Download A Textbook of Electrical Technology volume 2

A Textbook of Electrical Technology in S.I Units, Vol. 2

A Textbook of Electrical Technology volume 2 – A textbook of electrical technology: volume 2 ac and dc machines elaborately covers the topics, ac and dc machines, which is a part of electrical technology. Electrical technology, as a subject, covers various divisions of electrical engineering like basic electrical engineering, electronics, control systems, instrumentation and communication systems. The book discusses and explains various theories related to ac and dc machines.

The chapters consist of various exercises, examples, and multiple illustrations that aid in understanding the subject better. This book is suitable for students, and has been written in simple language. Various solved examples help in simplifying the subject matter, and the illustrations make it visually more engaging to students. The topics covered in the book range from dc generators and dc motors to alternators and synchronous motors. Special importance has been laid on chapters discussing motors. The objective test section has also been carefully revised

Content – A Textbook of Electrical Technology volume 2

• Elements of Electro-Mechanical Energy Conversion • D.C. Generators • Armature Reaction and Commutation • Generator Characteristics • D.C. Motor • Speed Control of D.C. Motors • Testing of D.C. Machines • Transformer • Transformer: Three Phase • Induction Motor • Computation and Circle Diagrams • Single-Phase Motors • Alternators • Synchronous Motor • Special Machines Index

Detailed Content

CONTENTS

25

  • Elements of Electro- mechanics I Energy Conversion

ms— mb

Introduction Salient aspects of conversions — Energy ha I
ance — Magnetic- Held system: Energy and Co-energy- -Linear
System — A Simple Electromechanical System — In terms of
Field Energy In terms of field Co-energy— Energy in terms of
Elec.tr ka I parameters — Rotary Mol Ion — Description of Simple
System — Energy stored In the colls — Different Categories —
One coJ I each on Stator and oti Rotor Vital Rol e of Air-gap-
Statically induced emf and Dynamically Induced emf.

26 ■ D.C Generators.,.

… 887—936

Generator Principal — -Simple loop Generator — Practical Gen-
erator — Yoke — Pole Cores and Pole Shoes — Pole Coils—
Armature Core Armature Windings Bustles and Bearings —
Pole-p I tch — C onduclor -Coi I and Wi ndlng Elemen t — Coil-span
or Coil -pitch — Pilch of a Winding — Back Pitch — From Pitch —
Resultant Pitch Commutator Pitch .Single layer Winding –
Two-layer Winding — Degree of Re-enlrancy of an Armature
W I ndi ng — -Mult I p lex W i ndl rig — Lap and Wave W i ndl ng — Sim-
ple* -lap Winding Numbering of Coils and Commutator Seg-
ments — Simple* Wave Winding — Dummy or Idle Coils — Uses
oF tap and Wave Windings — Types of Generators — Brush
Contact Drop— Generated E.M.F. or E.M.F. Equation of a
Generator — Iron loss in Armature — Total loss in a D.C.
Generator — Stray Losses — Constant or Standing losses —
Power Stages Condition lor Maximum Efficiency.

27 * Armature Reaction and Commutation

,. 937—966

Arm at use Reaction- Demagnetising and Cross -magnetising
Conductors — Demagnetising AT per Pole — Crossmagnelising
AT per pole Compensating Windings— No. oF Compcnsat
Ing Windings — Commutation — Value of Reactance Voltage —
Mel hods of Improving Comm utal ion — Resistance Commuta-
tion— E.M.F. Commutation — Inlerpotcs or Compotes-
Equalising Connections— Parallel Operation of Shunt Genera-
tors — Paralleling DX Generalor — Load Sharing — Procedure
for Paralleling D.C. Generators — Compound Genera tors in
Parallel — Sertes Generators in Parallel.

(6r)

28 ■ Generator Characteristics

… 967^994

Character is ties of D.C- Generators — Separately-excited Gen-
erator — No-load Carve For Seif-excited Generator — liow to
find Critical Resistance ft? How to draw QC.C ai Different
Speeds ? —Critical Speed — Voltage Build up pf a Shunt Gem
cratm Condition for Build-up of a Shunt Generator Other
Factors Affecting Voltage Building of a D.C. Generator —
External Characteristic — Voltage Regulation — Internal or lo-
13I Characteristic — Series Generator — Compound- wound Gen-
erator -How to calculate Required Scries Turns? -Lises of
D,C. Generators Questions and Answers on DC. Generators,

  1. D,C Motor

i

Motor Principle — Comparison oF Generator and Motor Ac-
tion — Significance oF the Back end — Voltage Equation of a
Motor — Conditions lor Maximum Power — Torque- Arma-
ture Torque of li Motor — Shaft Torcyte — Speed of a D.C.
Motor — Speed RcgulatlonTorque and Speed of a D C. Mo-
tor — Motor Characteristics — Characteristics of Series Mo-
tors — C haracte ris 1 1 c s of S hunt Mol ors — Com pound Motors —
Performance Curves — Comparison of Shunt and Series Mo-
tors— losses and Efficiency — Power Stages,

30 ■ Speed Control of D.C. Motors

995—1030

t J03! — 1090

Factors Controlling Motor Speed — Speed Control of Shunl
Motors — Speed Control of Series Motors — Merits and Demer-
its of Rheostatic Control Me! hod -Series -Parallel Control—
Electric Braking — Electric Braking of Shunt Motor Electric
Braking of Series Motors — Electronic Speed control Method
For D.C. Motors — Uncontrolled Rectifiers — Controlled Recti-
fiers — Thyristor Choppers — Thyristor Inverters — Thyristor
Speed Control of Separately- ex ctled D.C. Motor — Thyristor
Speed Control of D.C. Seres Motor — Full -wave Speed Control
oF a Shunt Motor — Thyristor Control of a Shunt Motor —
Thyristor Speed Control of a Series D.C. Motor — Necessity of
a Starter -Shun! Motor Starler — Three-point Starter -Four

point Starter- Star ting and Speed Control of Series Motors —

Grading of Starting Resistance — Shunt Motors — Series Motor
Starters — Thyristor Controller Starters.

31 » Testing of D C. Machines

Brake Test — Swinburnes Test-— Advantages of Swinburnes
Test — Main Disadvantages- Regenerative or Hnpkinson’s
Test — Alternative Connections Fur Hopklnson’s Te^L — Merits
of Bopki riser’s Test — Retardation or Running Down Test —

(x)

…1091 — II H

Field’s Test For Series Motors — Objective Tests — Questions
and Answers on D C. Motors.

Transfer niei>..

,J 115—12 10

Working Principle ol Tran sfortner— Transformer Construc-
tion Core-type Transformers — Shell type Transformers —
Elementary Theory of an Ideal Transformer — E.M F, Equation
of Transformer — Voltage Transformation Ratio — T rans former
with losses but no Magnetic Leakage— Transformer on No-
Scad- Transformer on Load —Transformer with Winding Re-
sistance bul no Magnetic Leakage — Equivalent Resistance —
Magnetic Leakage — 1 raisfonner with Resistance and Leakage
Reactance— S lm p I i I led Hi agram – Tot a I Approximate Vo I tage
Crop tn Transformer— Exact Voltage Drop — Equivalent Cir-
cuit T ransfor me r T es ts — Open-c ire ui t or No- load T est — Sepa-
ralion of Core Losses — Short-Circuit or Impedence Test —
Why Transformer Rating in KVA? Regulation of a Trans-
former Percentage Resistance, Reactance and Impedance —
Kapp Regulation Diagram — Sumpneror Back-to-back-Test —
Efficiency of a Transformer — Condition (or Maximum Effi-
ciency — Variation oF Efficiency with Power Factor— All-day
Efficiency — Auto transformer — Conversion of 2 -Winding
Transformer Into Au to -t rans Former — Parallel Operation of
Single-phase T rans Formers — Questions and Answers on Trans-
formers

33 * Transformer : Three Phase

r J2II — 1242

Three-phase Transformers Three-phase Transformer C ou-
nce L Ions — 5 1 a r/5 La r of V/V C onnectfon — De I la-De I La or Con –
nect ion — Wye/De 1 i a or Y/ C onn ect Ion — De I taA/Vye or A 1 Con –
n ect i on — Open- Del l a or V- V Connect I on — Power Su pp I Fed by
V-V Bank— Scott Connection or T-T Connection — Three-
phase to Two-Phase Conversion and vice-versa — Parallel Op-
eration of 1-phase T ransformers — instrument T ransformers —
Current Transformers — Potential Transformers.

34

« Induction Motor

…1243 — 1312

Classification of AC Motors — Induction Motor: General Prim
ci pa I — C on M rucl I on- – Sqjjl r re I – cage Rotor— Phase- w£ >u rid
Rotor — Production of Rotating Field — Three-phase Supply —
Mathematical Proof — Why does the Rotor Rotate 7 — Slip —
Frequency of Rotor Current — Relation between Torque and
Rotor Power Factor — Starting Torque —Starling Torque of a
Squirrel -cage Motor — Starting Torque of a Slip-ring Motor —
Condition for Maximum Starling Torque — Effect of Change in
Supply Voltage on Starting Torque — Rotor E.KF and Reac-

ts

lance under Running Conditions — T orque under Running Con-
dition — Condition For Maximum Torque Under Running Con-
ditions — Rotor Torque and Breakdown Torojuc — Relation be-
tween Torque and Slip- Fifed of Change In .Supply Voltage on
Torque and Speed— Effect of Change in Supply Frequency
Torque and Speed — F ull-load T orque and Maximum Torque —
Starting Torque and Max i mum T orque — T orqqe/Specd Curve- –
Shape of Torque/Speed Curve Current/Speed Curve ol an
Induction Motor Torque/Speed Characteristic Linder Load —
Plugging ol an Induction Motor — Induction Motor Operaring
as a Generator — Complete Torque/Specd Curve of a Three*
phase Machine Measurement of Slip — Poster Stages In an
Induction Motor — Torque Developed by an Induction Mo-
tor — Torque. Mechanical Power and Rotor Output — Induction
Motor Torque Equation Synchronous Watt— Variation in
Rolor Current Analogy with a M ethnical Clutch— Analogy
with a D C. Motor — Sector Induction Motor — Linear Induction
Motor — Properties of a Linear Induction Motor — Magnetic
Levitation — Indudlon Motor ns a Generalized Transformer—
Rotor Out pul Equivalent Circuit of the Rotor — Equivalent
Circuit of an Induction Motor — Power Balance Equation —
Maximum Power Output — Corresponding Slip.,

35 ■ Computation And Circle Diagrams

General — Circle Diagram for a Series Circuit— Circle Diagram
of the Approximate Equivalent Circle — Determination of GO
and BO No-load Test- Blocked Rotor Test Construction
or the Circle Diagram— Maximum Quantities — Starting of
Ind ucllon Motors — D Irecl SwJ tch mg or L I ne S i a fling of Induc-
tion MoIofs — Squirrel -cage Motors — Starting of SI Ip- ring
Molors— Slartcr Steps — Crawling — Cogging or Magnetic Lock
lug -Doub I eSqiurrel cage Motor Equivalent circuit — Speed
Control of Induction Motor — Three-Phase A.C. Commutator
Motors — Schrage Motor— Motor Enclosures — Standard type
of Squirrel- cage Motors — Class A Motors- Class B Motors—
Class C Motors Class D Motors Class E Motors — Class F
Motors — Questions and Answer on Induction Motors.

36 ■ Single- Phase Motors

Types of Single-phase Motors — Single-phase Induction Mo-
tor — Double- held Revolving Theory — Making Single-phase
Induction Motor Self-Starling — F.qulvalcni Circuit of Single-
phase Induction Motor — Without Core Loss — Equivalent
Cuicuit — With Core Loss — Types of Capacitors — Start Mo-
tors — Capacitor Start -and -Run Motor — Shaded -pole Single
phase Motor — Repulsion Type Motor?- Repulsion Motor
Repulsion Principle’ Compensated Repulsion Motor — Re-

ixii)

… 1111—1366

puts ion -start Induct Lon -run Motor — Repulsion Induction
Motor — A C Series Motors — Universal Motor — Speed Con-
trol of Universal Motors Unexcited Single -phase Synchro
nous Motors — Reluctance Motor — Hysteresis Motor — Ques-
tions and Answers on Single- phase Motors.

37 * Alternators … 1401 — 1488

Bilik Prlsi cl pie — Stationary Armature- Details of Construe
lion — Rotor — Damper Windings — Speed and Frequency —
Armature Windings — Concentric or Chain Windings — Two-
layer Winding — Wye and Della Connections- Short-pitch
Winding: pitch fatlor/chording factor — Distributfon or Breadth
Factor or Winding Factor or Spread Factor- F.QuaUon of
Induced E.M.F. — EfFect of Harmonics on Pilch and Distribu-
tlon Factors — factors AfTecting Afiernator Size — Alternator
□n Load Synchronous Read ante — Vector D iagrams of I oaded
Alternator — Voltage Regulation- Determination of Voltage
Regulation — Synchronous Impedence Method — Rot her ts
M.M.F. or Ampere- turn Mel hod — General Case— Zero Power
Factor Method or Potter Method — Procedural Steps of Potter
Method- — Operation of Salient Pole Synchronous Machine —
Phaser Diagram k>r a Salient Pole Synchronous Machine —
Calculations from Phaser Diagram — Power Developed by a
Synchonous Generator — parallel Operation of Alternators —
Synchronizing of Alternators ■ -Synchronizing Current- -Syn-
chronizing Power— Alternators Connected to Infinite Bus-
bars — Synchronizing Jerque 1 sy — Effect of Load on Synchro-
nizing Power- Alt cm alive Express I on I nr Synchronizing
Power— Parallel Operation of two Alternators- Effect or Un-
equal Voltages — Distribution of Load — 1 Ime-Period of Osc il-
ia Lion Max I m urn Power Out put— Q ij esl ions and Answers on
Alternators.

38 ■ Synchronous Motor

Synchronou s Motor-General — Pri nciple of Operation — Method
of Starting Motor on Load with Constant Excitation — Power
Flaw within a Synchronous Motor — Equivalent Circuit of a
Synchronous Motor — Power L>evetoped by a Synchronous
Motor -Synchronous Motor with Different Excitations
Effect of Increased Load with Constant Excitation- — Effect of
Changing Excitation of Constant Load — Different Torques of a
Synchronous Motor Power Developed by a Synchronous
Motor — Alternative Expiession for Power Developed— Vari-
ous Conditions of Maxima — Salient Pole Synchronous Mo-
tor – Power Developed by □ Salient Pole Synchronous Motor
— Effects oT Excitation on Armature Current and Power
Factor— Constant-Power Lines — Construction ofV-curves —

… 1489 — -1534

tv/rY>

Hunting or Surging or Phase Swinging Me l: hath of Starling —
Procedure lor Starting a Svnchronoui Motor — Comparison
between Synchronous and Induction Motors — Synchronous
Mol or Applications — Questions arid Answer* on synchronous
Molors.

39* Special Machines

Introduction— Stepper Motor— Types ol Stepper Motors Variable Reluctance Stepper Motors — Multi-stack VR Stepper Motor — Permanent -Magnet Stepping Motor — Hybrid Stepper Motor — S um ma ly o r SI epper Motor — Pcrmanen t -Magtte t DC
Motor— Low- inertia DC Motors— Shell -type Low-inlertia DC
Motor- Printed -circuit (Disc) DC Motor — Permarienl-Mag-
nel Synchronous Motors — Synchros — Type* of Synchros —
Application* of Synchros — Control Dilkrcntial T ransmillcr-
Control Diflcrcnlial Receiver -Switched Reluctance Motor —
Comparison between VR Steppes Motor and SR Motor -The
Resolver — Servomotors — DC Servomotors — AC Servomotors.

Index

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