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Electric Circuits II: Steady state AC Analysis
Diego Mej́ıa Giraldo
diego.mejia@udea.edu.co
Assistant Professor —Office 20-407
Department of Electrical Engineering — University of Antioquia
February 1, 2017
1/22
mailto:diego.mejia@udea.edu.co
Keep motivated!
I AC power is used
worldwide (at
different frequencies.)
I AC electric circuit
theory is crucial for
modeling the behavior
of electric systems.
I Essential course for
the training of every
electrical engineering
student.
2/22
Course Objectives
Main objective: Analyze steady-state sinusoidal electric circuits.
I Analyze the steady-state behavior of sinusoidal electric circuits
I Study the behavior of magnetically coupled circuits
I Compute the sinusoidal steady-state power in electric circuits.
I Analyze balanced three-phase circuits.
I Learn the basic fundamentals of residential electrical
installations.
3/22
Course Topics
I Course introduction.
I Link between Circuits I and Circuits II.
I Natural response and steady-state analysis.
I Sinusoids and Phasors.
I Sinusoids,
I phasors and complex numbers,
I phasor relationships for circuit elements, and
I impedance and admittance.
I Sinusoidal Steady-State Analysis.
I Review of nodal and mesh analysis,
I circuit theorems: superposition, source transformation,
Thevenin and Norton equivalents, and
I operational amplifier in AC circuits.
4/22
More Course Topics
I Magnetically coupled circuits.
I Mutual inductance,
I ideal transformers,
I ideal autotransformers.
I AC Power Analysis.
I Instantaneous and average power,
I maximum average power,
I effective or RMS value,
I apparent power and power factor,
I complex power, and
I power factor correction.
I Three-Phase Circuits.
I Balanced Wye-Wye, Wye-Delta, Delta-Delta, Delta-Wye
connections,
I power in a balanced system,
I symmetrical components,
I unbalanced three-phase systems.
I Residential electric circuits.
5/22
Textbooks (1)
Fundamentals of Electric Circuits
by Charles Alexander and Matthew
Sadiku
McGraw-Hill, 5 Edition, 2012.
6/22
Textbooks (2)
Electric Circuits
by James W. Nilsson and Susan Riedel
Prentice Hall, 10 Edition, 2014.
7/22
Textbooks (3)
Introduction to Electric Circuits
by James A. Svoboda and Richard C.
Dorf
Wiley, 9 Edition, 2013.
8/22
Textbooks (4)
Circuits: Engineering Concepts and
Analysis of Linear Electric Circuits
by A. Bruce Carlson
Thomson-Engineering, 1 Edition, 1999.
9/22
Grading
Date Activity Topics %
March 10 First midterm Chapters 1–2 25
April 21 Second midterm Chapters 2–3 25
May 17 Project Chapter 6 13
?? Problem sets Chapters 1–5 12
May 26 Final exam Chapters 4–5 25
10/22
Class Overview
I Class times: Wednesdays and Fridays 8:00 am – 10:00 am.
I Questions: after class or by google classroom.
I Office hours:
I Tuesdays 7:30 am – 10:00 am.
I By appointment (contact by email)
I Class material: will try to send it by email before class.
11/22
What I expect from you
I Extra work.
I Excellent math skills.
I Proper attitude in class, don’t be rude. (no sleeping, no cell
phone conversations.)
I Participation.
I Provide explanation of any results.
I Do the problem sets.
I Don’t cheat.
I Turn in homework on time.
I No extra-exams unless the vice-dean gives me the order
to do so.
I During finals, please don’t say “help me!!”.
I Read English language
12/22
What I expect from you
I Extra work.
I Excellent math skills.
I Proper attitude in class, don’t be rude. (no sleeping, no cell
phone conversations.)
I Participation.
I Provide explanation of any results.
I Do the problem sets.
I Don’t cheat.
I Turn in homework on time.
I No extra-exams unless the vice-dean gives me the order
to do so.
I During finals, please don’t say “help me!!”.
I Read English language
12/22
About me
I E.E., UTP (Pereira), 2004.
I M.S. EE, UTP, 2005.
I Ph.D., EE and (minor) Statistics, Iowa State
University, 2013.
I M.S.(C) Economics, Iowa State University, ???.
I 2004–2006: UTP (young researcher and part-time
lecturer.)
I 2006–??: Assistant prof. UdeA.
I Fulbrighter: 2008–2013.
I Research interests: Power system operations,
planning, and optimization.
I Engaged (no single at all, no married), no
children (yet).
I Hobbies: running, cycling, tennis, music (rock,
blues), photography.
13/22
Some pics!
14/22
Some pics!
14/22
Some pics!
14/22
Some pics!
14/22
Some pics!
14/22
Some pics!
14/22
Some pics!
14/22
Some pics!
14/22
Let’s start with some history
I Alternating current had first
developed in Europe due to the
work of Guillaume Duchenne
(1850s) (muscle stimulation), Ganz
Works (1870s) (three-phase
railways and tramcars), Sebastian
Ziani de Ferranti (1880s), Lucien
Gaulard, and Galileo Ferraris.
I Edison promoted DC distribution
systems. Westinghouse promoted
AC power and acquired some
patents by N. Tesla. They became
adversaries in 1880.
I DC current needed large costly
wires and forced plants to be near
the loads.
Thomas Edison
15/22
This is not a history class, but who was old friend Nikola
Tesla?
I The transformer allowed to deliver AC
power over long distances using smaller
wires at high voltage. AC power stations
could be larger, cheaper to operate.
I Tesla worked for Edison in 1882, improved
the design of Edison’s motors and
generator. By 1888, Westinghouse
decided to get Tesla’s patent on his
recently invented induction motor.
I Both helped establish AC as the primary
mode of electricity transmission and
distribution.
I AC was used for transmission of power
from Niagara Falls to Buffalo, NY.
Nikola Tesla
16/22
AC/DC
No!!!
17/22
AC/DC
No!!!
17/22
AC/DC
No!!!
17/22
AC/DC: The War of Currents
18/22
And the winner is...
“Let the future tell the truth, and
evaluate each one according to his
work and accomplishments. The
present is theirs; the future, for which
I have really worked, is mine.” –
Nikola Tesla
19/22
Sinusoidal Steady-State Analysis
I We will focus on linear circuits:
I Linear components (resistors, inductors, capacitors). Analysis
of nonlinear circuits needs the help of computational
algorithms.
I If the voltage across a linear component is doubled, so is the
current through it.
I We will focus on steady-state:
I The sinusoidal input has been applied for a long time such that
transient response has vanished.
I We will focus on sinusoidal:
I A linear circuit does not change the waveform or frequency of
a sinusoidal source.
I Power is generated as a sinusoid by rotating electrical
machines.
I Other important features of sinusoids: they can represent any
periodic function as a sum of several sinusoids with different
frequencies.
20/22
Sinusoidal Steady-State Analysis
We are interested in
I Voltage and current sources with sinusoidal wave forms,
I Effect on circuit behavior under this type of sources.
I Electricity chain (Generation, transmission, and distribution)
operates under sinusoidal steady-state conditions.
I Time-domain machinery learned in Electric Circuits I applies
to this subject.
I What is different: need to obtain the appropriate modeling
equations and deal with complex numbers.
21/22
Circuits in reality
22/22