BETA 1313

PRINCIPLES OF ELECTRIC &

ELECTRONICS

NAME: SUZIANA BINTI AHMAD

ROOM: FTK building / 1st Floor

PHONE: 06 – 2346585/ 019-6994023

E-MAIL: suziana@utem.edu.my

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Lightning- The Ultimate Power From The Almighty (Extreme Voltage & Current)

Chapter 1: Introduction to Electricity & Electronics

• Electric energy sources, Electrical system, Electric

charge, Movement of electrons and current,

• EMF and potential difference, Electrical units,

Electrical measurement instrument,

• Symbols of electrical source and components,

Electrical simple connections and applications.

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Chapter 1: Introduction to Electricity & Electronics

• Electric energy sources, Electrical system, Electric

charge, Movement of electrons and current,

• EMF and potential difference, Electrical units,

Electrical measurement instrument,

• Symbols of electrical source and components,

Electrical simple connections and applications.

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EXPERIMENTAL SETUP : The beautiful of electricity…..but…

Chapter 1 5

Electrical system

CHAPTER 1:

INTRODUCTION TO ELECTRICITY &

ELECTRONICS

ELECTRICAL SYSTEM

6

ELECTRICITY SOURCES

Transmission Line

Chapter 1 7

Control Room

Chapter 1 8

Substation (Step up/ Step down)

Chapter 1 9

Load

Chapter 1 10

Horizontal centrifugal electric water pump

Chapter 1 11

ELECTRICAL SYSTEM contd.

• Electric circuit – an interconnection of electrical elements.

• Basic electrical system consists of 4 elements:

– Source - Provide electrical energy to electrical system (i.e DCor AC source). Can be obtain from battery, generator orsocket outlet.

– Transmission system - Conduct and transfer electrical energyfrom source to load (i.e insulated wire)

– Control - Control the flow of electrical energy (i.e switch).Permits the energy to flow or else interrupts the flow.

– Load - Absorb the electrical energy and perform a giventask/purpose/work. Most domestic electrical equipmentconstitutes loads (i.e motor)

Chapter 1 12

Torch Light system

Example: Simple System

ELECTRICAL SYSTEM contd.

Chapter 1 13

Electric Charge

Chapter 1 14

• All matter of substance is made up of molecules.

• Molecules – the smallest division of a substancethat could be made without destroying theidentity or properties of the substance.

• Atoms – the smallest particle of an element thatretains the characteristics of that element.

• Most molecules is made up of multiple atoms.

– Example:

• A molecule of hydrogen gas is a combination oftwo hydrogen atoms

ELECTRIC CHARGE contd.

Chapter 1 15

• a molecule of water is a combination of two hydrogenatoms and one oxygen atom.

Hydrogen gas molecule

Water molecule

ELECTRIC CHARGE contd.

Chapter 1 16

• Atoms is made of three basic particles:

ELECTRIC CHARGE contd.

Chapter 1 17

• Normally, atoms in balance or neutral condition

(# of protons = # of electrons).

• Some atoms hold their electrons loosely especially electron that islocated at valence shell (outermost shell).

– Easy to loose electron if there is force

• The loose electrons (free electron) can be transferred into anotheratoms.

• When an electron escapes from the atom – becomes positive ion

When atom acquire an electron – becomes negative ion.

ELECTRIC CHARGE contd.

Chapter 1 18

• A substance/materials that excess of electrons (negative ion) issaid to have negative charge.

Materials with deficiency of electrons (positive ion) is said tohave positive charge.

• Electrical charge – an electrical property of matter that existsbecause of an excess or defiency of electrons.

• Charges can be measured in coulomb

1 Coulomb (C) = 6.24 x 1018 electrons

1 electron = 1.602 x 10 -19 C

• Materials with charges of opposite polarity attracted.

Materials with charges of same polarity are repelled.

ELECTRIC CHARGE contd.

Chapter 1 19

• The force that attract or repel is called electric field.

• For opposite polarity of chargers, a certain amount ofenergy must be applied to overcome the attractionforce in order to move the opposite charges a distanceapart.

• The separation will create a potential energy betweenthe chargers.

• The difference in potential energy per charge is calledthe potential difference or voltage.

ELECTRIC CHARGE contd.

Chapter 1 20

• Three categories of materials are used in electronics:

– Conductor – a material that allows the free movement of

many electrons. Good conductor of electricity. Example:

copper, iron, silver…

– Insulator – a material that have no free electrons in their

structure. Example: rubber, glass…

– Semiconductors – elements that are neither true conductors

nor insulators in their ability to permit electrons to flow.

Also can be a basis for electronic devices such as diode,

transistor.

ELECTRIC CHARGE contd.

Chapter 1 21

VOLTAGE

• To move an electron in a conductor in a particular directionrequires some work or energy transfer.

• This work can be performed by an external force or called aselectromotive force (emf).

• This emf also known as potential difference or voltage.

• Voltage (V) is the energy required to move a unit chargethrough an element, measured in volts (V).

• Voltage is a measurement of potential between two points.

Chapter 1 22

• Vab : voltage between point a and b

• It is the energy (or work) needed to move a unitcharge from a to b.

• plus (+) and minus (-) signs voltage polarity orreference direction.

VOLTAGE contd.

Chapter 1 23

• Voltage (V) is defined as energy/work per unit charge

V = W/Q

where V is voltage in volts(V), W is energy in joules (J) and Qis charge in coulombs (C).

• A voltage source is an that provides electrical energy orvoltage.

• Two types of voltage sources:

– dc voltage – a constant voltage with time. i.e. battery.

– ac voltage – a voltage that varies sinusoidally with time.

i.e. electric generator, socket outlet.

VOLTAGE contd.

Chapter 1 24

Current

• Voltage provides energy to electron, allowing them to move through a circuit.

• This movement of electrons is the current, which result in work being done in an electrical circuit.

• Consider the following:

– negative charges move from the negative terminal of battery towards the positive terminal.

Chapter 1 25

• Flow of current in metallic conductors is due to movement ofelectrons.

• However, it is universally accepted that current is the net flow ofpositive charges.

• There are two accepted conventions for the direction of electricalcurrent:

1. Electron flow direction – current is out of the negativeterminal of a voltage source, through the circuit and into thepositive terminal of the source.

2. Conventional current direction – current is out of thepositive terminal of a voltage source, through the circuit andinto the negative terminal of the source.

• The conventional current direction is used.

CURRENT contd.

Chapter 1 26

• Electric current – the time rate of change of charge, measured in amperes (A).

I = Q / t

where I is current in amperes(A), Q is charge in coulombs (C) and t is time in seconds.

• Generally, have two types of current:

– direct current (dc) – a current that remains constant with

time.

– alternating current (ac) – a current that varies sinusoidally

with time.

CURRENT contd.

Chapter 1 27

POWER & ENERGY

• Power – a certain amount of energy (W) used in a certainlength of time (t),

• Denoted by P.

where P = power in watts (W)

W = energy in joules (J)

t = time in seconds (s)

V = voltage in volts (V)

I = current in amperes (A)

WP

t= P VI=

Chapter 1 28

• In electric circuit, power can either be absorbed or

supplied by an element – the product of voltage across

the element and current through it.

• Positive power – power is absorb by the element.

• Negative power – power is supplied by the element.

• How to identify positive and negative power? Based on

the direction of current flow and voltage polarity.

P VI= +

POWER & ENERGY contd.

P VI= −

P VI=

Chapter 1 29

POWER & ENERGY contd.

Note: focus on the direction of current entering an element. If enter at:•+ve terminal – power absorbed •-ve terminal – power supplied

Chapter 1 30

• Law of conservation of energy – energy cannot be

created or destroyed, but can change its form.

• Therefore, the algebraic sum of power in a circuit, at any

instant of time, must be zero.

• The total power supplied to the circuit must equal to the

total power absorbed.

0P =∑

POWER & ENERGY contd.

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supplied absorbedP P=∑ ∑

Chapter 1 31

• Energy – the capacity to do work, measured in joules (J).

POWER & ENERGY contd.

0 0

t t

t tw p dt vi dt= =∫ ∫

Chapter 1 32

CIRCUIT ELEMENTS

• Element – basic building block of a circuit or electricalcomponents of an electrical circuit.

• Electric circuit – an interconnection of electricalelements.

• Circuit analysis – process of determining voltages across(or the currents through) the elements of the circuit.

• Two types of elements in electrical circuits:– Active elements

– Passive elements

Chapter 1 33

• Active elements – elements capable ofgenerating electrical energy i.e. voltage source& current source.

• Passive elements – elements not capable ofgenerating electrical energy i.e. resistor,capacitor and inductors.

• Voltage & current source deliver power to theelectrical circuit.

• Two kinds of sources:– Independent sources.

– Dependent sources.

CIRCUIT ELEMENTS contd.

Chapter 1 34

• Ideal independent source – an activeelements that provides a specified voltageor current that is completely independentof other circuit elements.

CIRCUIT ELEMENTS contd.

Chapter 1 35

• Ideal dependent (or controlled) source – an activeelement in which the source quantity is controlled byanother voltage or current.

• Four types of dependent source:– A voltage-controlled voltage source (VCVS)

– A current-controlled voltage source (CCVS)

– A voltage-controlled current source (VCCS)

– A current-controlled current source (CCCS)

CIRCUIT ELEMENTS contd.

Chapter 1 36

• Consider the following:

– The CCVS is depends on i.

– Value = 10i V

CIRCUIT ELEMENTS contd.

Chapter 1 37

SYSTEMS OF UNITS

• Basic SI (International System of Units) units:

Quantity Unit Symbol

Charge (q) coulomb C

Energy (E) joule J

Power (P) watt W

Voltage (V) volt V

Current (I) ampere A

Resistance (R) ohm Ω

Induction (L) Henry H

Capacitance (C) farad F

Chapter 1 38

• The SI prefixes:

Power of 10 Prefix Symbol

+18 Exa E

+15 Peta P

+12 Tera T

+9 Giga G

+6 mega M

+3 kilo k

+2 hecto h

+1 deka D

- 1 deci d

- 2 centi c

- 3 milli m

- 6 micro µ

- 9 nano n

- 12 pico p

- 15 femto f

- 18 atto a

SYSTEMS OF UNITS contd.

Chapter 1 39

There are 5 branches.

NODES, BRANCHES & LOOPS

• Branch – represents a single elements such as voltage

source or a resistor.

Number of branches?Named the branches?

10 V voltage source, 2 A current source and three resistors

5 branches. There are the 10 V voltage source, 2 A current source and three resistors.

Chapter 1 40

• Node – a point of connection between two or more

branches.

NODES, BRANCHES & LOOPS contd.

Chapter 1 41

• Indicated by a dot.

• A node where the point of connection between three or

more branches is called essential node.

NODES, BRANCHES & LOOPS contd.

Chapter 1 42

=

NODES, BRANCHES & LOOPS contd.

Chapter 1 43

• Loop – any closed path in a circuit.

• A loop is a closed path formed by starting at a node,

passing through a set of nodes and returning to the

starting node without passing through any node more

than once.

NODES, BRANCHES & LOOPS contd.

Chapter 1 44

BASIC CONNECTIONS

• Two types of connections:

– Series

– Parallel

• Series connection – two elements are joint at a node and no

other element is connected to that node.

• Elements in series carry the same current.

Chapter 1 45

The series connection are:

• A & B

• D, E & F

BASIC CONNECTIONS contd.

Chapter 1 46

• Parallel – elements that are connected to the

same pair of terminals.

• Elements in parallel have the same voltage

across them

BASIC CONNECTIONS contd.

Chapter 1 47

Parallel connections:

• C &D

• G, H & J

Series connection – A & B

BASIC CONNECTIONS contd.

Chapter 1 48

EXAMPLE 1

Calculate the power absorbed or supplied by each

element of the above figure.

Chapter 1 49

• p1 = 20(5) = 100 W– Since the current leaves the positive terminal thus,

p1 = -100 W

• p2 = 12(5) = 60 W

– The current enters the positive terminal

• p3 = 8(6) = 48 W– The current enters the positive terminal

• p4 = 8(0.2I) = 8(0.2 x 5) = 8 W– Since the current leaves the positive terminal thus,

p4 = -8W

EXAMPLE 1 contd.

Chapter 1 50

• Algebraic sum of power in the circuit

p1 + p2 + p3 + p4 = -100 + 60 + 48 – 8 = 0

EXAMPLE 1 contd.

Chapter 1 51

EXAMPLE 2

Calculate the power absorbed or supplied by each

element of the above figure.

Chapter 1 52

• p1 = -40 W

• p2 = 16 W

• p3 = 9 W

• p4 = 15 W

• p1 + p2 + p3 + p4 = -40 + 16 + 9 – 15 = 0

EXAMPLE 2 contd.

Chapter 1 53

EXAMPLE 3

Determine the number of branches and nodes. Identify which elements are in series and parallel.

Chapter 1 54

• Since there are 4 elements, the circuit has 4 branches: 10 V, 5 Ω, 6 Ω and 2 A.

• Has 3 nodes.

• Series connection: 5 Ω resistor with 10 V voltage source.

• Parallel connection: 6 Ω resistor with 2 A current source.

EXAMPLE 3 contd.

Chapter 1 55

EXAMPLE 4

Determine the number of branches and nodes.

Identify which elements are in series and parallel.

Chapter 1 56

• Since there are 5 elements, the circuit has 5 branches

• Has 3 nodes.

• Parallel connection: – 1 Ω & 2 Ω resistors.

– 4 Ω resistor with 10 V source.

EXAMPLE 4 contd.

Chapter 1 57

RECALL

• Dc – current that remains constant with time.

• Dc voltage – voltage that remains constant with time.

• Ac – current that varies sinusoidally with time.

• Ac voltage – voltage that varies sinusoidally with time.