Teachings

Select Academic Year:     2016/2017 2017/2018 2018/2019 2019/2020 2020/2021 2021/2022
Professor
BARBARA CANNAS (Tit.)
Period
Second Semester 
Teaching style
Convenzionale 
Lingua Insegnamento
ITALIANO 



Informazioni aggiuntive

Course Curriculum CFU Length(h)
[70/77]  CHEMICAL ENGINEERING [77/00 - Ord. 2020]  PERCORSO COMUNE 6 60
[70/78]  MECHANICAL ENGINEERING [78/00 - Ord. 2019]  PERCORSO COMUNE 6 60

Objectives

The basic objective of this course is to introduce students not specialists in the field to the fundamental electric circuit theory and its core applications. The students will acquire basic knowledge and skills necessary for the analysis of electrical circuits in steady state and sinusoidal steady state, single phase and three phase.
basic elements concerning the principle of operation and the circuit model of the transformer and the induction motor shall also be provided.

Knowledge and understanding
Knowing and understanding the behavior of steady state and sinusoidal steady-state electrical circuits single phase and three phase, and the methods of analysis. Knowing and understanding the problem of the power factor correction of electrical loads. Knowing the operating principle and constructive characteristics of the transformer. Knowing the principle of operation of the asynchronous motor and the problems related to the starting and speed control. Understand the equivalent circuits describing the electromagnetic behavior of the transformer and of the asynchronous motor.

Applying knowledge and understanding
Choose and apply the most suitable methods of analysis for electrical circuits in steady state and sinusoidal, steady state, single phase and three phase; be able to size the capacitor banks for the power factor correction, choose a transformer.

Communication
Ability to communicate with technical terms proper of the electrical engineering, ability to use graphical representations for the description of electrical circuits, transformers or asynchronous motors. Ability to describe, in both oral and written formats, the goals, the process and the results of the adopted procedures.

Making judgments
Having the ability to correctly interpret and verify the obtained results.

Lifelong learning skills
Be able to apply their knowledge to different contexts from those presented during the course, and deepen the topics using materials other than those proposed as the IEC standards or technical texts.

Prerequisites

Knowledge of the basic topics of the following courses: Calculus I, Calculus II, Physics I, Physics II, Geometry and Algebra.

Contents

Introduction:
Systems of units
Charge and Current
Voltage
Power and Energy
Circuit elements

DC networks
Passive and active sign convention
Ohm’s Law
Nodes, Branches, and Loops
Kirchhoff’s Laws
Equivalences: Delta to Wye and Wye to Delta Conversion, Series resistors and Voltage division, Parallel resistors and Current division
Superposition
Thevenin’s and Norton’s Theorems
Millmann’s theorem
Maximum Power Transfer
Network Analysis: Nodal analysis and Mesh analysis


AC Steady State analysis:
Introduction
Representations of sinusoidal signals as a function of time, complex and phasor representation
The symbolic method
Network components and their constitutive equations: Resistor, Capacitor, Inductor, Sources
Impedance and admittance
Instantaneous Average and Reactive power, Complex power, Apparent power
Boucherot theorem
Maximum Average Power Transfer
Steady state network analysis: Nodal analysis and Mesh analysis.
Thevenin's and Norton’s theorem.
Conservation of AC power
Power Factor Correction
Dangers of Electricity
Three-Phase Circuits

Electromagnetism
Magnetic fields in vacuum: Biot–Savart law, Ampère's law, Magnetic flux, self-inductance and mutual inductance.
Electromagnetic induction: Lenz’s Law, Induced electromotive force (emf) and Magnetic forces on moving charges.
Magnetic fields in materials: magnetic properties of materials (Diamagnetism, Paramagnetism, Ferromagnetism), Magnetic energy and Hysteresis loop, Hysteresis losses, eddy current losses.

Transformer
Ideal coupling and ideal transformer
Non ideal coupling
Coupled circuits and simplified model
Magnetically coupled circuits through iron core and simplified model.
The real transformer
Equivalent circuit

Asynchronous motor
Working principle
The rotating magnetic field
Constructive characteristics: rotor and stator
Equivalent network

Teaching Methods

40 lecture hours
20 hours of exercises
Lessons are mainly held in the traditional way through the use of the blackboard, with the support of Power Point slides made available to students. The exercises of analysis of electrical networks are solved by the teacher and / or the students.
Examination simulations will be performed.
Lectures will be prevalently held in classrooms, also integrated with online teaching resources, by using specific online platforms managed by the University of Cagliari.

Teaching Methods

40 lecture hours
20 hours of exercises
Lectures will be prevalently held in classrooms, also integrated with online teaching resources, by using specific online platforms managed by the University of Cagliari.

Verification of learning

The assessment of learning outcomes attainment is performed through a written test and an oral interview. The score will also consider the quality of oral and written communication. The written test, aimed at evaluating firstly the operational capabilities, also includes one or more problems related to the analysis of power grids, magnetic circuits, transformers, asynchronous motors.
The test score is out of thirty, weighting the rating attributed to the different exercises according to the commitment required for their resolution. During the test it won’t be allowed to use only the scientific calculator, whereas it won’t be allowed the use of texts of any kind, mobile phones, tablets and computers. It won’t be allowed to candidates, to communicate with each other or with other people.
Students who pass the written test can access the oral test, in which the written report will be discussed and the degree of theoretical knowledge (electrical components, theorems for network analysis, principles of operation of the transformer and the induction motor, equivalent schemes) will be determined. Moreover, the communication skills of the student will be tested.
The text of the exams is available on the teacher web site.

Due to the current epidemiological situation, the written test could be substituted by an online exam (through Zoom, Moodle, Teams, etc.).

Texts

Recommended Reading:
•R. Perfetti "Circuiti elettrici" Zanichelli;
•G. Fabricatore “Elettrotecnica e Applicazioni” Liguori, Napoli (transformer and asynchronous motor);
*****
•G.Rizzoni “Elettrotecnica, Principi e Applicazioni” McGraw-Hill.

More Information

Attendance is not mandatory but highly recommended, as well as the systematic study of the program carried out during lectures, the critical analysis of the exercises in the classroom and the personal resolution of additional exercises (found in the recommended texts). During the course will be provided with copies of the slides used in class.

Questionnaire and social

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