Lectur 1 & 2 – Basic Electrical Technology

Lectur 1 & 2 – Basic Electrical Technology


Hello everybody, today we are beginning a
course on Basic Electrical Technology. This will be roughly about 40 hours. Today I will give
you the introduction to this series of lectures which we will follow. We will not have any
technical lecture session today. Today we will just be introducing the course and the topics and
it is divided into two major parts. The first part of today’s session is the motivation;
why do you need this course and the second part is the course content meaning what is to follow,
what are the lectures to follow for the rest of this course. So I will be using the power
point presentation to introduce you to the that is the basic of electrical technology.
First let us deal with the motivation; why do you need the course. There are two points there in the motivation:
one is power generation and the other one is the load, the applications like pumps, the electric
vehicles etc. See, most of the applications require electrical power and traditionally
the electrical power is generated from the fossil fuels. Coal is used for generating major power
major amount of power in the country something like 70 to 75 percent of the energy is by
the fossil fuels, the coal thermal plants. However, for the motivation let me deviate
in this introductory session and not deal with the traditional examples of the coal thermal power
plants for the power generation, let us take examples of the renewable energy system because
today the clean energy, clean environment and renewable non-conventional energies is a simple
theme towards good living. So let us take some examples on the renewable energy methods of
power generation generating electricity and some applications. And applications also let me try to sensitise
you on the renewable systems; hybrid electric vehicles or the electric vehicles and similar
such systems. Of course there are whole lot of applications that one can look at which are
there in the literature. But just to give some sensitisation also to what is current which
is the clean energy issues we will look at some renewable energy systems and how it will fit
into our basic electrical technology course theme. One of the methods of generating electrical
power course is the hydroelectric power. There are many methods. As I said, traditionally coal
has been used fossil fuels used for generating the electrical power, thermal to the electrical
and then hydro to the electrical you have photovoltaics to the electrical, you have
the wind turbines to the electrical, you have the bio-mass methods of generation, microhydel
and so on and so forth. Now if you see in the electrical method of
generation from the hydroelectric power you will have a four bay tank, a reservoir which is
going to store up some kind of water and there is a pen stock which will lead the water to a turbine
and this turbine is connected to electric generator it will generate electricity and
then pumps it to the grid the local grid. Roughly you will see the power in kilowatts
is the order of 7 into the head into the flow of water in metre cube per second. This would
be the general scheme of an hydroelectric power generating system where do we fit in. In the
Basic Electrical Technology we will mostly be thinking about divisors and systems in this
domain that is in the electrical domain. From the prime over which is giving power it goes into
the electrical domain in the generators and then again putting it to the grid. So the domain
which we are interested in this is the electrical domain. Wind mill, wind generations; you would have
seen lot of wind mills also in our country in Southern part of India there is and also in
the Northern parts of the country, Tamil Nadu the areas of Rajasthan, Gujarat there is a
whole lot of areas where wind mill have been active. Wind mills give electric power by
virtue of the motion of air. The amount of kinetic energy which is stored in the wind is transferred
to the blades which rotate the shaft of a generator which converts it into electrical
energy then pumps it to the grid or the loads. The wind generator looks as something like
this. You see here the blades which are actually the ones which is in contact with the kinetic
moving air of the kinetic energy that is stored in the air is given to the shaft of the blade
that is the blades. Now these blades are connected to a shaft
here, it goes through a gearbox because this shaft will be rotating at different speeds and the
generator will have a shaft rotating at different speeds to have the speeds compatible you have
a gearbox and the generator which could be an induction motor or a DC generator, induction
motor acting as an induction generator or it could be an alternator all these induction
machines can be used for converting the mechanical power to the electrical power electrical output. Again the focus, the issues of interest for
us is in the electrical domain which is the scope of this course that is we will be focusing
on devices which is the electro-mechanical devices, the DC motors, DC generators, induction motor,
induction generators, synchronous motors, alternators and so on and so forth. The wind generator gives the mechanical energy
to the induction generator or any electrical generator the output of which can be converted,
rectified into DC and the DC what you get here can be inverted by means of modulation. These
are the modulation signals firing angle, these are I…….or bridges. So, by pulse width
modulation you can get out here three phase or single phase sinusoidal output voltage which can
interphase with the load or which can also interface with the mains the grid. So here again you see there is lot of electronics
and electrical items which is the electrical equipment here and the electronic and circuit
elements which are coming into focus in the picture in these kinds of applications. These
types of things will be the focus of this course which will form a part focus in the course. Another means of generation, is the photovoltaic
cell, photoelectric effect. You see here in the picture is the photovoltaic cell; it is
nothing but a pn junction. You have a P-type material the blue, the N-type material the
red, you have the you have the metallisation here, the contact here on the base and what you
see here is the glass covering which will actually cover the whole part of the top layout, top
cell, top portion of the cell. So when sunlight falls on the cell there will be lot of electrons
that gets agitated and go into the conduction band from the valence band and these free
electrons will start moving in the external wire and supply the load. Schematically you will see the lot of free
electrons get generated which go into the conduction band because it absorbs the energy
from the sunlight and they flow in the external wire to supply the various loads. Typically the solar photovoltaic applications
are of this blocked schematic nature; you get the input from the sun which is the source
and then there is a convertor here, the photovoltaic cell which converts the sun light
energy to electrical energy. So once it is in the electrical domain all these aspects all
these blocks are of interest to the analytical engineer. You have a charge controller, it
will charge up the battery and it goes through the power goes through a power conditioner which
will make it compatible to the load, here is a maximum power point tracker which is used
for tracking and obtaining the maximum energy from a given photovoltaic cell; all these are part
of electronic equipment which are basically formed from integrating the various portions of the
circuits. These are of course of importance towards circuits, its analysis, synthesis
are of importance towards which will also form a part of the course. Few examples of the photovoltaic cells; these
are how the photovoltaic cells look in the real world; each is a module as you see here mounted
on the roof top of the home. This is also a photovoltaic panel; these are
monocrystalline photovoltaic modules available in the market. These modules are available in
the wattages of around 36 watt modules or 44 watt modules that are pretty costly today. Of course
the costs are coming down. It averages somewhere around 180 rupees per watt. These are also some other photovoltaic modules.
These are polycrystalline modules. These are 44 watt modules and of course these are mounted
on top of our laboratory here to do experimentation. Again this is another array to power or to
give the electricity requirements for a small community of about fifteen homes. The photovoltaic array charges up this battery
band and from this battery band it goes through a converter to supply the various loads as
I showed or as I have told earlier in the block diagram. Another application here you will see this
is the solar challenger which is run purely solar photovoltaic cells. We will see the
photovoltaic cells are on top here on the wings. It contains something like 160000 cells at 2.7
kilowatt rating. But this is where the photovoltaic cells are
on top of the channel. Here is another application where solar photovoltaic
cells are found used. This is in the middle-east. This building is a desalination
plant which takes in the sea water, sea water contains lot of salt and it is desalinated
by reverse osmosis process. And out of this reverse osmosis process you
get two byproducts which is brine and fresh water which can be used for drinking. So the input
is the sea water and the output is fresh water in brine. Now the output’s electric power can be used
for applications like powering various home loads or various office loads which are 230 volts.
This is an inverter system where the input is photovoltaic just like your UPS system or
input of the battery this is something similar with the input as solar photovoltaic cell and the
output is 230 volts AC mains. This is another application module you see
here the photovoltaic pump which is used for pumping up water from the sump to the overhead
tank. The photovoltaic pump finds lot of useful applications and quite competitive also with
respect to the regular pumps. This is another useful application a standalone
solar power pack where input is the solar PV and output is 230 volts which can be used
to drive any home loads. We are discussing the motivation of course;
why this course, you see that lot of these products involve circuits which need to be
analysed which need to be synthesized, which needs to be designed, implemented were all the focus
or part of this course which need to be addressed. Another issue that needs to be addressed application-wise
you see; as I said there are two parts in the motivation: one is power generation;
the other portion is the load itself that is application. The environment is a serious issue today.
See, lot of pollution, you will see that way back in 1970s there were equal pollution was somewhere
here and today in the 2000s the vehicular pollution is actually increased and is the
main contributor to the air quality. As a typical graph of New Delhi which I have taken from
some of the internet webliography there is a drop here; you see, after Delhi introduced the
CNG Delhi introduced that CNG should be made compulsory mandatory for public vehicles there
has been significant drop in pollution. Then if you look at these applications you see there
is a lot of electrical and electronics which get involved just to give you it ties you to the
issues of these things and you will see that even here there is lot of scope for analytical
engineer to get involved and solve issues. You see here the picture of few electrical
electric vehicles and hybrid electric vehicles. The Reva, this is the Vikram, you see here the
Toyota Prius, the Honda Insight these are hybrid electric vehicles, this is an electric vehicle,
this is also an electric vehicle, these are also….. this is Vikram and this is Bijli
there are all electric vehicles DC motors, these are hybrid electric vehicle etc. See, if you look at the block diagram you
see where all we can contribute and probably learn as engineers learn as electrical engineers.
In electric hybrid electric vehicle there are multiple energy inputs. You see petrol is
one of the energy inputs, electricity one of the energy inputs, battery another energy input.
Now all these energy inputs are ultimately are going through the transmission to the wheels
so the petrol is driving let us say an IC engine an internal combustion engine and let us say
the output of that is connected to a generator alternator which is rectified, now it is in
the electrical domain it is now charging up the battery here or it can go through the inverter,
drive an induction motor to the wheels or conventionally traditionally it will drive
an IC engine and through a gearbox it goes to the wheels. Yeah, that could be the way
the general normal automobiles work. This schematic is a more general schematic if you look at. This schematic is called as series hybrid
where the internal combustion engine is not directly coupled to the wheels; the internal combustion
engine is coupled only to a generator which generates electrical energy and all the electrical
energy is used for either charging up the battery or driving the induction motor which
is the only thing which is connected to the wheels so it is called as series hybrid. In the case of a parallel hybrid the IC engine
that is the internal combustion engine is connected to the wheels like in conventional
traditional vehicles. There is the battery where the electrical portion of the source which
will drive an inverter an induction motor or it to drive the convertor and the DC motor and then
get connected to the wheels. So you see the wheel is driven by two power sources two park
sources; two fellows are pushing the vehicle for it is a parallel hybrid vehicle. Some of the home applications that you can
also think of you see water pumping from sump to the overhead tank, the grinders single phase
motors, you have the mixers and mixies at home where you use the universal motors they are
also electrical equipment, compressors and the refrigerators they are all electrical equipment;
so all these are containing the electrical equipment, electrical components, electromagnetic
components which are which you see in everyday life and you need to understand it,
you need to be able to analyse it, you need to be able to design that therefore we need to study
the basic electrical technology at least the first level and then later on depending on
our interest learn the advanced level courses. You also have several industrial applications
where electrical technology is very useful and probably becomes a must in many of the cases. Diesel locomotives where the diesel engine
is connected to a shaft which will drive an electrical generator like an alternator and
the output of which is converted into DC and then again an inverter motor to drive all those
things, the electric locomotives, the forklift trucks; you would have seen the forklift trucks
which are battery driven DC motors seize motors which generate high torque to lift
heavy loads. The material handling systems, rolling mills, spindle and feed drives and lathes
and CNC machines, the synchronous capacitors which are nothing but synchronous motors used for
power factor improvement and strategies; these are all electrical equipment, devices which you
will be seeing in the industrial environment that needs to be understood and studied. That is about the part on motivation meaning
there are lot of applications various application that you will see in everyday life and that
too I have given only a concise list; in fact, the list is endless. And also I have been focusing
more on the renewable applications as I told you so that we just have something different,
you will see that in the textbooks and literature that there are whole lot of applications
which will be reported where the electrical equipment becomes a major part.
In fact, in most of the cases it will be the heart of the system which needs to be understood,
analysed, designed, synthesised and so on and so forth. Now, coming to the second part of this lecture
session I would like to tell you what you will what the course will hold forth in future;
meaning what are the topics that will be covered hour by hour. The course is structured into three components.
The first part of the course will focus on electrical essentials which are really essential
for any electrical engineer to operate on the electrical technology. The second part we
will focus on electrical equipment which are the electromagnetic domains mainly transformers.
Transformers are electromagnetic devices and therefore they are called the magnetic transformers
which transform the electrical energy from one electrical energy domain to another electrical
energy domain without contact. They are in fact part and parcel of almost every electrical
system and they form the core and they are central to most of the electrical systems.
An electrical technology course without a proper understanding of the transformer is always
incomplete. So the second part will focus entirely on the transformers which is the electromagnetic
domain. The third part focuses on the electro-magneto-mechanical
domain. What it basically means is the energy flows through the electrical domain,
the magnetic domain and the mechanical domain which are the machines. The DC machines the
DC generators; and the induction machines induction generators; synchronous machines
synchronous generators alternators and so on and so forth. So the machines will have actually
all these three domains: the mechanical domain, the electrical domain and the magnetic domain
involved and in fact the remaining of the electrical systems will involve these equipment also. So the lecture 3; I consider this as lecture
2 meaning the first part the motivation as 1, the second part the course contents as 2 and the
lecture 3 which will be of course the next hour; all the lectures are 1 hour except for these
parts 1 and 2 which does not have that 1 hour constrain. The lecture 3 that is lecture 3
will deal on the topic the core topic of the electrical essential; it of course gives you
an insight of what is the source and the load and how does the energy flow from the source to
the load. When energy flows from the source to the load
there are few things that happen to it; some portion of it will get stored it will stored
as kinetic energy, it will also get stored as potential energy whichever be the domain electrical
or mechanical or any other domain and some of the portions will get dissipated in the
dissipative components like the resistor and the electrical domain they will go unavailable,
there will be some portion of the energy that may get transformed and then go to the load. So
these are the things which will………… these are the aspects of the energy flow that will come
in to being and in the circuit how does this get analysed will also be focused on. So lecture 4 and 5 again electrical essentials.
We are going to discuss on sources. what are the what are voltage sources what are current
sources and in voltage and current sources what is the AC source, what is the DC source, what
is the characteristic feature of the sources, how do you characterise them these are the
topics that need to be covered and that will be covered in lecture 4 and 5. Lecture 5 towards the end of it let us
let us discuss two important laws which of
course has come to be known as the Kirchhoff’s voltage
law and the Kirchhoff’s current law. These two laws are central to the analysis of electric
circuits any electric circuit. So a proper understanding of these two laws is very important
and that will be focused in lecture 5. In lecture 6 in the electrical essentials,
once you know how to deal with the analysis of the circuit in terms of the Kirchhoff’s voltage
law and the current law you should be you should know how to represent the electrical equipment
electrical circuit in a mathematical form. What is the mathematical representation of
the circuits; how do we how do we go about obtaining the mathematical models?
Here the state space representation gives you the dynamic model of the circuits and
equipment. We will spend time in trying to understand
the state space representation and how do we go about obtaining the mathematical model for
the various circuits; at least the methodology the courses of obtaining the mathematical model. After we are able to obtain the mathematical
model we should know what we want to do with it. We should know under what analysis that we
want to do it, how do we analyse it. So lectures 7 and 8 of the electrical essentials will focus
on analysis of the mathematical model that has been developed in these three domains: in
the time domain, in the frequency domain and in the pole-zero domain. Lecture 9 brings you the concepts of the phasor,
the vector, the space-vector, space-phasor because in the analysis of the electrical
circuits and especially when sinusoids are used the phasor diagram are used extensively to analyse
or represent the circuits pictorially and therefore it is important to understand the
concept of the phasor notation and what it means by a space phasor. Lecture 10 and 11 of the electrical essentials
we are talking of the same system which can be represented in the time domain, which can
also be represent in the pole-zero domain and how we move about these domains, what is its significant
in the other domains; these are issues that we will deal with. And lecture 12 of the electrical essential
describes the sinusoids. The sinusoidal wave shade, the sinusoidal waveform is a kind of a reference
waveform for electrical engineers it is used it is kind of ubiquitous in almost all the
electrical systems and it will appear as an input as an output, an intermediate waveform almost
everywhere and a good understanding of the sinusoidal wave shape the various parameters
its definitions, what is peak to peak, what is the RMS, what is an average and all those
things should be properly understood and the sinusoid will be defined. Then lecture 13 and 4 as I said, the electrical
circuits and equipment have a graphical representation, also you have a mathematical
representation find in the form of equations, you will also have a graphical representation
in the form of phasor diagrams. So we will spend some time to understand what is this phasor
analysis, how do we go about doing, given a circuit diagram how do we draw the phasor
diagram and try to get meaning out of it. So you will have the spatial vectors, the temporal
vectors and how do they relate to each other and things like that. Lecture 15 brings you the important concept
of power factor. Power when we draw from the source has two components: the reactive power
and the active power. The active power is the one which actually goes to the load, the reactive
power goes to setup the storage mechanisms as I said the energy flows from the source
to the destination, you will see that energy gets store in a kinetic or in electrical in the
potential form in between before it reaches the load so to setup the kinetic and the potential
energy those that are not dissipated you will see that the power that is drawn from the
source will have a reactive part which will basically be given back but it has to be drawn
and the active part which is consumed and goes off to the load. So what is the concept to
the power factor this will be discussed. What is VA, what is VAR and what is the watts. And lecture 16 of the electrical essentials
introduces to you the concept of ports the energy ports because you will be transiting from
one domain one energy domain to another energy domain like electrical domain to the magnetic
domain electrical domain to the magnetic domain to the mechanical domain. So when one transits
from one domain to another it is by means of ports and we define what is a port in any
domain. It is basically the flow of energy, flow of power at that particular port of a window.
So this will be defined and explained so that this concept will be used for explaining various
other devices. Lecture 17, 18 now enters the part II of our
course pattern course lecture pattern which is electro-magnetic domain. First was electrical
essentials that is over by chapter that is over by lecture 16. Lecture 17 starts with the
electro-magnetic domain, transformer, transformer basics, what are the essentials that is Faraday’s
laws of electro-magnetism what is it, how is the operation of the transformer so all those
things will be discussed. And then the equivalent and then the representation
of the transformer in the electrical domain as circuit form, what is the phasor
diagram all those things will be discussed in lectures 19 to 23. What is a practical transformer,
what is an ideal transformer, what is the equivalent circuit of an ideal transformer
and the practical transformer what are the differences and the various phasor diagrams
will be the topic of focus in these lectures of 19 to 23 which is the electro-magnetic domain. Lectures 24 to 29 that is 24 25 26 27 28 29
you have the electro-magneto-mechanical domain. You see we are now entering the third part
of the course pattern which is the machines. So here that is 24 to 29 we shall discuss the
machine DC generator and the DC motor where the basics is to the understanding of all the
machines. Then we follow it up with lecture 30 to 35
lectures; again we are going to revisit transformers, again we are going to revisit
the electro-magnetic domain that is the three phase circuits and three phase transformers.
Till now we have been talking on single phase but you will see the majority of the electrical
systems operate on……… lot of electrical systems operate on three phase and therefore you have
three phase circuits and three phase transformer which will be dealt with detail in these lectures
from 30 to 35. And 36 to 39 we are again discussing the electro-magneto-mechanical
domain which is the induction motor and the induction generator.
Induction motor and induction generator are very important motors; they form something like
75 to 80 percent of the prime movers of the applications world over so they are quite
important and a good understanding of these is useful both in application and design. So
induction motors and induction generators. You see the induction generators will be used in the
wind turbine generators, induction motors will be used in lot of applications including the
hybrid electric vehicles. Lecture 40 we will try to give you an insight
into the synchronous machine and the alternator, alternator or the synchronous generator based
on the concept that we have studied in the other two categories of machine the DC machine and
the induction machine we will try to extrapolate and discuss the synchronous machine and try
to get some insight to that and the lectures will conclude in lecture 40 with some typical examples
of probably what are the topics for practical and research that can be done. Now, coming to the references throughout the
course I am banking mainly on these three books for the course. Of course there are full lots
of books and then there whole lot of books course the literature that I have studied
and drawn upon from time to time. The first part that is the electrical essential
part is drawn mainly from the concepts that are from this book which is the dynamics you
see here System Dynamics A Unified Approach. authors are Dean Karnopp, Ronald Rosenberg.
This is a John Wiley publication. This actually………… the notations and symbols
here are slightly different in the sense that it is using what is known as a bond graph symbols
and methodologies. However, I have mainly drawn the concepts
from this book, I have reconverted the symbols and notations to what we electrical engineers
normally understand and use in our undergraduate courses but this is a good book to study. There is another book for the electrical essentials
“Introduction to Bond Graphs and their Applications” by Jean Thoma it is a feragument………..press. Again the notations will be quite far from
the electrical engineer notation but the concepts are similar which I have converted it to the
language of electrical engineer. Then in the case of the electro-magnetic and
the electro-magneto-mechanical equipment I have drawn upon this reference “Electrical Machines.
Drives and Power Systems” third edition, the author is Theodore Wildi. It is a Prentice
Hall publication. I have drawn lot of examples from this book
while explaining to you when we were dealing in the latter two portions of the lecture pattern
which is the electro-magnetic domain and the electro-magnetic-mechanical domain. Apart from this there are host of other books
and even the books that are referred in your undergraduate course sold by respective Universities
is also good for you to refer and study and I hope that the coming lectures will be
useful for you for your undergraduate syllabus, thank you.

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