tess.pdf

Kurdistan Region - IRAQ Ministry of Higher Education & Scientific Research Koya University Faculty of Engineering Petroleum Engineering Department

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COURSE BOOKS

Electrical Engineering Technology

Second Stage

Academic Year: 2013-2014

Assistant Teacher: Caroline Daniel

E-mail: [email protected]


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Course Name Electrical Engineering Technology

Code PETE 208

Academic Year 2013-2014

Teacher in Charge Assistant Lecturer, Caroline Y. Daniel

Faculty / School /

Department Faculty of Engineering / petroleum Dept.

Contact details

Email: [email protected]

Class website:

https://sites.google.com/a/koyauniversity.org

Coordinator Name Dr.Nawzat Rashed Ismaeel

Coordinator Contact

Details [email protected]

Time Table

Grading

The students are required to do two closed book exams two times during

the academic year

besides the laboratory assignment;

1st Mid-term Exam: 30%

2nd

Mid-term Exam: 30%

Final Exam: 40%

Course Overview

Classes Wednesday : 01:30 3:30 PM ( Practical) Monday: 08:30 10:30 PM ( Theory)

Electrical Engineering is introduced to understand the fundamentals of

electrical engineering. The aim of subject is to make familiar the

students with the basic terms, laws and theorems related to electrical

engineering. The subject also gives the little idea about electrical power

system, circuit theory and instrumentation. The subject also deals with

the electrical machines like transformer, motor and generator.


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Course Reading List:

1. Electricity, Priciples and Applications, Fowler, 6th Edition, copy

right 2003.

2. Principles of Electric Circuits, Floyd, 8th Edition, copy right 2003.

3. Electrical Engineering, U. A. Bakshi and V. U. Bakshi, copy right

2008.

4. Basic Electrical Engineering, Pankaj Swarnkar, copy right 2009.

Weekly Course Outlines (3 hrs weekly)

Lecture Topic

1 Introduction, basic electrical quantities, elements and definitions.

2 Electrical Engineering Materials (conductors, semiconductors and insulators).

3 Resistors (resistance and resistivity), types of resistors, Ohms law, Temp effects.

4 DC power electrical cells and batteries (types and construction).

5 Electrical Energy, Power, and Efficiency.

6 Series circuits and KVL. Parallel circuits and KCL.

7 Star-Delta conversion, Electrical networks simplification.

8 Electrical networks simplification (cont.).

9 Network theorems (Mesh analysis, Nodal analysis).

10 Network theorems (Superposition theorem).

11 Network theorems (Thevenins theorem, Nortons theorem).

12 Network theorems (Maximum power transfer theorem).

13 Capacitors and capacitance, Capacitors in series and in parallel.

14 Inductors and inductance, Inductors in series and in parallel.

15 AC fundamentals, Resistor, Capacitor and inductor in AC circuits.

16 Series AC circuits, Parallel AC circuits.

17 DC machines principles, construction and applications (DC generators).

18 DC machines principles, construction and applications (DC motors).

19 AC machines principles, construction and applications (AC generators).

20 AC machines principles, construction and applications (AC motors).

21 AC machines principles, construction and applications (transformers).

22 3-Phase principles.

23 3-Phase machines. (Introduction). 24 Electrical power transmission and distribution, Average power, Power Factor.

25 Electrical Cables and wires (types and sizes), Circuit breakers and Relays.

26 Industrial applications of electric machines in petroleum engineering

27 Industrial applications of electric machines in petroleum engineering (cont.)

28 Introduction of Renewable energy.


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1.Basic Definition:

Goal of lecture: Through this subject the student recognize the meaning

of the electrical engineering elements and theirs symbols.

Energy: is the capacity of doing any work, the unit of Energy is Joule (J).

Current: Electric current is defined as the time rate of net motion of

electric charge in any conductor and its unit is Ampere (A).

Potential: the work done to transfer unit positive charge from infinity to

any point in electric field and its unit is Volt (v).

Power: is defined as the time rate of change of energy.

Resistance: is the circuit constant which was introduced in 1826 by Ohm.

According to Ohms Law, the voltage across any branch is directly

proportional to the current passing through it and its unit is Ohm ().

2. Ohms law of linear electrical resistors:

Ohms Law: this is the most fundamental law which was given by

ohm in 1825. According to this law, voltage in directly proportional

to current across any element when the physical conditions remain

constant. So the potential difference across any resistance is


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directly proportional to the current passing in it on condition

that the temperature is kept constant.

vI

v=RI

Current Divider:

Voltage Divider:

For D.C

V I

V=RI

For A.C

V I


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V=Zi

Z=R+jX

3. Resistors Connections:

1.series connection:

Req=R1+R2

2. parallel connection:

Req=

Transfer and :

:

R1

R2 R3 R4 R5

R6


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:

4. Electrical networks theorems: 4.1 Kirchhoffs Law:


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1. First law (current law): the algebraic sum of the current at any

node is equal to zero.

2. Second law (potential law): the algebraic sum of the potential

difference around any close loop equal to zero.

Example: find the currents in the circuit shown by kirchoffs law.

30 I1+10I2-100 = 0

3I1+I2 = 10 (1)

20(I1-I2)-50-10I2=0

2I1-3I2=5 (2)

I1 = 3.18 A

I2 = 0.46 A

4.2 Mesh (Maxwell) Current:

Suppose current to all loops.

Add the voltages of any loop equal to zero.

I1 I1-I2

I2


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Example. Find the current in each resistor using mesh method.

10 I1+20(I1 I2) 40 = 0

3I1 2I2 = 10 (1)

30I2+70+40+20 (I2 I1) = 0

5I2 2I1 = -11 (2)

4.3 Nodal Analysis: in this method we select nodes and one

reference (ground) node. Since voltage is not the absolute quantity and

is always defined with respect to some reference or ground so we have

to choose one node as the reference whose voltage is zero.

Example. Find the current in each resistor using nodal analysis.

I1 I2

V1


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V1=42.85 volt

4.4 Super position Theorem: super position theorem states that in

any linear, active, bilateral network, having more than one source

response across any element is the sum of response obtained by each

source considered separately and all other sources are replaced by their

internal resistances.


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Example. Find the current in each resistance by using super position

theorem.

Effect of 2A:

I1=2A

Effect of 60 volt:

I10=2A

I20=2A

I40=2+0=2A

I10=2-1.333=0.666A

I20=

I1 I3

I2


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4.5 Thevenin Theorem: this theorem was proposed to solve the

complicated networks in 1883 by the French telegraph engineer Leon

Thevenin.

Any linear, active, bilateral complicated network across its load terminals

can replaced by single voltage source and one series resistance.

Example. Find the current in 60 ohm by using thevenin.

Vth=40*4=160 volt

Rth=30+10 // 40 =38ohm

4.6 Norton Theorem: the dual of thevenin theorem was given by E.

L. Norton of the Bell Telephone Laboratories. According to Norton

theorem: any linear, active, bilateral complicated network across its load

terminals can be replaced by single current source and one parallel

resistance.


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Example. Find the current in 5ohm using Norton method.

Effect of 100 volt:

Rth=(15 // 30) // 60=8.57 ohm

5.Capacitors and Inductance:

5.1 Capacitors: Example:

For the circuit in the figure:

1- Find the total capacitance.


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2- Determine the charge on each plate.

3- Find the voltage across each capacitor.

1- 1/CT = 1/C1+1/C2+1/C3 = 1/200x10-6

+1/50x10-6

+1/10x10-

6=0.125x10

-6 CT=1/0.125x10

-6=8F

2- QT =Q1 =Q2 =Q3 =CTE = 8x10-6x60=480F

3- V1=Q1/C1=480x10-6

/200x10-6

=2.4V V2= Q2/C2=480x10-6

/50x10-

6=9.6V V3= Q3/C3=480x10

-6/10x10

-6=48V and E= V1+ V2+ V3

=2.4+9.6+48 =60V.

5.2 Inductance: Any device relying on magnetism or magnetic fields to operate is a form of inductor. Motors, generators, transformers, and

coils are inductors. The use of an inductor in a circuit can cause current

and voltage to become out-of-phase and inefficient unless corrected.

In an inductive AC circuit, the current is continually changing and is continuously

inducing an EMF. Because this EMF opposes the continuous change in the flowing

current, its effect is measured in ohms. This opposition of the inductance to the flow

of an alternating current is called inductive reactance (XL). Equation below is the

mathematical representation of the current flowing in a circuit that contains only

inductive reactance.


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where

I = effective current (A)

XL = inductive reactance () E = effective voltage across the reactance (V)

The value of XL in any circuit is dependent on the inductance of the circuit and on the

rate at which the current is changing through the circuit. This rate of change depends

on the frequency of the applied voltage. Equation below is the mathematical

representation for XL.

= ~3.14 f = frequency (Hertz)

L = inductance (Henries)

6. AC fundamentals: No circuit is without some resistance, whether desired or not. Resistive

and reactive components in an AC circuit oppose current flow. The total

opposition to current flow in a circuit depends on its resistance, its

reactance, and the phase relationships between them. Impedance is

defined as the total opposition to current flow in a circuit. Equation below

is the mathematical representation for the magnitude of impedance in an

AC circuit.

where

Z = impedance ()

R = resistance ()

X = net reactance ()


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The current through a certain resistance is always in phase with the

applied voltage. Resistance is shown on the zero axis. The current

through an inductor lags applied voltage by 90; inductive reactance is

shown along the 90 axis. Current through a capacitor leads applied

voltage by 90; capacitive reactance is shown along the -90 axis. Net

reactance in an AC circuit is the difference between inductive and

capacitive reactance. Equation below is the mathematical representation

for the calculation of net reactance when XL is greater than XC.

where

X = net reactance ()

XL = inductive reactance ()

XC = capacitive reactance ()

7. series AC circuits :

Impedance is the resultant of phasor addition of R and XL. The symbol

for impedance is Z. Impedance is the total opposition to the flow of

current and is expressed in ohms. below is the mathematical

representation of the impedance in an RL circuit.

Example: A 50 XC and a 60 resistance are in series across a 110V

source Calculate the impedance.


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8. parallel AC circuits:

Total current in a parallel R-C-L circuit is equal to the square root of the

sum of the squares of the current flows through the resistance, inductive

reactance, and capacitive reactance branches of the circuit. Equations

below are the mathematical representations of total current in a parallel

R-C-L circuit. Because the difference between IL and IC is squared, the

order in which the quantities are subtracted does not affect the answer.

where

IT = total current (A)

IR = current through resistance leg of circuit (A)

IC = current through capacitive reactance leg of circuit (A)

IL = current through inductive reactance leg of circuit (A)

Example: A 200 resistor, a 100 XL, and an 80 XC are placed in

parallel across a


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120V AC source .Find: (1) the branch currents, (2) the total current,

and (3) the impedance.


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9. DC machines fundamentals:

9.1 DC Generator:

DC generators are widely used to produce a DC voltage. The amount of

voltage produced depends on a variety of factors.

There are three conditions necessary to induce a voltage into a conductor:

1. A magnetic field

2. A conductor

3. Relative motion between the two

A DC generator provides these three conditions to produce a DC voltage

output. A basic DC generator has four basic parts: (1) a magnetic field;

(2) a single conductor, or loop; -(3) a commutator; and (4) brushes

(Figure 7-1). The magnetic field may be supplied by either a permanent

magnet or an electromagnet. For now, we will use a permanent magnet to

describe a basic DC generator.

9.2 DC Motors:

DC motors are widely used to drive various equipment. The speed and

torque produced in a DC motor depends on a variety of factors. There are

two conditions which are necessary to produce a force on a conductor.

The conductor must be carrying current. The conductor must be within a


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magnetic field. When these two conditions exist, a force will be applied

to the conductor, which will attempt to move the conductor in a direction

perpendicular to the magnetic field. This is the basic theory by which all

DC motors operate.

10. AC machines fundamentals:

10.1AC Motors:

AC motors are widely used to drive machinery for a wide variety of

applications. To understand how these motors operate, a knowledge of

the basic theory of operation of AC motors is necessary.

The principle of operation for all AC motors relies on the interaction of a

revolving magnetic field created in the stator by AC current, with an

opposing magnetic field either induced on the rotor or provided by a

separate DC current source. The resulting interaction produces usable

torque, which can be coupled to desired loads throughout the facility in a

convenient manner. Prior to the discussion of specific types of AC

motors, some common terms and principles must be introduced.

10.2Induction Motors:

Various types of AC motors are used for specific applications. By

matching the type of motor to the appropriate application, increased

equipment performance can be obtained.


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Previous explanations of the operation of an AC motor dealt with

induction motors. The induction motor is the most commonly used AC

motor in industrial applications because of its simplicity, rugged

construction, and relatively low manufacturing costs. The reason that the

induction motor has these characteristics is because the rotor is a self-

contained unit, with no external connections. This type of motor derives

its name from the fact that AC currents are induced into the rotor by a

rotating magnetic field.

10.3Transformer:

Transformers are used extensively for AC power transmissions and for

various control and indication circuits. Knowledge of the basic theory of

how these components operate is necessary to understand the role

transformers play in todays nuclear facilities.

11. 3 phase analysis:

A three- -phase

balanced

generator that produces three separate and equal voltages, each of which

is 120 out of phase with the other voltages.


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Three-phase equipment (motors, transformers, etc.) weighs less than

single-phase equipment of the same power rating. They have a wide

range of voltages and can be used for single-phase loads. Three-phase

equipment is smaller in size, weighs less, and is more efficient than

single-phase equipment.

Three-phase systems can be connected in two different ways. If the three

common ends of each phase are connected at a common point and the

other three ends are connected to a 3line, it is called a wye, or Y-. If the

three phases are connected in series to form a closed loop, it is called a

delta, or -, connection.

12. Instruments:

DArsonval - A DC moving coil movement where the moving coil is

suspended between the poles of a permanent magnet restrained by helical

springs, and the measured current flowing through the moving coil

produces a torque on the attached pointer proportional to the current.


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Electrodynamometer - The moving coil and attached pointer are

suspended between and connected in series with the two stationary field

coils so that the same current flows through each. A measured current

flowing through the three coils in either direction causes a magnetic

repulsion between the field coils and the moving coil. The magnetic

repulsion exerts a force against the spring and provides a measurement of

either DC or AC current.

Moving iron vane - The moving iron vane meter operates on the

principle of magnetic repulsion between like poles. The measured current

flows through a field coil which induces a like magnetic field into a fixed

and moving vane causing the moving vane to deflect a pointer in

proportion to the current or voltage applied to the coil.

Diodes:

Diodes are essentially one-way current gates

Symbolized by:

Current vs. voltage graphs:

Diodes are made of semiconductors (usually silicon)

Essentially a stack of p-doped and n-doped silicon to form a p-n

junction

Transistors are n-p-n or p-n-p arrangements of semiconductors


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Transistors:

Renewable energy

Wind power:

Airflows can be used to run wind turbines. Modern wind turbines range

from around 600 kW to 5 MW of rated power, although turbines with

rated output of 1.53 MW have become the most common for commercial use; the power output of a turbine is a function of the cube of

the wind speed, so as wind speed increases, power output increases

dramatically. Areas where winds are stronger and more constant, such as

offshore and high altitude sites, are preferred locations for wind farms.

Typical capacity factors are 20-40%, with values at the upper end of the

range in particularly favourable sites.

Globally, the long-term technical potential of wind energy is believed to

be five times total current global energy production, or 40 times current

electricity demand. This could require wind turbines to be installed over


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large areas, particularly in areas of higher wind resources. Offshore

resources experience average wind speeds of ~90% greater than that of

land, so offshore resources could contribute substantially more energy.

Solar Energy:

Solar energy is the energy derived from the sun through the form of solar

radiation. Solar powered electrical generation relies on photovoltaics and

heat engines. A partial list of other solar applications includes space

heating and cooling through solar architecture, day lighting, solar hot

water, solar cooking, and high temperature process heat for industrial

purposes.

Solar technologies are broadly characterized as either passive solar or

active solar depending on the way they capture, convert and distribute

solar energy. Active solar techniques include the use of photovoltaic

panels and solar thermal collectors to harness the energy. Passive solar

techniques include orienting a building to the Sun, selecting materials

with favorable thermal mass or light dispersing properties, and designing

spaces that naturally circulate air.

Geothermal energy:

Geothermal energy is energy obtained by trapping the heat of the earth

itself, both from kilometers deep into the Earth's crust in volcanically

active locations of the globe or from shallow depths, as in geothermal

heat pumps in most locations of the planet. It is expensive to build a

power station but operating costs are low resulting in low energy costs for

suitable sites. Ultimately, this energy derives from heat in the Earth's

core.


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