Textbook Of Electrical Technology – A Textbook Of Electrical Technology (Multi Colour) is a comprehensive book for electrical engineering students. The book comprises chapters, which cover the entire syllabus of electrical engineering in brief. In addition, the book has multicolor illustrations, which help the students in understanding the concepts better. This book is essential for electrical engineering students and educators alike.

This book has been thoroughly revised and enlarged and will be an asset to both Electrical as well as non-Electrical Students pursuing their studies in different branches of Engineering.

Contents

• Vol. I: Electric Current And Ohm’S Law
• D.C. Network Theorems
• Work, Power And Energy
• Electrostatics Lcapacitance
• Magnetism And Electromagnetism
• Electromagnetic Induction
• Magnetic Hysteresis
• Electronical Power Sources
• Electrical Instruments And Measurements
• A.C. Fundamentals
• Complex Numbers
• Series A.C. Circuits
• Parallel A.C. Circuits
• A.C. Network Analysis
• A.C. Bridges
• A.C. Filter Networks
• Circle Diagrams
• Polyphase Circuits
• Harmonics
• Fourier Series
• Transients
• Symmetrical Components
• Introduction To Electrical Energy Generation

## Detailed Content – Textbook Of Electrical Technology

1. Electric Current and Ohm’s Law …1—50

Electron Drift Velocity — Charge Velocity and Velocity of
Field Propagation— The Idea of Electric Potential-
Resistance — Unit of Resistance — Law of Resistance — Units
of Resistivity— Conductance and Conductivity— Effect of
Temperature on Resistance — Temperature Coefficient of
Resistance— Value of a at Different Temperatures—

Variation of Resistivity with Temperature — Ohm’s Law —

Resistance in Series — Voltage Divider Rule — Resistance
in Parallel — Types of Resistors — Nonlinear Resistors —

Varistor— Short and Open Circuits— ‘Shorts’ in a Series
Circuit — ‘Opens’ in Series Circuit — ‘Open’s in a Parallel
Circuit — ‘Shorts’ in Parallel Circuits — Division of Current
in Parallel Circuits— Equivalent Resistance— Duality
Between Series and Parallel Circuits— Relative Potential-
Voltage Divider Circuits— Objective Tests.

2 . DC Network Theorems

Electric Circuits and Network Theorems — Kirchhoff’s
Laws — Determination ofVoltage Sign — Assumed Direction
of Current— Solving Simultaneous Equations—

Determinants — Solving Equations with Two Unknowns —

Solving Equations With Three Unknowns — Independent
and Dependent Sources — Maxwell’s Loop Current
Method — Mesh Analysis Using Matrix Form — Nodal
Analysis with Voltage Sources — Nodal Analysis with
Current Sources— Source Conversion— Ideal Constant-
Voltage Source— Ideal Constant-Current Source-
Superposition Theorem — Thevenin Theorem — Howto
Thevenize a Given Circuit ? — General Instructions for
Finding Thevenin Equivalent Circuit — Reciprocity
Theorem — Delta/Star T ran sform at ion— Star/Delta
Transformation — Compensation Theorem — Norton’s
Theorem — How to NortanizeaGiven Circuit ? — General
Instructions for Finding Norton Equivalent Circuit —

Millman’s Theorem — Generalised Form of Millman’s
Theorem — Maximum Power Transfer Theorem — Power
Transfer Efficiency — Objective Tests.

3 . Work, Power and Energy

Effect of Electric Current— Joule’s Law of Electric Heat-
ing — Thermal Efficiency — S-l. Units — Calculation of
Kilo-watt Power of a Hydroelectric Station — Objective
Tests.

…51-174

533

CONTENTS

(Vfi)

…189-212

1. Electrostatics

Static Electricity — Absolute and Relative Permittivity of a
Medium — Laws of Electrostatics — Electric Field —
Electrostatic Induction— Electric Flux and Faraday Tubes—
— Field Strength or Field Intensity or Electric Intensity (E) —
Electric Flux Density or Electric Displacement D — Gauss
Law — The Equations of Poisson and Laplace — Electric
Potential and Energy — Potential and Potential Difference —
Potential at a Point— Potential of a Charged Sphere—
Equipotential Surfaces— Potential and Electric Intensity
Inside a Conducting Sphere— Potential Gradient-
Breakdown Voltage and Dielectric Strength— Safety Factor
of Dielectric— Boundary Conditions— Objective Tests.

1. Capacitance

Capacitor— Capacitance— Capacitance of an Isolated
Sphere— Spherical Capacitor— Parallel-plate Capacitor-
Special Cases of Parallel-plate Capacitor— Multiple and
Variable Capacitors— Cylindrical Capacitor— Potential
Gradient in Cylindrical Capacitor— Capacitance Between
two Parallel Wires — Capacitors in Series — Capacitors in
Parallel— Cylindrical Capacitor with Compound
Dielectric— Insulation Resistance of a Cable Capacitor-
Energy Stored in a Capacitor— Force of Attraction Between
Oppositely-charged Plates— Current-Voltage Relationships
in a Capacitor— Charging of a Capacitor— Time Constant-
Discharging of a Capacitor— Transient Relations during
Capacitor Charging Cycle— Transient Relations during
Capacitor Discharging Cycle— Charging and Discharging
of a Capacitor with Initial Charge— Objective Tests.

6 . Magnetism and Electromagnetism

Absolute and Relative Permeabilities ofa Medium — Laws
of Magnetic Force— Magnetic Field Strength (H) — Magnetic

Potential — Flux per Unit Pole — Flux Density (£>)

Absolute Parmeability (m)and Relative Permeability (m ) —
Intensity of Magnetisation (I)— Susceptibility (K) — Relation
Between B, H, I and K— Boundary Conditions — Weber
and Ewing’s Molecular Theory — Curie Point. Force on a
Current-carrying Conductor Lying in a Magnetic Field —
Ampere’s Work Law or Ampere’s Circuital Law— Biot-
Savart Law— Application of Biot— Savart Law— Force
Between two Parallel Conductors — Magnitude of Mutual
Force — Definition of Ampere — Magnetic Circuit —
Definitions — Composite Series Magnetic Circuit — How
to Find Ampere-turns ? — Comparison Between Magnetic
and Electric Circuits— Parallel Magnetic Circuits— Series-

(v/n)

…213-256

…257-296

Parallel MagneticCircuits — Leakage Flux and Hopkinson’s
Leakage Coefficient— Magnetisation Curves—
Magnetisation curves by Ballistic Galvanometer —
Magnetisation Curves by Fluxmete— Objective Tests.

Electromagnetic Induction

Relation Between Magnetism and Electricity — Production
of Induced E.M.F. and Current— Faraday’s Laws of
Electromagnetic Induction — Direction of Induced E.M.F.
and Current — Lenz’s Law— Induced E.M.F. — Dynamically-
induced E.M.F. — Statically-induced E.M.F. — Self-
Inductance— Coefficient of Self-Inductance (L)— Mutual
Inductance— Coefficient of Mutual Inductance (M)—
Coefficient of Coupling — Inductances in Series —
Inductances in Parallel — Objective Tests.

1. Magnetic Hysteresis

Magnetic Hysteresis— Area of Hysteresis Loop— Properties
and Application of Ferromagnetic Materials — Permanent
Magnet Materials — Steinmetz Hysteresis Law — Energy
Stored in Magnetic Field— Rate of Change of Stored
Energy— Energy Stored per Unit Volume — Lifting Power
of Magnet — Rise ofCurrent in Inductive Circuit — Decay of
Current in Inductive Circuit — Details of Transient Current
Rise in R-LCircuit — DetailsofTransientCurrent Decay in
R-L Circuit— Automobile Ignition System— Objective Tests.

9 . Electrochemical Power Sources

…297-316

…317-338

… 339-374

Faraday’s Laws of electrolysis— Polarisation or Back
e.m.f. — Value of Back e.m.f. — Primary and Secondary
Batteries— Classification of Secondary Batteries base
on their Use— Classification of Lead Storage Batteries—
acid Cells — Chemical Changes — Formation of Plates
of Lead-acid Cells— Plante Process— Structure of Plante
Plates— Faure Process— Positive Pasted Plates— Negative
Pasted Plates— Structure of Faure Plates— Comparison
: Plante and Faure Plates— Internal Resistance and
Capacity of a Cell — Two Efficiencies of the Cell —
Electrical Characteristics ofthe Lead-acid Cell— Battery
Ratings— Indications of a Fully-Charged Cell— Application
of Lead-acid Batteries— Voltage Regulators— End-cell
Control System — Number of End-cells — Charging
Systems— Constant-current System-Constant-voltage
System— Trickle Charging— Sulphation-Causes and Cure-
Maintenance of Lead-acid Cells— Mains operated Battery
Chargers— Car Battery Charger— Automobile Battery

OX)

Charger— Static Uninterruptable PowerSystems— Alkaline
Batteries — Nickel-iron or Edison Batteries — Chemical
Batteries— Chemical Changes— Comparison : Lead-acid
and Edison Cells — Silver-zinc Batteries — High Temperature
Batteries— Secondary Hybrid Cells— Fuel Cells—

Hydrogen-Oxygen Fuel Cells — Batteries for Aircraft —

Batteries for Submarines— Objective Tests.

10 . Electrical Instruments and Measurements …375—452

Classification of AC Motors — Induction Motor: General
Principal— Construction— Squirrel-cage Rotor— Phase-
wound Rotor — Production of Rotating Field — Three-phase
Supply— Mathematical Proof— Why does the Rotor Rotate
? — Slip — Frequency of Rotor Current — Relation between
Torque and Rotor Power Factor— Starting Torque— Starting
Torque of a Squirrel-cage Motor— Starting Torque of a
Slip-ring Motor — Condition for Maximum Starting
Torque— Effect of Change in Supply Voltage on Starting
Torque — Rotor E.M.F and Reactance under Running
Conditions — Torque under Running Condition — Condition
for Maximum Torque Under Running Conditions — Rotor
Torque and Breakdown Torque — Relation between Torque
and Slip— Effect of Change in Supply Voltage on Torque
and Speed— Effect of Change in Supply FrequencyTorque
and Speed— Full-load Torque and Maximum Torque-
Starting Torque and Maximum Torque— Torque/Speed
Curve— Shape of Torque/Speed Curve— Current/Speed
Curve of an Induction Motor— Torque/Speed Characteristic
Under Load — Plugging of an Induction Motor— Induction
Motor Operatingasa Generator— Complete Torque/Speed
Curve of a Th ree-phase Mach i ne — Measurement of S I i p —
Power Stages in an Induction Motor— Torque Developed
by an Induction Motor — Torque, Mechanical Power and
Rotor Output— Induction Motor Torque Equation-
Synchronous Watt — Variation in RotorCurrent — Analogy
with a Mechnical Clutch — Analogy with a D.C. Motor —
Sector Induction Motor— Linear Induction Motor —
Properties of a Linear Induction Motor — Magnetic
Levitation — Induction Motor as a Generalized
Transformer — Rotor Output — Equivalent Circuit of the
Rotor— Equivalent Circuit of an Induction Motor — Power
Balance Equation — Maximum Power Output —
Corresponding Slip— Objective Tests.

11 . A.C. Fundamentals …453—496

Generation of Alternating Voltages and Currents—

Equations of the Alternating Voltages and Currents—

M

Alternate Method for the Equations of Alternating
Voltages and currents — Simple Waveforms — Complex
Waveforms — Cycle — Time- Period — Frequency —
Amplitude — Different Forms of E.M.F. Equation — Phase —
Phase Difference — RootMean Square (R.M.S.) Value —
Mid-ordinate Method — Analytical Method — R.M.S. Value
of a Complex Wave — Average Value — Form Factor —
Crest or Peak Factor — R.M.S. Value of H.W. Rectified
A.C. — Average Value— Form Factor of H.W. Rectified
—Representation of Alternating Quantities— Vector
Diagrams Using R.M.S. Values — Vector Diagrams of
Sine Waves of Same Frequency — Addition of Two
Alternating Quantities— Addition and Subtraction of
Vectors— A.C. Through Resistance, Inductance and
Capacitance — A.C. through Pure Ohmic Resistance
alone— A.C. through Pure Inductancealone— Complex
Voltage Applied to Pure Inductance— A.C. through
Capacitance alone Objective Tests.

12

■ Complex Numbers

… 497-506

Mathematical Representation of Vectors — Symbolic
Notation— Significance of Operator/— Conjugate Complex
Numbers — Trigonometrical Form ofVector — Exponential
Form ofVector — Polar Form ofVector Representation —
Addition and Subtraction of Vector Quantities —
Multiplication and Division of Vector Quantities —
Power and Root of Vectors — The 120° Operator —
Objective Tests.

13 . Series A.C. Circuits

…507-556

A.C. through Resistance and Inductance— Power Factor-
Active and Reactive Components of Circuit Current-
I— Active, Reactive and Apparent Power— Q-factor of
a Coil — Power in an Iron-cored Chocking Coil — A.C.
Through Resistance and Capacitance— Dielectric Foss
and Power Factor of a Capacitor— Resistance, Inductance
and Capacitance in Series— Resonance in R-L-C Circuits—
Graphical Representation of Resonance — Resonance
Curve — Half-power Bandwidth of a Resonant Circuit —
Bandwidth B at any Off-resonance Frequency —
Determination of Upper and Fower Half-Power
Frequencies— Values of Edge Frequencies— Q-Factor
ofa Resonant Series Circuit— Circuit Current at Frequencies
Other than Resonant Frequencies — Relation Between
Resonant Power P Q and Off-resonant Power P — Objective
Test.

(m)

14, Parallel A.C. Circuits

…557-598

Solving Parallel Circuits — Vector or Phasor Method —
Complex or Phasor Algebra — Series-Parallel Circuits —
Series Equivalent of a Parallel Circuit — Parallel Equaivalent
of a Series Circuit — Resonance in Parallel Circuits —
Graphic Representation of Parallel Resonance — Points
to Remember — Bandwidth ofa Parallel ResonantCircuit —
Q-factor of a Parallel Circuit— Objective Tests.

1. A.C. Network Analysis

Introduction— Kirchhoff’s Laws — Mesh Analysis — Nodal
Analysis — Superposition Theorem— The venin’s
Theorem — Reciprocity Theorem — Norton’s Theorem —
Maximum Power Transfer Theorem-Millman’s
Theorem.

1. A.C. Bridges

A.C. Bridges — Maxwell’s Inductance Bridge — Maxwell-
Wien Bridge — Anderson Bridge — Hay’s Bridge — The
Owen Bridge — Heaviside Compbell Equal Ratio Bridge —
Capacitance Bridge— DeSauty Bridge— Schering Bridge—
Wien Series Bridge — Wien Parallel Bridge — Objective
Tests.

1. ■ A.C. Filter Networks

Introduction — Applications — Different Types of Filters —
Octaves and Decades of frequency— Decible System-
Value of 1 dB — Low-Pass RC Filter — Other Types of
Low-Pass Filters — Low-Pass RL Filter — High-Pass R C
Filter— High Pass R L Filter— R-C Bandpass Filter— R-C
Bandstop Filter — The-3 dB Frequencies — Roll-off of
the Response Curve— Bandstop and Bandpass Resonant
Filter Circuits— Series-and Parallel-Resonant Bandstop
Filters — Parallel-Resonant Bandstop Filter — Series-
Resonant Bandpass Filter— Parallel-Resonant Bandpass
Filter— Objective Test.

18 ■ Circle Diagrams

Circle Diagram ofaSeriesCircuit — Rigorous Mathematical
Treatment— Constant Resistance but Variable
Reactance— Properties of Constant Reactance But
Variable Resistance Circuit — Simple Transmission Line
Circuit.

(»0

…627-640

…641-654

…655-664

19 ■ Polyphase Circuits

…665-752

Generation of Polyphase Voltages— Phase Sequence-
Phases Sequence At Load— Numbering of Phases—
Interconnection of Three Phases — Star or Wye (Y)
Connection— Values of Phase Currents— Voltages and
Currents in Y-Connection — Delta (D) or Mesh
Connection— Balanced Y/D and D/Y Conversions —
Star and Delta Connected Lighting Loads— Power Factor
Improvement — Power Correction Equipment — Parallel
Loads — Power Measurement in 3-phase Circuits — Three
Wattmeter Method— Two Wattmeter Method — Balanced
or Unbalanced load — Two Wattmeter Method-Ba/anced
LPF — Reactive Voltamperes with One Wattmeter —
One Wattmeter Method — Copper Required for
Transmitting Power Under Fixed Conditions — Double
Mi 1 1 man’s Thereom — Application of Kirchhoff’s Laws —
Delta/Star and Star/Delta Conversions— Unbalanced
Indicators— Objective Tests.

20 . Harmonics

…753-778

Fundamental Wave and Harmonics — Different Complex
Waveforms — General Equation of a Complex Wave —
R.M.S. Value of a Complex Wave — Form Factor of a
Copmplex Wave— Power Supplied by a Com pi ex Wave-
Harmonics in Single-phase A.C Circuits — Selective
Resonance Due to Harmonics — Effect of Harmonics
on Measurement of Inductance and Capacitance —
Harmonics in Different Three-phase Systems — Harmonics
in Single and 3-Phase Transformers — Objective Tests.

21 . Fourier Series

…779-814

Harmonic Analysis — Periodic Functions— Trigonometric
Fourier Series — Alternate Forms of T rigonometric Fourier
Series— Certain Useful Integral Calculus Theorems—
Evaluation of Fourier Constants — Different Types of
Functional Symmetries— Line or Frequency Spectrum —
Procedure for Finding the Fourier Series of a Given
Function — Wave Analyzer — Spectrum Analyzer — Fourier
Analyzer — Harmonic Synthesis — Objective Tests.

(xiii)

22 . Transients

Introduction — Types of Transients — Important Differ-
ential Equations— Transients in R-L Circuits (D.C.),—
Short Circuit Current — Time Constant— Transients in
R-L Circuits (A.C.) — Transients in R-C Series Circuits
(D.C.)— Transients in R-C Series Circuits (A.C)— Double
Energy T ransients— Objective Tests.

Symmetrical Components

Introduction — The Positive-sequence Components —
The Negative-sequence Components— The Zero-sequence
Components— Graphical Composition of Sequence
Vectors— Evaluation of V A1 or V,— Evaluation of V A2 or
V 2 — Evaluation V AO or V 0 — Zero Sequence Components
of Current and Voltage— Unbalanced Star Load form
Unbalanced Three-phase Three-Wire System —
Unbalanced Star Load Supplied from Balanced Three-
phase Three-wire System — MeasurementofSymmetrical
Components of Circuits — Measurement of Positive and
Negative-sequence Voltages— Measurement of Zero-
sequence Component of Voltage— Objective Tests.

24 . Introduction to Electrical Energy Generation

Preference for Electricity — Comparison of Sources of
Power — Sources for Generation of Electricity — Brief
Aspects of Electrical Energy Systems— Utility and
Consumers — Why is the Three-phase a.c. system Most
Popular?— Cost of Generation— Staggering of Loads
during peak-demand Hours — Classifications of Power
Transmission — Selecting A.C. Transmission Voltage
fora Particular Case— Conventional Sources of Electrical
Energy— Steam Power Stations (Coal-fired)— Nuclear
Power Stations — Advantages of Nuclear Generation —
Conventional Energy Sources— Photo Voltaic Cells
(P.V. Cells or SOLAR Cells)— Fuel Cells— Principle of
Operation — Chemical Process (with Acidic Electrolyte) —
Schematic Diagram— Array for Large outputs— High
Lights — Wind Power — Background— Basic Scheme —
Indian Scenario.

Index

…815-834

…835-854

…855-864

(x/’v)

VOLUME – I

BASIC ELECTRICAL
ENGINEERING

Contents

CHAPTER

Learning Objectives

■ Electron Drift Velocity
■ Charge Velocity and

Velocity of Field Propagation

■ The Idea of Electric Potential
Resistance
■ Unit of Resistance
■ Law of Resistance
■ Units of Resistivity
Conductance and
Conductivity

■ Temperature Coefficient of
Resistance

■ Value of a at Different
Temperatures

■ Variation of Resistivity with
Temperature

• Ohm’s Law
■ Resistance in Series
■ Voltage Divider Rule
■ Resistance in Parallel
► Types of Resistors
■ Nonlinear Resistors
■ Varistor

■ Short and Open Circuits
■ ‘Shorts’ in a Series Circuit
■ ‘Opens’ in Series Circuit
■ ‘Open’s in a Parallel Circuit
■ ‘Shorts’ in Parallel Circuits
■ Division of Current in Parallel
Circuits

■ Equivalent Resistance
■ Duality Between Series and
Parallel Circuits
■ Relative Potential
• Voltage Divider Circuits

ELECTRIC
CURRENT
AND OHM S
LAW

Ohm’s law defines the relationship
between voltage, resistance and
current. This law is widely employed
while designing electronic circuits

2 Electrical Technology

1.1. Electron Drift Velocity

Suppose that in a conductor, the number of free electrons
available per m of the conductor material is n and let their
axial drift velocity be v metres/second. In time dt, distance
travelled would be V x dt. If A is area of cross-section of the
conductor, then the volume is vAdt and the number of elec-
trons contained in this volume is vA dt. Obviously, all these
electrons will cross the conductor cross-section in time dt. If
e is the charge of each electron, then total charge which crosses
the section in time dt is dq = nAev dt.

Since current is the rate of flow of charge, it is given as

. _ dq _ nAev dt

dt

dt

i = nAev

The electron moves at the
Fermi speed, and has only
a tiny drift velocity superimposed
by the applied electric field

2

Current density, J = HA = ne V ampere/metre”

Assuming a normal current density J = 1.55 x 10 6 A/m 2 , n = 1 0 2 ’ for a copper conductor
and e = 1.6 x 10 49 coulomb, we get

1.55 x 10 6 = 10 29 x 1.6 x Iff 49 x v .‘.v = 9.1 y. 10 4 m/s = 0.58 cm/min

It is seen that contrary to the common but mistaken view, the electron drift velocity is rather very
slow and is independent of the current flowing and the area of the conductor.

— ^

N.B. Current density i.e., the current per unit area, is a vector quantity. It is denoted by the symbol J .

— >

Therefore, in vector notation, the relationship between current I and J is :

^ ^ >

I — J a [where a is the vector notation for area ‘a’]

For extending the scope of the above relationship, so that it becomes applicable for area of any shape, we
write :

I = J .da

The magnitude of the current density can, therefore, be written as J-cl

Example 1.1. A conductor material has a free-electron density of 10^ 4 electrons per metre 3 .
When a voltage is applied, a constant drift velocity of 1.5 x 10~ metre/second is attained by the
electrons. If the cross-sectional area of the material is 1 cm 2 , calculate the magnitude of the current.
Electronic charge is 1.6 x 10 49 coulomb. (Electrical Engg. Aligarh Muslim University)

Solution. The magnitude of the current is

i = nAev amperes

Here, n = 10~ 4 ; A = 1 cm 2 = 10 4 m 2

e = 1.6 x lO 49 C ; v = 1.5 x 10 4 m/s
i = 10 24 x 10 4 x 1.6 x 10 49 x 1.5 x 10^ = 0.24 A

1.2. Charge Velocity and Velocity of Field Propagation

The speed with which charge drifts in a conductor is called the velocity of charge. As seen from
above, its value is quite low, typically fraction of a metre per second.

However, the speed with which the effect of e.m.f. is experienced at all parts of the conductor
resulting in the flow of current is called the velocity of propagation of electrical field. It is indepen-
dent of current and voltage and has high but constant value of nearly 3 x 10 8 m/s.

Electric Current and Ohm’s Law 3

Example 1.2. Find the velocity of charge leading to 1 A current which flows in a copper
2

## Preface

A Preface to the Twenty-Third Revised Multicoloured Edition Authors feel happy to present to their esteemed readers this revised first multicoloured edition of Vol. I of “A Textbook of Electrical Technology”. To provide a comprehensive treatment of topics in ‘‘Basic Electrical Engineering’’ both for electrical as well as non-electrical students pursuing their studies in civil, mechanical, mining, textile, chemical, industrial, environmental, aerospace, electronic and computer engineering, information technology both at the Degree and Diploma level.Textbook Of Electrical Technology

Based on the suggestions received from our esteemed readers, both from India and abroad, the scope of the book has been enlarged according to their requirements. Establishment of Technological Universities have taken place in recent past. This resulted into a pool of expert manpower within a large area. Unification of syllabi has taken place and the question papers set during the last 4-5 years have a wider variety and are of more inquisitive nature. Solutions to these with brief logical reasonings have been added for the benefit of our student community. Many universities include a brief coverage on methods of “Electrical Power Generation”, in their first and basic paper on this subject. Hence, this revision includes an introductory chapter on this topic. Textbook Of Electrical Technology

It is earnestly hoped that with these extensive additions and revisions, this revised edition will prove even more useful to our numerous readers in developing more confidence while appearing at national competitive examinations. I would like to thank my Publishers particularly Mr. Ravindra Kumar Gupta, M.D. and Mr. Bhagirath Kaushik, Regional Manager (Western India) of S. Chand & Company Ltd., for the personal interest they look in the publishing of this revised and enlarged edition. Our student-friends, teacher-colleagues, Booksellers and University authorities have been showing immense faith and affection in our book, which is acknowledged with modesty and regards. We are sure that this revised edition will satisfy their needs to a still greater extent and serve its cause more effectively Textbook Of Electrical Technology