1 M2 Electric Circuit LECTURE 7 1 LECTURE 7 INTRODUCTION TO ELECTRIC CIRCUIT Outline Introduction Circuit elements 2 Circuit elements Circuit terminologies Basic laws Time response Responses: sinusoidal vs. non-sinusoidal excitations Complex impedance and frequency response Phasors and AC powers Three-phase systems
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1
M2Electric Circuit
LECTURE 7
1
LECTURE 7
INTRODUCTION TO ELECTRIC CIRCUIT
Outline
Introduction
Circuit elements
2
Circuit elements
Circuit terminologies
Basic laws
Time response
Responses: sinusoidal vs. non-sinusoidal excitations
Complex impedance and frequency response
Phasors and AC powers Three-phase systems
2
Electricity: How they work?3
Electric Circuit4
• The battery, places a net positive charge at net positive charge at one terminal and a net negative charge on the other
• The free electrons (of negative charge) will drift toward the will drift toward the positive terminal
• The negative terminal is a “supply” of electrons
R.L. Boylestad, Introductory Circuit Analysis, 11th Ed, Prentice Hall
3
Circuit Elements
5Active Elements Passive Elements
• A dependent source is an active
Independentsources
Dependentsources
pelement in which the source quantity is controlled by another voltage or current.
• There are four different types: VCVS, CCVS, VCCS, CCCS
C.K. Alexander and M.N.O. Sadiku, Fundamentals of Electric Circuits, 5th edition, McGraw Hill
A Voltage Source6
R.L. Boylestad, Introductory Circuit Analysis, 11th Ed, Prentice Hall
http://www.splung.com/content/sid/3/page/capacitorshttp://www.area51esg.com/inductors-coils-chokes.htmlA.H. Robbins, W.C. Miller, Circuit Analysis with Devices: Theory and Practice, 3rd edition, Cengage Learning
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Circuit Terminologies11
• A branch represents a single element such as a voltage source or a resistor
• A node is the point of connection between two or more branches
• A loop is a closed path (same beginning and end nodes) with no node passed more than once
• A mesh is a loop which does not contain any other loops within it
C.K. Alexander and M.N.O. Sadiku, Fundamentals of Electric Circuits, 5th edition, McGraw Hill
The Almighty Laws: Ohm’s Law12
• George Simon Ohm
• German (Erlangen, Cologne) (1789–1854)Ge a ( a ge , Co og e) ( 789 854)
• Physicist and Mathematician
• Professor of Physics,
• University of Cologne http://www-history.mcs.st-and.ac.uk/Mathematicians/Ohm.html
• v-i relationship of a resistor
Note: the negative current and voltage result in the graph extended in the 3rd quadrant
C.K. Alexander and M.N.O. Sadiku, Fundamentals of Electric Circuits, 5th edition, McGraw Hill
R.L. Boylestad, Introductory Circuit Analysis, 11th Ed, Prentice Hall
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R.L. Boylestad, Introductory Circuit Analysis, 11th Ed, Prentice Hall
Phasor28
A phasor is a rotating line whose projection on a vertical axis can be used torepresent sinusoidally varying quantitiesaxis can be used torepresent sinusoidally varying quantities
A.H. Robbins, W.C. Miller, Circuit Analysis with Devices: Theory and Practice, 3rd edition, Cengage Learning