book

Basic Electrical Engineering

Name: Basic Electrical Engineering
Author: SK Sahdev
ISBN: 9789332558311

by SK Sahdev

April 2015

Beginner

768 pages

23h 29m

English

Pearson Education India

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Cover
Title page
Brief Contents
Contents
Dedication
Preface
Chapter 1 Concepts of Circuit Theory
1.1 Introduction1.2 Electricity1.3 Modern electron theory1.4 Nature of electricity1.5 Charged body1.6 Unit of charge1.7 Free electrons1.8 Electric potential1.9 Potential difference1.10 Electric current1.10.1 Conventional direction of flow of current1.11 Resistance1.11.1 Laws of resistance1.12 Resistivity1.13 Specific resistance1.14 Conductance1.14.1 Conductivity1.15 Electromotive force1.16 EMF and potential difference1.17 Ohm’s law1.17.1 Limitations of ohm’s law1.18 Effect of temperature on resistance1.19 Temperature co-efficient of resistance1.20 Temperature co-efficient of copper at 0°C1.21 Effect of temperature on α1.22 Effect of temperature on resistivity1.23 Electrical energy1.24 Electrical power1.25 Mechanical work1.26 Mechanical power1.27 Heat energy1.28 Joules law of electrical heating1.29 Relation between various quantities1.29.1 Relation between horse power and kW1.29.2 Relation between horse power and torque1.29.3 Relation between kWh and kcal1.30 D.C. Circuits1.31 Series circuits1.32 Parallel circuits1.33 Seriesparallel circuits1.34 Division of current in parallel circuits1.34.1 When two resistors are connected in parallel1.34.2 When three resistors are connected in parallel
Chapter 2 DC Circuit Analysis and Network Theorems
2.1 Introduction2.2 Electric network2.2.1 Active elements2.2.2 Passive elements2.2.3 Network terminology2.3 Voltage and current sources2.3.1 Internal resistance of a source2.3.2 Ideal voltage source2.3.3 Real voltage source2.3.4 Current source2.3.5 Ideal current source2.3.6 Real current source2.3.7 Difference between voltage source and current source2.4 Source transformation (conversion of voltage source to current source and vice versa)2.5 Kichhoff’s laws2.5.1 Kirchhoff’s first law2.5.2 Kirchhoff’s second law2.5.3 Solution of network by kirchhoff’s laws2.6 Wheatstone bridge2.7 Maxwell’s mesh current method (loop analysis)2.8 Nodal analysis2.9 Deltastar and stardelta transformation2.9.1 Delta—star transformation2.9.2 Star—delta transformation2.10 Superposition theorem2.11 Thevenin’s theorem2.12 Norton’s theorem2.13 Conversion of thevenin’s equivalent into norton’s equivalent and vice versa2.14 Maximum power transfer theorem2.15 Reciprocity theorem
Chapter 3 Electrostatics and Capacitors
3.1 Introduction3.2 Coulomb’s laws of electrostatics3.2.1 Unit charge3.3 Absolute and relative permittivity3.4 Electric field3.4.1 Electric lines of force3.5 Electric flux3.6 Electric flux density (D)3.7 Electric intensity or field strength (E)3.8 Relation between σ and E3.9 Area vector3.10 Electric flux through an area3.11 Different ways of charge distribution3.11.1 Linear charge distribution3.11.2 Surface charge distribution3.11.3 Volume charge distribution3.12 Gauss theorem of electrostatics3.12.1 Proof of gauss theorem3.13 Deduction of coulomb’s law from gauss’s law3.14 Electric intensity due to a charged sphere3.14.1 Point P is outside the sphere3.14.2 Point P is inside the sphere3.15 Electric intensity due to a long charged conductor3.16 Electric potential3.16.1 Potential at a point3.16.2 Potential at a point due to number of charges3.17 Electric potential difference3.18 Potential due to charged sphere3.18.1 Potential at the sphere surface3.18.2 Potential inside the sphere3.18.3 Potential outside the sphere3.19 Potential gradient3.20 Breakdown potential or dielectric strength3.21 Capacitor3.21.1 Types of capacitors3.21.2 Capacitor action3.22 Capacitance3.22.1 Dielectric constant or relative permittivity3.22.2 Capacitance of parallel-plate capacitor3.22.3 Factors affecting capacitance3.22.4 Dielectric and its effect on capacitance3.23 Parallel-plate capacitor with composite medium3.23.1 Medium partly air3.23.2 Slab of dielectric is introduced3.24 Multi-plate capacitors3.25 Grouping of capacitors3.25.1 Capacitors in series3.25.2 Capacitors in parallel3.25.3 Capacitors in seriesparallel3.26 Energy stored in a capacitor
Chapter 4 Batteries
4.1 Introduction4.2 Electric cell4.2.1 Forming of a cell4.2.2 EMF developed in a cell4.3 Types of cells4.4 Important terms relating to an electric cell4.5 Grouping of cells4.5.1 Series grouping4.5.2 Parallel grouping4.5.3 Series—parallel grouping4.6 Battery4.6.1 Lead—acid battery4.6.2 Working principle of lead—acid cell4.7 Capacity of a battery4.8 Efficiency of a battery4.9 Charge indications of a lead-acid battery or cell4.10 Charging of lead—acid battery4.11 Care and maintenance of lead—acid batteries4.12 Applications of lead—acid batteries4.13 Nickel—iron alkaline cell4.13.1 Construction4.13.2 Working4.13.3 Discharging4.13.4 Recharging4.13.5 Electrical characteristics4.13.6 Advantages4.13.7 Disadvantages4.14 Comparison between lead—acid and nickel—iron alkaline cell4.15 Nickel—cadmium cell4.15.1 Construction4.15.2 Chemical action during discharging4.15.3 Chemical action during recharging4.15.4 Electrical characteristics4.15.5 Advantages4.15.6 Disadvantages4.16 Small nickel—cadmium cells4.16.1 Silver button cell4.17 Solar cells4.17.1 Applications

Chapter 5 Magnetic Circuits
5.1 Introduction5.2 Magnetic field and its significance5.3 Magnetic circuit and its analysis5.4 Important terms5.5 Comparison between magnetic and electric circuits5.6 Ampere turns calculations5.7 Series magnetic circuits5.8 Parallel magnetic circuits5.9 Leakage flux5.9.1 Fringing5.10 Magnetisation or B—H curve5.11 Magnetic hysteresis5.11.1 Residual magnetism and retentivity5.11.2 Coercive force5.12 Hysteresis loss5.13 Importance of hysteresis loop5.14 Electromagnetic induction5.15 Faraday’s laws of electromagnetic induction5.15.1 First law5.15.2 Second law5.16 Direction of induced emf5.17 Induced emf5.18 Dynamically induced emf5.18.1 Mathematical expression5.19 Statically induced emf5.19.1 Self-induced emf5.19.2 Mutually induced emf5.20 Self-inductance5.20.1 Expressions for self-inductance5.21 Mutual inductance5.21.1 Expression for mutual inductance5.22 Co-efficient of coupling5.22.1 Mathematical expression5.23 Inductances in series and parallel5.23.1 Inductances in series5.23.2 Inductances in parallel5.24 Energy stored in a magnetic field5.25 Ac excitation in magnetic circuits5.26 Eddy current loss5.26.1 Useful applications of eddy currents5.26.2 Mathematical expression for eddy current loss
Chapter 6 AC Fundamentals
6.1 Introduction6.2 Alternating voltage and current6.2.1 Wave form6.3 Difference between ac and dc6.4 Sinusoidal alternating quantity6.5 Generation of alternating voltage and current6.6 Equation of alternating emf and current6.7 Important terms6.8 Important relations6.9 Different forms of alternating voltage equation6.10 Values of alternating voltage and current6.11 Peak value6.12 Average value6.13 Average value of sinusoidal current6.14 Effective or rms value6.15 Rms value of sinusoidal current6.16 Form factor and peak factor6.17 Phasor representation of sinusoidal quantity6.18 Phase and phase difference6.19 Addition and subtraction of alternating quantities6.19.1 Addition of alternating quantities6.19.2 Subtraction of alternating quantities6.20 Phasor diagrams using rms values
Chapter 7 Single-phase AC Circuits
7.1 Introduction7.2 AC circuit containing resistance only7.2.1 Phase angle7.2.2 Power7.2.3 Power curve7.3 AC circuit containing pure inductance only7.3.1 Phase angle7.3.2 Power7.3.3 Power curve7.4 AC circuit containing pure capacitor only7.4.1 Phase angle7.4.2 Power7.4.3 Power curve7.5 AC series circuits7.6 R—L series circuit7.6.1 Phase angle7.6.2 Power7.6.3 Power curve7.7 Impedance triangle7.8 True power and reactive power7.8.1 Active component of current7.8.2 Reactive component of current7.8.3 Power triangle7.9 Power factor and its importance7.9.1 Importance of power factor7.10 Q-factor of a coil7.11 R—C series circuit7.11.1 Phase angle7.11.2 Power7.11.3 Power curve7.11.4 Impedance triangle7.12 R—L—C series circuit7.12.1 Phase angle7.12.2 Power7.12.3 Impedance triangle7.13 Series resonance7.13.1 Resonant frequency7.13.2 Effects of series resonance7.14 Resonance curve7.14.1 Bandwidth7.14.2 Selectivity7.15 Q-factor of series resonant circuit7.16 AC parallel circuits7.17 Methods of solving parallel ac circuits7.18 Phasor (or vector) method7.19 Admittance method7.19.1 Admittance7.19.2 Admittance triangle7.19.3 Conductance7.19.4 Susceptance7.19.5 Solution of parallel ac circuits by admittance method7.20 Method of phasor algebra or symbolic method or J-method7.21 J-notation of phasor on rectangular co-ordinate axes7.21.1 Mathematical representation of phasors7.22 Addition and subtraction of phasor quantities7.22.1 Addition7.22.2 Subtraction7.23 Multiplication and division of phasors7.23.1 Multiplication7.23.2 Division7.24 Conjugate of a complex number7.24.1 Addition7.24.2 Subtraction7.24.3 Multiplication7.25 Powers and roots of phasors7.26 Solution of series and parallel ac circuits by phasor algebra7.27 Parallel resonance7.27.1 Resonant frequency7.27.2 Effect of parallel resonance7.27.3 Resonance curve7.28 Q-factor of a parallel resonant circuit7.29 Comparison of series and parallel resonant circuits
Chapter 8 Three-phase AC Circuits
8.1 Introduction8.2 Polyphase system8.3 Advantages of three-phase system over single-phase system8.4 Generation of three-phase emfs8.4.1 Phasor diagram8.5 Naming the phases8.6 Phase sequence8.7 Double-subscript notation8.8 Interconnection of three phases8.9 Star or wye (Y) connection8.9.1 Relation between phase voltage and line voltage8.9.2 Relation between phase current and line current8.10 Mesh or delta (∆) connection8.10.1 Relation between phase voltage and line voltage8.10.2 Relation between phase current and line current8.11 Connections of three-phase loads8.12 Power in three-phase circuits8.13 Power measurement in three-phase circuits8.14 Three-wattmeter method8.15 Two-wattmeter method8.16 Two-wattmeter method (balanced load)8.16.1 Determination of power factor from wattmeter readings8.16.2 Determination of reactive power from two wattmeter eadings8.17 Effect of power factor on the two wattmeter readings8.17.1 Power factor is unity (cos ɸ = 1) or ɸ = 0°8.17.2 Power factor is 0.5 (cos ɸ = 0.5) or ɸ = 60°8.17.3 Power factor is more than 0.5 But less than one (i.e., 1 > cos ɸ > 0.5) or 60° > ɸ > 0°8.17.4 Power factor is less than 0.5 But more than 0 (i.e., 0.5 > cos ɸ > 0) or 90° > ɸ >60°8.17.5 Power factor is 0 (cos ɸ = 0) or ɸ = 90°
Chapter 9 Measuring Instruments
9.1 Introduction9.2 Concept of measurements9.3 Instruments and their classification9.3.1 Electrical instruments9.4 Methods of providing controlling torque9.4.1 Spring control9.4.2 Gravity control9.5 Methods of providing damping torque9.5.1 Air friction damping9.5.2 Fluid friction damping9.5.3 Eddy current damping9.6 Measuring errors9.6.1 Relative error9.7 Errors common to all types of instruments9.8 Moving iron instruments9.8.1 Attraction-type moving iron instruments9.8.2 Repulsion-type moving iron instruments9.8.3 Advantages and disadvantages of moving iron instruments9.8.4 Errors in moving iron instruments9.8.5 Applications of moving iron instruments9.9 Permanent magnet moving coil instruments9.9.1 Principle9.9.2 Construction9.9.3 Working9.9.4 Deflecting torque9.9.5 Advantages and disadvantages of permanent magnet moving coil instruments9.9.6 Errors in permanent magnet moving coil instruments9.9.7 Range9.10 Difference between ammeter and voltmeter9.11 Extension of range of ammeters and voltmeters9.11.1 Extension of ammeter range9.11.2 Extension of voltmeter range9.12 Dynamometer-type instruments9.12.1 Dynamometer-type wattmeters9.13 Induction-type instruments9.13.1 Induction-type wattmeter9.13.2 Comparison between dynamometer and induction-type wattmeters9.13.3 Induction-type single-phase energy meter9.14 Name plate of energy meter9.15 Connections of single-phase energy meter to supply power to a domestic consumer9.16 Difference between wattmeter and energy meter9.17 Digital multimeter
Chapter 10 Single-phase Transformers
10.1 Introduction10.2 Transformer10.2.1 Necessity10.2.2 Applications10.3 Working principle of a transformer10.4 Construction of a single-phase small rating transformer10.4.1 Core-type transformers10.4.2 Shell-type transformers10.4.3 Berry-type transformers10.5 An ideal transformer10.5.1 Behaviour and phasor diagram10.6 Transformer on dc10.7 EMF equation10.8 Transformer on no-load10.9 Transformer on load10.10 Phasor diagram of a loaded transformer10.11 Transformer with winding resistance10.12 Mutual and leakage fluxes10.13 Equivalent reactance10.14 Actual transformer10.15 Simplified equivalent circuit10.15.1 Equivalent circuit when all the quantities are referred to secondary10.15.2 Equivalent circuit when all the quantities are referred to primary10.16 Expression for no-load secondary voltage10.16.1 Approximate expression10.16.2 Exact expression10.17 Voltage regulation10.18 Approximate expression for voltage regulation10.19 Losses in a transformer10.20 Efficiency of a transformer10.21 Condition for maximum efficiency10.22 All-day efficiency10.23 Transformer tests10.23.1 Open-circuit or no-load test10.23.2 Short circuit test10.24 Autotransformers10.24.1 Construction10.24.2 Working10.25 Autotransformer v/s potential divider10.26 Saving of copper in an autotransformer10.27 Advantages of autotransformer over two-winding transformer10.28 Disadvantages of autotransformers10.29 Applications of autotransformers10.30 Classification of transformers10.31 Power transformer and its auxiliaries
Chapter 11 DC Machines (Generators and Motors)
11.1 Introduction11.2 Electromechanical energy conversion devices (motors and generators)11.3 Electric generator and motor11.3.1 Generator11.3.2 Motor11.4 Main constructional features11.5 Armature resistance11.6 Simple loop generator and function of commutator11.6.1 Commutator action11.7 EMF equation11.8 Types of dc generators11.9 Separately excited dc generators11.10 Self-excited dc generators11.10.1 Cumulative and differential compound-wound generators11.11 Voltage build-up in shunt generators11.12 Critical field resistance of a dc shunt generator11.13 Causes of failure to build-up voltage in a generator11.13.1 Rectification11.14 DC motor11.15 Working principle of dc motors11.15.1 Function of a commutator11.16 Back emf11.16.1 Significance of back emf11.17 Torque equation11.18 Shaft torque11.18.1 Brake horse power11.19 Comparison of generator and motor action11.20 Types of dc motors11.20.1 Separately excited dc motors11.20.2 Self-excited dc motors11.21 Characteristics of dc motors11.22 Characteristics of shunt motors11.23 Characteristics of series motors11.24 Characteristics of compound motors11.25 Applications and selection of dc motors11.26 Necessity of starter for a dc motor11.27 Starters for dc shunt and compound-wound motors11.28 Three-point shunt motor starter11.28.1 Operation11.28.2 No-volt release coil and its function11.28.3 Overload release coil and its function11.29 Losses in a dc machine11.29.1 Copper losses11.29.2 Iron losses11.29.3 Mechanical losses11.30 Constant and variable losses11.31 Stray losses11.32 Power flow diagram11.33 Efficiency of a dc machine11.33.1 Machine working as a generator11.33.2 Machine working as a motor
Chapter 12 Three-Phase Induction Motors
12.1 Introduction12.2 Constructional features of a three-phase induction motor12.3 Production of revolving field12.4 Principle of operation12.4.1 Alternate explanation12.5 Reversal of direction of rotation of three-phase induction motors12.6 Slip12.6.1 Importance of slip12.7 Frequency of rotor currents12.8 Speed of rotor field or mmf12.9 Rotor emf12.10 Rotor resistance12.11 Rotor reactance12.12 Rotor impedance12.13 Rotor current and power factor12.14 Simplified equivalent circuit of rotor12.15 Stator parameters12.16 Induction motor on no-load (rotor circuit open)12.17 Induction motor on load12.17.1 Causes of low-power factor12.18 Losses in an induction motor12.19 Power flow diagram12.20 Relation between rotor copper loss, slip, and rotor input12.21 Rotor efficiency12.22 Torque developed by an induction motor12.23 Condition for maximum torque and equation for maximum torque12.24 Starting torque12.25 Ratio of starting to maximum torque12.26 Ratio of full-load torque to maximum torque12.27 Effect of change in supply voltage on torque12.28 Torque-slip curve12.29 Torque-speed curve and operating region12.30 Effect of rotor resistance on torque-slip curve12.31 Comparison of squirrel-cage and phase-wound induction motors12.32 Necessity of a starter12.33 Starting methods of squirrel-cage induction motors12.33.1 Direct on line (dol) starter12.33.2 Star—delta starter12.33.3 Autotransformer starter12.34 Starting method of slip-ring induction motors12.35 Applications of three-phase induction motors12.36 Comparison between induction motor and synchronous motor12.37 Speed control of induction motors12.37.1 Speed control by changing the slip12.37.2 Speed control by changing the supply frequency12.37.3 Speed control by changing the poles
Chapter 13 Single-Phase Induction Motors
13.1 Introduction13.2 Nature of field produced in single-phase induction motors13.3 Torque produced by single-phase induction motor13.4 Types of motors13.5 Split-phase motors13.5.1 Construction13.5.2 Performance and characteristics13.5.3 Applications13.5.4 Reversal of direction of rotation13.6 Capacitor motors13.6.1 Capacitor start motors13.6.2 Capacitor run motors (fan motors)13.6.3 Capacitor start and capacitor run motors13.7 Shaded pole motor13.7.1 Construction13.7.2 Principle13.7.3 Performance and characteristics13.8 Reluctance start motor13.9 Ac series motor or commutator motor13.9.1 Performance and characteristics13.10 Universal motor13.10.1 Construction13.10.2 Principle13.10.3 Working13.10.4 Applications13.11 Speed control of single-phase induction motors (fan regulator)
Chapter 14 Three-Phase Synchronous Machines
14.1 Introduction14.2 Synchronous machine14.3 Basic principles14.4 Generator and motor action14.5 Production of sinusoidal alternating emf14.6 Relation between frequency speed and number of poles14.7 Constructional features of synchronous machines14.8 Advantages of rotating field system over stationary field system14.9 Three-phase synchronous machines14.10 EMF equation14.11 Working principle of a three-phase synchronous motor14.12 Synchronous motor on load14.13 Effect of change in excitation14.14 V-curves14.15 Application of synchronous motor as a synchronous condenser14.16 Characteristics of synchronous motor14.17 Methods of starting of synchronous motors14.18 Hunting14.19 Applications of synchronous motors
Notes
Acknowledgements
Copyright
Back Cover

Content preview from Basic Electrical Engineering

13 SINGLE-PHASE INDUCTION MOTORS

LEARNING OBJECTIVES

After the completion of this chapter, the students or readers will be able to understand the following:

Why single-phase induction motors are inherently not self-starting?
What arrangements are made to make them self-starting?
What are the different types of single-phase induction motors?
What are the characteristics and applications of various types of single-phase induction motors?
How the speed of a fan motor (single-phase, capacitor run motor) is controlled?

13.1 INTRODUCTION

Although three-phase induction motors are invariably employed in the industry which involves bulk power conversion from electrical to mechanical, single-phase induction motors are mostly used for small power conversion. ...

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Basic Electrical Engineering

by SK Sahdev

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