# 06793 - Electrotechnics

## Learning outcomes

Knowledge of basic circuit theory, methods for circuit analysis in steady-state, transient and periodic regime, three-phase systems, magnetic circuits, principle of operation of single-phase and three phase transformers.

## Course contents

Module 1

Basic concepts

Lumped circuits. Circuit elements. Voltage and current.
Power and energy. Sign conventions. Passive and active elements.
Kirchhoff's laws. Elementary network topology.
D. C. circuits
Resistors. Independent voltage and current sources. Series and parallel circuits. Current and voltage dividers. Source transformations. Millman's formulas.
Resistive two-port elements: R and G parameters, hybryd paramenters, transmission parameters, relationship between parameters, wye-delta transformation, dependent sources, ideal transformer.
Analisys methods: tableau analysis, node-voltage and mesh-current methods.
Network theoremes: Tellegen's theorem, superposition principle, Thevenin's and Norton's theorems,  non-amplification propeties, reciprocity theorem.
A.C. circuits
Capacitors. Inductors. Coupled inductors.
Phasors. Impedance and admittance. Circuit analysis in the phasor domain.
Power in AC circuits: active, reactive, and apparent power. Complex power. Effective (RMS) values. Power factor correction. Maximum power transfer.
Frequency response. Transfer function. Resonance.
Non-sinusoidal periodic regime. Introduction to Fourier series.
Transient analysis
First order RC and RL circuits. Initial conditions. Transient and steady state response. Zero input and zero state response. Second order RLC circuits. State equations.

Module 2

Three phase systems
Wye and delta connections, symmetrical and balanced systems, asymmetrical and unbalanced systems, power in three phase systems, power factor correction.
Magnetic circuits
Review of stationary magnetic field laws, ferromagnetic materials, magnetic hysteresis, reluctance and permeance, Hopkinson's law, magnetic circuit analysis, self and mutual induction.
Transformers
Operating principle, energy losses, internal equations, equivalent circuits, open-circuit and short-circuit tests, efficiency, parallel connection of transformers, three-phase transformers, special transformers.

Lecture slides are available at the following address:
http://www.die.ing.unibo.it/pers/mastri/didattica.htm

Exercises:

•  P. Ghigi, M. Martelli, F. Mastri. Esercizi di Elettrotecnica. Società Editrice Esculapio.
References:
• R. Perfetti. Circuiti elettrici. Zanichelli.
• C.K. Alexander, M.N.O. Sadiku. Circuiti elettrici. McGraw-Hill.
• G. Rizzoni. Elettrotecnica: Principi ed applicazioni. McGraw-Hill.
• G. Fabricatore, Elettrotecnica ed applicazioni, Ed. Liguori.

## Teaching methods

Theoretical lessons and numerical exercises.

## Assessment methods

The exam consists of a written test and includes a set of exercises, aiming to verify that the students understand and know how to apply the methods of circuit analysis, and a questionnaire on the theoretical aspects of the course.
During the examination is not allowed to consult books or notes, while the use of a calculator is recommended.
More information about the exam will be provided during the course and, in particular, examples resolution of exam exercises be presented during the exercitations. Exam exercises proposed in previous years and their solutions are available at the address http://www.die.ing.unibo.it/pers/mastri/didattica.htm