzoni, ‘'Principles and applications of electrical engineering'', McGraw-Hill.

Teaching methods

The course contents are presented during lectures in the classroom. Examples, applications and problems are also solved in the classroom. The students are required to attend laboratory experiences, in which two kinds of main activities are carried out, namely experiments on circuits (realization of simple circuits, measurement of resonance frequency, measurement of transformer efficiency) and computer simulations (dc circuits, transients, ac circuits).

Assessment methods

The exam consists of a written test and an oral test.  In order to be admitted to the oral test a minimum mark of 15/30 is required at the written test. In order to participate to the final exam, the students are required to attend the laboratory experiences.

Teaching tools

Notes for the course are available in Italian at the web address (access for students enrolled at the University of Bologna)

http://campus.cib.unibo.it/cgi/lista?sort=&groupby=&sort_type=&annoAccademico=2010&cognome=breschi&nome=&email=&codiceDocente=&filtro=&nav=d&Cerca=Cerca

 

Links to further information

http://www.die.ing.unibo.it/pers/breschi/marco.htm

Office hours

See the website of Marco Breschi