INTRODUCTION TO ELECTRICAL ENGINEERING Module 1

INTRODUCTION TO ELECTRICAL
ENGINEERING
Course code: BESCK204B
DEPT.OF ECE,MITE MOODBIDRI

Course Syllabus
M1. Introduction to energy sources, Power generation, DC circuits
M2. AC fundamentals, three phase circuits
M3. DC generator, DC motor
M4. Transformers, Three Phase Induction Motors
M5. Domestic wiring, Electricity Bill, Equipment Safety measures,
Personal Safety measures

Module-1
Introduction: Conventional and non-conventional energy resources;
General structure of electrical power systems using single line diagram
approach.
Power Generation: Hydel, Nuclear, Solar & wind power generation
(Block Diagram approach).
DC Circuits: Ohm’s Law and its limitations. KCL & KVL, series,
parallel, series-parallel circuits. Simple Numerical.

Module-2
A.C. Fundamentals:
Equation of AC Voltage and current, waveform, time period, frequency,
amplitude, phase, phase difference, average value, RMS value, form factor,
peak factor. (only definitions)
Voltage and current relationship with phasor diagrams in R, L, and C
circuits. Concept of Impedance.
Analysis of R-L, R-C, R-L-C Series circuits. Active power, reactive power
and apparent power. Concept of power factor. (Simple Numerical).
Three Phase Circuits:
Generation of Three phase AC quantity, advantages and limitations; star and
delta connection, relationship between line and phase quantities (excluding
proof)

Module-3
DC Machines:
DC Generator: Principle of operation, constructional details, induced
emf expression, types of generators. Relation between induced emf and
terminal voltage. Simple numerical.
DC Motor: Principle of operation, back emf and its significance. Torque
equation, types of motors, characteristics and speed control (armature &
field) of DC motors (series & shunt only). Applications of DC motors.
Simple numerical.

Module-4
Transformers: Necessity of transformer, principle of operation, Types
and construction of single phase transformers, EMF equation, losses,
variation of losses with respect to load. Efficiency and simple numerical.
Three-phase induction Motors: Concept of rotating magnetic field,
Principle of operation, constructional features of motor, types – squirrel
cage and wound rotor. Slip and its significance, simple numerical.

Module-5
Domestic Wiring: Requirements, Types of wiring: casing, capping. Two
way and three way control of load.
Electricity Bill: Power rating of household appliances including air
conditioners, PCs, laptops, printers, etc. Definition of “unit” used for
consumption of electrical energy, two-part electricity tariff, calculation of
electricity bill for domestic consumers.
Equipment Safety measures: Working principle of Fuse and Miniature
circuit breaker (MCB), merits and demerits.
Personal safety measures: Electric Shock, Earthing and its types,
Safety Precautions to avoid shock.

INTRODUCTION TO ELECTRICAL
ENGINEERING
Course code: BESCK204B
COURSE OUTCOMES
CO1
Discuss the power generation concepts and analyse the behaviour of DC
circuits using Ohms law and Kirchhoff’s Laws.
CO2
Infer the phasor relationship between voltage and current in series and
parallel combination of single-phase R-L-C circuit. Identify the relationship
between line and phase quantities in a three-phase AC circuit.
CO3
Outline the relation between terminal voltage, load voltage, flux linkage,
torque and speed in DC Motors and Generators.
CO4
Illustrate the concept of transformers in transmission and distribution of
electric power. Explain the construction and working principle of induction
motor.
CO5
Demonstrate the electric wiring, calculate electricity bill and recognize the
need for electrical safety measures.

Suggested Learning Resources
Text Books:
1.Basic Electrical Engineering by D C Kulshreshtha, Tata McGraw Hill, First Edition
2019.
2.A text book of Electrical Technology by B.L. Theraja, S Chand and Company,
reprint edition 2014.
Reference Books:
1. Basic Electrical Engineering, D. P. Kothari and I. J. Nagrath, Tata McGraw Hill 4th
edition, 2019.
2.Principles of Electrical Engineering & Electronics by V. K. Mehta, Rohit Mehta, S.
Chand and Company Publications, 2nd edition, 2015.
3rd
3. Fundamentals of Electrical Engineering by Rajendra Prasad, PHI, edition,
2014.

Text Books

Module 1
Introduction, Power generation,
DC circuits

INTRODUCTION

Contents
 Introduction
Conventional and non-conventional energy
resources
General structure of electrical power
systems using single line diagram approach

Introduction
Electrical energy is the most popular form of the energy. Some features
of electrical energy are as follows:
 Electric energy is most convenient and efficient for production of light
and rotational mechanical motion.
 It can be transported easily and efficiently over long distance from
production site to a large number of points of use
 Electric energy must be generated centrally and instantly transported
to vast geographical regions within and beyond national boundaries.
 It cannot be stored in large quantities, except in batteries for limited
use.

Sources of generating electricity
Conventional
methods
Thermal
Hydro-
electric
Non-
conventional
methods
Wind
power
Fuel cells
Photo
voltaic
cells
Tidal
Geo
thermal

Thermal
• Thermal energy (from
fossil fuels like coal) or
Nuclear Energy used for
producing steam for
turbines which drive
the alternators (=
rotating a.c.
generators).
Hydro-electric
• Potential of water
stored at higher
altitudes is utilized as it
is passed through
water-turbines which
drive the alternators.
(a) Conventional methods

(i) Wind power:
• High velocities of wind
(in some areas) are
utilized in driving wind
turbines coupled to
alternators.
(ii) Fuel cells:
• These are devices
which convert
chemical energy of a
fuel into electrical
energy by means of
electrochemical
reactions. These cells
are pollution-free and
noise-free. It is yet to
become popular for
bulk-power
generation.
(iii) Photo voltaic cells:
• These directly convert
solar energy into
electrical energy
through a chemical
action taking place in
solar cells. These cells
operate on the photo-
voltaic effect (here an
emf is developed
during the absorption
of ionizing radiation
from Sun).
(b) Non-conventional methods

General structure of a electrical power
system using line diagram approach
 A one - line diagram of a power system shows the main
connections and arrangement of different components in three
phase power systems
 These line diagrams use symbols for generators, motors,
transformers and loads.
Example: Circuit breakers are represented as rectangular blocks.
 Any particular component may or may not be shown depending
on the information required in a system study, e.g. circuit
breakers need not be shown in a load flow study but are a must
for a protection study.

General structure of a electrical power
system using line diagram approach
Fig 1.1 Line diagram of a simple electrical power
system

Indicates a generator with Y (Star)
connection grounded through resistance
and inductance
Indicates a transformer with star-delta
connection, with star connection directly
grounded. Square blocks indicate the circuit
breaker.
General structure of a electrical power system
using line diagram approach

POWER TRANSMISSION SYSTEM

1. Generating Station: Electric power is commonly (or
usually) generated at 11 kV in generating stations in India
and Europe.
2. Primary Transmission: This generating voltage is then
stepped up to 132kV, 220kV, 400kV or 765kV etc.
Stepping up the voltage level depends upon the distance
at which power is to be transmitted. Longer the distance,
higher will be the voltage level. Stepping up of voltage is
to reduce the I2R losses in transmitting the power

3. Secondary transmission: The voltage is stepped down at
a receiving station to 33kV or 66kV. The transmission
lines from this station connects substations located near
load centers (cities etc.).
4. Primary distribution: The voltage is stepped down again
to 11kV at a substation. Large industrial consumers can
be supplied at 11kV directly from these substations. Also,
feeders emerge from these substations.

5. Secondary distribution: This system consists of feeders,
distributors and service mains.
Feeders are either overhead lines or underground cables
which carry power close to the load points (end
consumers) up to a couple of kilometers.
Finally, the voltage is stepped down to 415 volts by a pole-
mounted distribution transformer and delivered to the
distributors. End consumers are supplied through a service
mains line from distributors.

POWER
TRANSMISSION
SYSTEM

POWER GENERATION
• Hydel Power generation
• Nuclear Power generation
• Solar Power generation
• Wind Power generation

HYDEL POWER GENERATION

 In this method of generation, water
from higher height is passed into the
water turbine through the pen stock.
 As the water reaches the turbine, it
gains speed after losing the Potential
energy. (Potential energy gets converted
into kinetic energy)
•Kinetic energy of this speedy water
drives the water turbine, which converts
this into mechanical output.
 It drives the coupled generator, which
gives Electrical energy output.

 The amount of water that flows through the
pen stock is controlled by the valves present
in the valve house.
 The valve house has a controlling valve
(=main sluice valve) and a protecting valve
(= an automatic, isolating, “butterfly” type
valve).
 The power control is done by the main
sluice valve
 The “butterfly” valve comes into action if
water flows in opposite direction as a result
of a sudden drop in load on the generator.
 (The pen stock may burst under this
condition)

NUCLEAR POWER
GENERATION
•Nuclear energy is available as a result of fission reaction.
 In a typical system, Uranium 235 is bombarded with neutrons and Heat energy
is released.
 In chain-reaction, these release more neutrons
 Speeds of Neutrons must be reduced to critical speeds for the chain reaction to
take place.
 Moderators (= speed-reducing agents like graphite, heavy water, etc) are used
for this purpose.
 Nuclear fuel rods (of Uranium 235) must be embedded in speed reducing
agents.

NUCLEAR POWER
GENERATION
 Further, control rods (made of cadmium) are required since they are strong
neutron absorbers and help in finely regulating this reaction so that power
control of the generator is precisely obtainable.
 When control rods are pulled out and are away from fuel rods, intensity of
chain reaction increases, which increases the power output of the system.
 When the control rods are pushed in and closer to the fuel rods, the power-
output decreases.
Thus, the electrical load demand on the generator decides (automatically) the
control-rod positions through a very sophisticated control system

NUCLEAR POWER
GENERATION

SOLAR Cells or Photo Voltaic
Cells (P.V. Cells)
 Asolar cell (also known as a photovoltaic
cell or PV cell) is defined as an electrical
device that converts light energy into
electrical energy through the photovoltaic
effect.
 Asolar cell is basically a semi-conductor p-n
junction diode.
 When ionized solar radiation is incident on a
solar cell, the light energy provides sufficient
energy to the PN junction to create free
electrons.
 The movement of these electrons result in
the generation of current.

SOLAR Cells or Photo Voltaic
Cells (P.V. Cells)
•Typical materials used for these cells are: material doped
with boron, cadmium sulphide, gallium arsenide, etc
 An array of large number of such diodes (i.e. Solar cells)
results in higher DC output voltage.
 IfAC electrical energy is required, inverters are used to
convert DC toAC.
 The solar cells are connected in series/parallel
combination to obtain the rated current and voltage

Wind Power Generation

 It contains a horizontal three-bladed
system mounted on a tower.
 The rotation transformation contains
gears to step up the speed and a system
to link the horizontal axis of turbine with
vertical axis of generator.
 When the speed of wind varies, turbine
speed also varies and the output
frequency and voltage of three-phase
alternator vary over a wide range.
 Further, its waveform is also a distorted
one.

Power control circuits required in
wind power generation.
 The variable frequency output
from the wind generator is
converted to constant frequency
voltage output using power
control circuits.
This output is then sent to the
local grid for distribution

Ohm’s Law
Statement: “The voltage across a conductor is directly proportional to
the current flowing through it, provided all physical conditions and
temperature, remain constant”. That is,
V∝ I or V=RI
Where R=constant of proportionality=resistance of the conductor. Its unit
is ohm (Ω)

Key Point
Ohm’s Law can be applied either to the entire circuit or to
the part of a circuit.
If it is applied to entire circuit, the voltage across the entire
circuit and resistance of the entire circuit should be taken
into account.
If the Ohm’s Law is applied to the part of a circuit, then the
resistance of that part and potential across that part should
be used.

Limitations of Ohm’s Law
The limitations of the Ohms law are,
◦It is not applicable to the nonlinear devices
such as diodes, Zener diodes, voltage
regulators etc.
◦It does not hold good for non-metallic
conductors such as silicon carbide.

SERIES CIRCUIT
. The resistance R1, R2 and R3 are said to be in series
𝐑𝐞
𝐪= 𝐑𝟏+ 𝐑𝟐+ 𝐑𝟑
The total or equivalent resistance of series circuit is the arithmetic sum of
resistance connected in series.

SERIES CIRCUIT
Characteristics of Series Circuits
1. The same current flows through each resistance.
2. The equivalent resistance is equal to the sum of the
individual resistances
3. The voltage drop across each resistor will be different.
4. The supply voltage V is the sum of the individual voltage
drops across the resistances.
V = V1+V2+………. +Vn

PARALLEL CIRCUIT

Voltage division in series
circuit of resistors

Current Division in Parallel
Circuit of Resistors

Kirchhoff`s Laws
Kirchhoff’s Current Law or Point Law (KCL)
Statement: “The algebraic sum of
all currents entering and leaving
a node must equal to zero”
In other words, the total current
leaving a junction is equal to the
total current entering that junction.
I1 −I2−I3 + I4−I5 = 0

Kirchhoff`s Laws
Kirchhoff’s Voltage Law or Mesh Law (KVL)
Statement: “The algebraic sum of all voltage drops around any
closed loop is zero”
In other words, Σ IR + Σ e.m.f. = 0 ...round a mesh

Kirchhoff`s Laws
Sign conventions in KVL

INTRODUCTION TO ELECTRICAL ENGINEERING Module 1

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