06793 - Electrotechnics

Learning outcomes

At the end of the course, the student will have knowledge of the fundamental properties of electrical circuits, the main methodologies of circuit analysis, the basic principles on which the transmission and distribution of electrical energy are based, magnetic circuits, the basic laws of electrical machines and the operating principles of the transformer.

Course contents

Definition of fundamental quantities and laws

Definition of circuit theory and electrical circuit, the definition of voltage, current, power, and energy. Kirchhoff's laws. Basic circuit elements: resistor and idea sources. Ohm's law, power, and energy in resistive networks.

Direct current circuits

Analysis of resistive circuits with one generator. Series and parallel connection, voltage divider and current divider. Solution of circuits by simplification. Circuit properties and methods of analysis: superposition of effects, Millman's theorem, Thevenin's and Norton's theorems, nodal analysis. Four-terminal circuit elements: dependent sources, ideal transformer. Analysis of circuits with four terminal elements. Principle of maximum power transfer

Transients

Introduction to transient circuits, the definition of basic circuit elements: capacitor, inductor, and coupled inductors. First-order circuits. Study of first-order transients RL and RC using equations of state

Sinusoidal steady-state

Definition of sinusoidal steady-state, periodic quantities, sinusoidal quantities, operations between isofrequential sinusoidal quantities. Symbolic method: phasors. Operations with phasors: a reminder of the algebra of complex numbers; properties of phasors. Kirchhoff's laws in symbolic form, constitutive laws of electrical components in symbolic form: impedance and generalized Ohm's law. The generalization of principles and theorems in the phasor domain, phasor diagram.

Power in sinusoidal steady-state circuits: instantaneous power, active and reactive power, complex and apparent power. Maximum power transfer in sinusoidal steady-state. Boucherot's theorem Power factor correction of single-phase inductive loads.

Three-phase circuits

Origins of three-phase systems. Definitions: symmetrical system, balanced system, phase voltages, line-to-line voltages, three-wire system, four-wire system. Star connection and delta connection; three-phase loads in series and parallel. Equivalent single-phase circuit. Three-phase power factor correction: star and delta connection of power factor correction capacitors. Connection of single-phase loads.

Recalls of magnetostatics

Diamagnetic, paramagnetic and ferromagnetic materials. Magnetic circuits with lumped parameters; Hopkinson's law.

The transformer

Principle of operation of single-phase transformer; ideal transformer; hysteresis and eddy current losses; transformer equivalent circuit.; three-phase transformer.

Elements of electrical systems

Scheme of the electrical system. Comparison of single and three-phase alternating current transmission lines. Protection against electrical fault: overvoltage and overcurrent; fuse, magnetic, thermal, and differential relay.

Readings/Bibliography

Suggested books:

• “Elettrotecnica: elementi di teoria ed esercizi”, M. Repetto e S. Leva, Città studi edizioni
  
  
• “Electric circuits”, Charles K. Alexander, Matthew N. O. Sadiku, McGraw-Hill Education

Teaching methods

The course consists of lectures and exercises. Handouts and compendium material will be provided by the lecturer and uploaded on the course webpage.

Assessment methods

A final examination is held to assess the acquisition of the expected knowledge and skills in a written test lasting about 2 hours.

The written test normally consists of a series of multiple choice questions and 2 exercises in which the student is asked to study electrical or magnetic circuits and multiple choice questions.

A pass mark will be awarded to students who demonstrate mastery and operational ability in relation to the key concepts covered in the course, and in particular in relation to the fundamental concepts of circuit theory and the ability to solve electrical and magnetic circuits. A higher mark will be awarded to students who are able to use and link together all the content of the course. Failure to pass the examination may be due to insufficient knowledge of the key concepts.

Teaching tools

As a useful tool for learning and testing exercises, the use of the SpicePyBot tool on Telegram is proposed.

Documentation of the tool can be accessed at the following link:

https://github.com/giaccone/SpicePyBot

Office hours

See the website of Vincenzo Cirimele