# FOUNDATIONS OF ELECTRICAL ENGINEERING

OVERVIEW

The course gives the essential elements for understanding of analysis and exploitation of the electromagnetic phenomena. In the first part of the course the instruments for static and quasi-static analysis by circuit methods are introduced. In the second part of the course the principal application aspects of exploitation of power electromagnetic phenomena are introduced: electrical motors, power electronics and power electrical systems.

## AIMS AND CONTENT

LEARNING OUTCOMES

The course is aimed to supply fundamental acquaintances and mathematical instruments for the study and the analysis of the electric circuits in direct current and alternating current domain; the electrical motors, the power electronic system, the electrical drives and the energy power systems.

AIMS AND LEARNING OUTCOMES

Attending lessons and exercises, the students will be able to:

- have knowledge relative to theoretical bases and application instruments for the analysis of electric circuits in steady-state and sinusoidal regime (single phase and three-phase systems);
- have superficial knowledge of the mathematical instruments for the analysis of electric circuits in time-domain;
- have knowledge of the main physics phenomena who subtend to the operation of the electrical machines (transformers, synchronous and induction machines);
- have knowledge of first rudiments for the analysis of transformers and induction motors in operation;
- have knowledge of the main aspects relevant to power electronics and static converters;
- have knowledge, in descriptive way, of electrical drives and their applications;
- have knowledge of main aspects relative to the analysis of the electric power systems;
- have knowledge of simplified analysis techniques for low-voltage electric systems, with detailed knowledge about evaluation of: efficiency, voltage drop, power evaluations. They will know also the problems relevant to low-voltage power factor correction and power capacitors evaluation.

PREREQUISITES

Basics knowledge of Calculus and Physics.

Teaching methods

The course mainly develops through frontal lessons with computer and audiovisual aids (70 hours). Moreover sessions of exercises carried out in classroom are provided (about 30 hours). The students who attend the course must record themselves to the site AulaWeb, enrolling themselves to the course. In such a way they will have access to didactic material of the course, will receive via email communications of the teacher and will have access to the results of the written tests.

For the development of the exercises in classroom, two hours weekly , in preparation of the practical tests, will be scheduled. To leave, indicatively, from the second week of October.

SYLLABUS/CONTENT

*Circuits*

- Introduction – Electrical power transmission - Electrical generators, electrical users, Electrical lines.
- Electromagnetic phenomena: General approach to the solution of the electromagnetic problems - Electric charge - Electrical current - Conductors - Continuity Law - Measure of the electrical current: ammeter - Electric field – Electric Voltage - Measure of the electric voltage: voltmeter.
- Electrical Conduction: Ohm’s and Joule’s Laws - Electrical resistivity and conductivity - Conductors of generic form - Bipolar resistor - Characterization of a bipolar resistor.
- Electrical Generators: Introduction – Behaviors of generators in open circuit - Behavior of generators with loads - Energy balance of generators – Electrical generators types.
- Bipolar devices and energy balance: Introduction – Equations of bipolar devices – Special bipolar devices (short circuit and open circuit) – Rate of electrical energy - Measure of the electrical power: wattmeter.
- Electrical network Properties: Introduction - Regime of operation (stationary, variable, transitory) - Analysis of the electrical networks - Topology of the networks - Kirchhoff’s Laws – Network analysis methods.
- Steady state analysis: Introduction – Bipolar devices connected in series – Series connection of an ideal voltage generator and a resistor - Resistors in series: equivalent resistance – Bipolar devices connected in parallel - Parallel connection of an ideal current generator and a resistor - Resistors in parallel: equivalent conductance - Network of resistors: equivalence concept - Star-delta transform – Steady-state analysis Methods - Superposition method – Maxwell’s method - Network reduction - Substitution Theorem – Thevenin’s transform – Norton’s transform – Millmann’s Formula – Power matching - Maximum power transfer.
- Dielectric phenomena – Capacitor : Introduction – Gauss’s Law - Capacitor – Parallel-plate capacitor- Bipolar capacitor – Capacitor in steady-state regime - Capacitor in transient regime - electrostatic Energy - Series and parallel of capacitors - Displacement current.
- Magnetic phenomena - Inductor: Introduction - Magnetic materials - Ferromagnetic materials - magnetic Induction - Faraday-Neumann’s Law - Inductors – Inductor coils - Mutual inductors – Bipolar inductors and two port inductors - Inductors in steady-state regime - Inductors in transient regime - Magnetic energy - Series and parallel of inductors.
- Sinusoidal steady-state networks: Introduction – Sinusoidal quantities: Phasors and sinusoids – Phasors graphical operations - generalized Ohm’s Law - Impedance – Sinusoidal steady-state network analysis – Thevenin’s and Norton’s transforms - Power balance in steady-state sinusoidal regime (average power, reactive power, complex power) - Measuring instruments in a.c.
- Three-phase network analysis: Introduction - symmetrical three-phase voltages - Phase and line voltages – Three-phase balanced load – Currents in three-phase networks – Balanced load analysis – Single-phase equivalent - Powers in balanced three-phase systems.
- Magnetic circuits: Introduction - Reluctance – Ferromagnetic materials - Air gap - Magnetic circuit’s Laws - Network analysis of magnetic circuits.

*Electrical machines*

- Transformers: Single-phase transformers - Equivalent circuit of the transformer – No-load (open-circuit) and short circuit tests – Power transformer on load - Three-phase transformers - Equivalent circuit of the three-phase transformer.
- Induction machines: Basic principles of a three-phase induction machine – Action of a three-phase induction machine - Simplified equivalent circuit - Speed-torque Characteristics – Starting of induction motors - Induction machine acting as generator.
- Synchronous Machines: Constructional features – Basic principles – No-load characteristics of a synchronous machine - Synchronous machine on load - Equivalent circuit of the synchronous machine - Electromechanical behavior.

RECOMMENDED READING/BIBLIOGRAPHY

Written support are available on-line on AulaWb site. There are various folder, where:

in folder "appunti del corso" are available for download pdf copies of teaching slides.

in folder "esercitazioni" are available for download pdf copies of solved exercises.

in folder "risultati delle prove scritte" are available for download pdf copies of past written exams.

It is also useful consulting of following books available from school CBA:

M. Guarnieri, A. Stella: “Principi ed applicazioni di Elettrotecnica (volume primo)”, Edizioni Libreria Progetto Padova.

C. K. Alexander, M.N.O. Sadiku: “Circuiti elettrici”, McGraw-Hill, ISBN 88 386 0853-9.

C. A. Desoer, S. Kuh: “Fondamenti di teoria dei circuiti”, Franco Angeli Editore, Collana di Ingegneria Elettrica.

## TEACHERS AND EXAM BOARD

**Ricevimento:** Date due by e-mail or phone call to teacher:
Prof. Paolo Molfino Dept. DITEN
office: Via Opera Pia 11 (ex-CNR), 3^ piano
Phone: 010 3532713 e-mail: paolo.molfino@unige.it
On course website students can find map to find teacher’s office.

Exam Board

PAOLO MOLFINO (President)

PIETRO OSCAR VENTURA

MANSUETO ROSSI

MARIO NERVI

GIULIO BARABINO

MASSIMO BRIGNONE

## LESSONS

Teaching methods

The course mainly develops through frontal lessons with computer and audiovisual aids (70 hours). Moreover sessions of exercises carried out in classroom are provided (about 30 hours). The students who attend the course must record themselves to the site AulaWeb, enrolling themselves to the course. In such a way they will have access to didactic material of the course, will receive via email communications of the teacher and will have access to the results of the written tests.

For the development of the exercises in classroom, two hours weekly , in preparation of the practical tests, will be scheduled. To leave, indicatively, from the second week of October.

## EXAMS

Exam description

The exam requires positive evaluation on a written test followed by an oral examination.

**Written test**: two written tests will be scheduled during the period of lesson (compitini). Each test require the solution of an exercise (one hour). Other written tests will be scheduled during the periods of examinations (January-February and June-September). Each test requires the solution of two exercises (two hours).

For every proposed exercise it must be answered to three questions, each of which it is worth a point, for a total on the two exercises of 6 points. Admission to oral test requires total score turns out to be ≥ 4 on 6. Regarding the intermediate written tests, students attending the course for the first time are admitted.

The overcoming of written tests guarantees the admission to the oral tests until the first written test of the following academic year. Exceeded such term the written test must be newly old.

**Oral examination**: talk of approximately 30 minutes on practical examples (exercises) and theoretical arguments. Oral test will be possible during the periods of interruption of the lessons, the registration to the examination sessions with a restricted number is carried out by means of the online procedure. The registrations is opened beginning from the week precedence to that of the session of examination chosen. In lessons periods oral tests are provided on appointment basis, only for students who have finished the triennial cycle (students who have already attended the third year courses).

Assessment methods

The examination tests have the scope to assess the level of students preparation with detailed emphasis on the following aspects:

- acquaintances with respect to the main basics elements that characterize the study of the electric circuits (for example: concept of two-terminal network, Ohm’s and Kirchhoff’s laws, Thevenin and Norton transform, Millmann’s formulas, sinusoidal analysis, etc) –acquaintances evaluated during the oral test;
- ability to apply them on specific problems (solution of numerical exercises: written test);
- acquaintances with respect to the main applicative aspects of electromagnetism (for example: transformers, induction machines, power electronics, electric power systems) – acquaintances evaluated during the oral test;
- ability to analyze simple problems relevant to low-voltage electric power systems, who involve the analysis of transformers, induction motors, electricity end-users, low-voltage power factor correction (solution of numerical exercises: written test).

## FURTHER INFORMATION

Pre-requisites :

Basics knowledge of Calculus and Physics (recommended).