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FIRSTMULTICOLOUREDITIONA TEXTBOOK OFELECTRICALTECHNOLOGYVOLUME IBASIC ELECTRICAL ENGINEERINGINS.I. SYSTEM OF UNITS
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A TEXTBOOK OFELECTRICALTECHNOLOGYVOLUME IBASIC ELECTRICAL ENGINEERINGINS.I. SYSTEM OF UNITS(Including rationalized M.K.S.A. System)For the Examinations of B.E. (Common Course to All Branches), B.Tech.,B.Sc. (Engg), Sec. A & B of AMIE(I), A.M.I.E.E. (London), I.E.R.E. (London),Grade I.E.T.E., Diploma and other Competitive ExaminationsB.L. THERAJAA.K. THERAJARevised by :S.G. TARNEKARB.E. (Hons), M.Tech., (El. Machines)Ph.D. (Electrical Power Systems)Former Professor & Head, Electrical Engineering DepartmentVisvesvaraya National Institute of Technology, Nagpur2005S. CHAND & COMPANY LTD.RAM NAGAR, NEW DELHI-110 055S. CHANDAN ISO 9001 : 2000 COMPANY
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APreface to the Twenty-ThirdRevised Multicoloured EditionAuthors feel happy to present to their esteemed readers thisrevised first multicoloured edition of Vol. I of “A Textbook ofElectrical Technology”. To provide a comprehensive treatmentof topics in ‘‘Basic Electrical Engineering’’ both for electrical as wellas non-electrical students pursuing their studies in civil, mechanical,mining,textile,chemical,industrial,environmental,aerospace,electronicand computer engineering, information technology both at the Degreeand Diploma level. Based on the suggestions received from ouresteemed readers, both from India and abroad, the scope of the bookhas been enlarged according to their requirements.Establishment of Technological Universities have taken place inrecent past. This resulted into a pool of expert manpower within alarge area. Unification of syllabi has taken place and the questionpapers set during the last 4-5 years have a wider variety and are ofmore inquisitive nature. Solutions to these with brief logical reasoningshave been added for the benefit of our student community.Many universities include a brief coverage on methods of “ElectricalPower Generation”, in their first and basic paper on this subject.Hence, this revision includes an introductory chapter on this topic.It is earnestly hoped that with these extensive additions andrevisions, this revised edition will prove even more useful to ournumerous readers in developing more confidence while appearing atnational competitive examinations.I would like to thank my Publishers particularly Mr. RavindraKumar Gupta, M.D. and Mr. Bhagirath Kaushik, Regional Manager(Western India) of S. Chand & Company Ltd., for the personal interestthey look in the publishing of this revised and enlarged edition.Our student-friends, teacher-colleagues, Booksellers and Universityauthorities have been showing immense faith and affection in ourbook, which is acknowledged with modesty and regards. We are surethat this revised edition will satisfy their needs to a still greater extentand serve its cause more effectively.S.G. TARNEKAR(v)
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(vi)TPreface to the Twenty-second EditionThe primary objective of Vol. I of A Textbook of ElectricalTechnology is 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, electronicand computer engineering both at the Degree and Diploma level.Based on the suggestions received from our esteemed readers, bothfrom India and abroad, the scope of the book has been enlargedaccording to their requirements. Almost half the solved exampleshave been deleted and replaced by latest examination papers set upto1994 in different engineering colleges and technical institutions inIndia and abroad.Following major additions/changes have been made in the presentedition :1. Three new chapters entitled (a) A.C. Network Analysis (b) A.C.Filter Networks and (c) Fourier Series have been added therebywidening the scope of the book.2. The chapter on Network Theorems has been updated with theaddition of Millman’s Theorem (as applicable to voltage and currentsources or both) and an article on Power Transfer Efficiency relatingto Maximum Power Transfer Theorem.3. The additions to the chapter on Capacitors include detailedarticlesonTransientRelationsduringCapacitorChargingandDischargingCycles and also the Charging and Discharging of a Capacitor withInitial Charge.4. Chapter on Chemical Effects of Current has been thoroughlyrevised with the inclusion of Electronic Battery Chargers, StaticUninterruptable Power Supply (UPS) Systems, High TemperatureBatteries, Secondary Hybrid Cells, Fuel Cells and Aircraft and SubmarineBatteries.5. A detailed description of Thermocouple Ammeter has beenadded to the chapter on Electrical Instruments.6. The chapter on Series A.C. Circuits has been enriched withmany articles such as Determination of Upper and Lower Half-powerFrequencies, Value of Edge Frequencies and Relation betweenResonant Power and Off-resonance Power.It is earnestly hoped that with these extensive additions andrevisions, the present edition will prove even more useful to ournumerous readers than the earlier ones.As ever before, we are thankful to our publishers particularly Sh.Ravindra Kumar Gupta for the personal interest he took in theexpeditious printing of this book and for the highly attractive coverdesign suggested by him. Our sincere thanks go to their hyperactiveand result-oriented overseas manager for his globe-trotting efforts topopularise the book from one corner of the globe to the other. Lastlywe would love to record our sincere thanks to two brilliant ladies; Mrs.Janaki Krishnan from ever-green fairy land of Kerala and Ms. ShwetaBhardwaj from the fast-paced city of Delhi for the secretarial supportthey provided us during the prepration of this book.AUTHORS
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(vii)CONTENTSCONTENTS1. Electric Current and Ohm’s Law ...1—50Electron Drift Velocity—Charge Velocity and Velocity ofField Propagation—The Idea of Electric Potential—Resistance—UnitofResistance—LawofResistance—Unitsof Resistivity—Conductance and Conductivity—Effect ofTemperature on Resistance—Temperature Coefficient ofResistance—Value of a at Different Temperatures—Variation of Resistivity with Temperature—Ohm’s Law—Resistance in Series—Voltage Divider Rule—Resistancein Parallel—Types of Resistors—Nonlinear Resistors—Varistor—Short and Open Circuits—‘Shorts’ in a SeriesCircuit—‘Opens’ in Series Circuit—‘Open’s in a ParallelCircuit—‘Shorts’ in Parallel Circuits—Division of Currentin Parallel Circuits—Equivalent Resistance—DualityBetweenSeriesandParallelCircuits—RelativePotential—Voltage Divider Circuits—Objective Tests.2. DC Network Theorems ...51—174Electric Circuits and Network Theorems—Kirchhoff’sLaws—DeterminationofVoltageSign—AssumedDirectionof Current—Solving Simultaneous Equations—Determinants—SolvingEquationswithTwoUnknowns—Solving Equations With Three Unknowns—Independentand Dependent Sources —Maxwell’s Loop CurrentMethod—Mesh Analysis Using Matrix Form—NodalAnalysis with Voltage Sources—Nodal Analysis withCurrent Sources—Source Conversion—Ideal Constant-Voltage Source—Ideal Constant-Current Source—Superposition Theorem—Thevenin Theorem—How toThevenize a Given Circuit ?—General Instructions forFinding Thevenin Equivalent Circuit—ReciprocityTheorem—Delta/Star Transformation—Star/DeltaTransformation—Compensation Theorem—Norton’sTheorem—How to Nortanize a Given Circuit ?—GeneralInstructions for Finding Norton Equivalent Circuit—Millman’s Theorem—Generalised Form of MillmansTheorem—Maximum Power Transfer Theorem—PowerTransfer Efficiency—Objective Tests.3. Work, Power and Energy ...175—188Effect of Electric Current—Joule’s Law of Electric Heat-ing—Thermal Efficiency—S-I. Units—Calculation ofKilo-watt Power of a Hydroelectric Station—ObjectiveTests.
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4. Electrostatics ...189—212Static Electricity—Absolute and Relative Permittivity of aMedium—Laws of Electrostatics—Electric Field—ElectrostaticInduction—ElectricFluxandFaradayTubes——FieldStrengthorFieldIntensityorElectricIntensity(E)—Electric Flux Density or Electric Displacement D—GaussLaw—The Equations of Poisson and Laplace—ElectricPotentialandEnergy—PotentialandPotentialDifference—Potential at a Point—Potential of a Charged Sphere—Equipotential Surfaces—Potential and Electric IntensityInside a Conducting Sphere—Potential Gradient—BreakdownVoltageandDielectricStrength—SafetyFactorof Dielectric—Boundary Conditions—Objective Tests.5. Capacitance ...213—256Capacitor—Capacitance—Capacitance of an IsolatedSphere—SphericalCapacitor—Parallel-plateCapacitor—Special Cases of Parallel-plate Capacitor—Multiple andVariable Capacitors—Cylindrical Capacitor—PotentialGradientinCylindricalCapacitor—CapacitanceBetweentwo Parallel Wires—Capacitors in Series—Capacitors inParallel—Cylindrical Capacitor with CompoundDielectric—Insulation Resistance of a Cable Capacitor—EnergyStoredinaCapacitor—ForceofAttractionBetweenOppositely-chargedPlates—Current-VoltageRelationshipsinaCapacitor—ChargingofaCapacitor—TimeConstant—Discharging of a Capacitor—Transient Relations duringCapacitor Charging Cycle—Transient Relations duringCapacitor Discharging Cycle—Charging and Dischargingof a Capacitor with Initial Charge—Objective Tests.6. Magnetism and Electromagnetism ...257—296Absolute and Relative Permeabilities of a Medium—LawsofMagneticForce—MagneticFieldStrength(H)—MagneticPotential—Flux per Unit Pole—Flux Density (B)——AbsoluteParmeability(m)andRelativePermeability(mr)—IntensityofMagnetisation(I)—Susceptibility(K)—RelationBetween B, H, I and K—Boundary Conditions—Weberand Ewing’s Molecular Theory—Curie Point. Force on aCurrent-carrying Conductor Lying in a Magnetic Field—Ampere’s Work Law or Ampere’s Circuital Law—Biot-Savart Law—Application of Biot—Savart Law—ForceBetween two Parallel Conductors—Magnitude of MutualForce—Definition of Ampere—Magnetic Circuit—Definitions—Composite Series Magnetic Circuit—Howto Find Ampere-turns ?—Comparison Between Magneticand Electric Circuits—Parallel Magnetic Circuits—Series-(viii)
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ParallelMagneticCircuits—LeakageFluxandHopkinson’sLeakage Coefficient—Magnetisation Curves—Magnetisation curves by Ballistic Galvanometer—Magnetisation Curves by Fluxmete—Objective Tests.7. Electromagnetic Induction ...297—316RelationBetweenMagnetismandElectricity—Productionof Induced E.M.F. and Current—Faraday’s Laws ofElectromagnetic Induction—Direction of Induced E.M.F.andCurrent—Lenz’sLaw—InducedE.M.F.—Dynamically-induced E.M.F.—Statically-induced E.M.F.—Self-Inductance—Coefficient of Self-Inductance (L)—MutualInductance—Coefficient of Mutual Inductance (M)—Coefficient of Coupling—Inductances in Series—Inductances in Parallel—Objective Tests.8. Magnetic Hysteresis ...317—338MagneticHysteresis—AreaofHysteresisLoop—Propertiesand Application of Ferromagnetic Materials—PermanentMagnet Materials—Steinmetz Hysteresis Law—EnergyStored in Magnetic Field—Rate of Change of StoredEnergy—Energy Stored per Unit Volume—Lifting PowerofMagnet—RiseofCurrentinInductiveCircuit—DecayofCurrent in Inductive Circuit—Details of Transient CurrentRise in R-L Circuit—Details of Transient Current Decay inR-LCircuit—AutomobileIgnitionSystem—ObjectiveTests.9. Electrochemical Power Sources ... 339—374Faraday’s Laws of electrolysis—Polarisation or Backe.m.f.—Value of Back e.m.f.—Primary and SecondaryBatteries—Classification of Secondary Batteries baseon their Use—Classification of Lead Storage Batteries—Parts of a Lead-acid Battery—Active Materials of Lead-acid Cells—Chemical Changes—Formation of Platesof Lead-acid Cells—Plante Process—Structure of PlantePlates—Faure Process—Positive Pasted Plates—NegativePasted Plates—Structure of Faure Plates—Comparison: Plante and Faure Plates—Internal Resistance andCapacity of a Cell—Two Efficiencies of the Cell—Electrical Characteristics of the Lead-acid Cell—BatteryRatings—IndicationsofaFully-ChargedCell—Applicationof Lead-acid Batteries—Voltage Regulators—End-cellControl System—Number of End-cells—ChargingSystems—Constant-current System-Constant-voltageSystem—TrickleCharging—Sulphation-CausesandCure—Maintenance of Lead-acid Cells—Mains operated BatteryChargers—Car Battery Charger—Automobile Battery(ix)
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Charger—StaticUninterruptablePowerSystems—AlkalineBatteries—Nickel-iron or Edison Batteries—ChemicalChanges—Electrical Characteristics—Nickel-CadmiumBatteries—Chemical Changes—Comparison : Lead-acidandEdisonCells—Silver-zincBatteries—HighTemperatureBatteries—Secondary Hybrid Cells—Fuel Cells—Hydrogen-Oxygen Fuel Cells—Batteries for Aircraft—Batteries for Submarines—Objective Tests.10. Electrical Instruments and Measurements ...375—452Classification of AC Motors—Induction Motor: GeneralPrincipal—Construction—Squirrel-cage Rotor—Phase-woundRotor—ProductionofRotatingField—Three-phaseSupply—MathematicalProof—WhydoestheRotorRotate?—Slip—Frequency of Rotor Current—Relation betweenTorqueandRotorPowerFactor—StartingTorque—StartingTorque of a Squirrel-cage Motor—Starting Torque of aSlip-ring Motor—Condition for Maximum StartingTorque—Effect of Change in Supply Voltage on StartingTorque—Rotor E.M.F and Reactance under RunningConditions—TorqueunderRunningCondition—Conditionfor Maximum Torque Under Running Conditions—RotorTorqueandBreakdownTorque—RelationbetweenTorqueand Slip—Effect of Change in Supply Voltage on TorqueandSpeed—EffectofChangeinSupplyFrequencyTorqueand Speed—Full-load Torque and Maximum Torque—Starting Torque and Maximum Torque—Torque/SpeedCurve—Shape of Torque/Speed Curve—Current/SpeedCurveofanInductionMotor—Torque/SpeedCharacteristicUnder Load—Plugging of an Induction Motor—InductionMotorOperatingasaGenerator—CompleteTorque/SpeedCurve of a Three-phase Machine—Measurement of Slip—Power Stages in an Induction Motor—Torque Developedby an Induction Motor—Torque, Mechanical Power andRotor Output—Induction Motor Torque Equation—SynchronousWatt—VariationinRotorCurrent—Analogywith a Mechnical Clutch—Analogy with a D.C. Motor—Sector Induction Motor—Linear Induction Motor—Properties of a Linear Induction Motor—MagneticLevitation—Induction Motor as a GeneralizedTransformer—Rotor Output—Equivalent Circuit of theRotor—Equivalent Circuit of an Induction Motor—PowerBalance Equation—Maximum Power Output—Corresponding Slip—Objective Tests.11. A.C. Fundamentals ...453—496Generation of Alternating Voltages and Currents—Equations of the Alternating Voltages and Currents—(x)
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Alternate Method for the Equations of AlternatingVoltages and currents—Simple Waveforms—ComplexWaveforms—Cycle—Time-Period—Frequency—Amplitude—DifferentFormsofE.M.F.Equation—Phase—Phase Difference—Root Mean Square (R.M.S.) Value—Mid-ordinateMethod—AnalyticalMethod—R.M.S.Valueof a Complex Wave—Average Value—Form Factor—Crest or Peak Factor—R.M.S. Value of H.W. RectifiedA.C.—Average Value—Form Factor of H.W. Rectified—Representation of Alternating Quantities—VectorDiagrams Using R.M.S. Values—Vector Diagrams ofSine Waves of Same Frequency—Addition of TwoAlternating Quantities—Addition and Subtraction ofVectors—A.C. Through Resistance, Inductance andCapacitance—A.C. through Pure Ohmic Resistancealone—A.C. through Pure Inductance alone—ComplexVoltage Applied to Pure Inductance—A.C. throughCapacitance alone Objective Tests.12. Complex Numbers ... 497—506Mathematical Representation of Vectors—SymbolicNotation—SignificanceofOperatorj—ConjugateComplexNumbers—TrigonometricalFormofVector—ExponentialForm of Vector—Polar Form of Vector 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—556A.C.throughResistanceandInductance—PowerFactor—Active and Reactive Components of Circuit Current-I—Active, Reactive and Apparent Power—Q-factor ofa Coil—Power in an Iron-cored Chocking Coil—A.C.Through Resistance and Capacitance—Dielectric Lossand Power Factor of a Capacitor—Resistance, InductanceandCapacitanceinSeries—Resonancein R-L-CCircuits—Graphical Representation of Resonance—ResonanceCurve—Half-power Bandwidth of a Resonant Circuit—Bandwidth B at any Off-resonance Frequency—Determination of Upper and Lower Half-PowerFrequencies—Values of Edge Frequencies—Q-FactorofaResonantSeriesCircuit—CircuitCurrentatFrequenciesOther than Resonant Frequencies—Relation BetweenResonant Power P0and Off-resonant Power P—ObjectiveTest.(xi)
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14. Parallel A.C. Circuits ...557—598Solving Parallel Circuits—Vector or Phasor Method—AdmittanceMethod—ApplicationofAdmittanceMethod—Complex or Phasor Algebra—Series-Parallel Circuits—SeriesEquivalentofaParallelCircuit—ParallelEquaivalentof a Series Circuit—Resonance in Parallel Circuits—Graphic Representation of Parallel Resonance—PointstoRemember—BandwidthofaParallelResonantCircuit—Q-factor of a Parallel Circuit—Objective Tests.15. A.C. Network Analysis ...599—626Introduction—Kirchhoffs Laws—Mesh Analysis—NodalAnalysis—Superposition Theorem—Thevenin’sTheorem—Reciprocity Theorem—Norton’s Theorem—Maximum Power Transfer Theorem-Millman’sTheorem.16. A.C. Bridges ...627—640A.C. Bridges—Maxwell’s Inductance Bridge—Maxwell-Wien Bridge—Anderson Bridge—Hay’s Bridge—TheOwenBridge—HeavisideCompbellEqualRatioBridge—CapacitanceBridge—DeSautyBridge—ScheringBridge—Wien Series Bridge—Wien Parallel Bridge—ObjectiveTests.17. A.C. Filter Networks ...641—654Introduction—Applications—Different Types of Filters—Octaves and Decades of frequency—Decible System—Value of 1 dB—Low-Pass RC Filter—Other Types ofLow-Pass Filters—Low-Pass RL Filter—High-Pass R CFilter—High Pass R L Filter—R-C Bandpass Filter—R-CBandstop Filter—The-3 dB Frequencies—Roll-off ofthe Response Curve—Bandstop and Bandpass ResonantFilter Circuits—Series-and Parallel-Resonant BandstopFilters—Parallel-Resonant Bandstop Filter—Series-Resonant Bandpass Filter—Parallel-Resonant BandpassFilter—Objective Test.18. Circle Diagrams ...655—664CircleDiagramofaSeriesCircuit—RigorousMathematicalTreatment—Constant Resistance but VariableReactance—Properties of Constant Reactance ButVariable Resistance Circuit—Simple Transmission LineCircuit.(xii)
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19. Polyphase Circuits ...665—752Generation 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 andCurrents in Y-Connection—Delta (D) or MeshConnection—Balanced Y/D and D/Y Conversions—Star and Delta Connected Lighting Loads—Power FactorImprovement—Power Correction Equipment—ParallelLoads—Power Measurement in 3-phase Circuits—ThreeWattmeter Method—Two Wattmeter Method—Balancedor Unbalanced load—Two Wattmeter Method-BalancedLoad—VariationsinWattmeterReadings—LeadingPowerFactor—Power Factor-Balanced Load—Balanced Load-LPF—Reactive Voltamperes with One Wattmeter—One Wattmeter Method—Copper Required forTransmitting Power Under Fixed Conditions—DoubleSubscript Notation—Unbalanced Loads—UnbalancedD-connectedLoad—Four-wireStar-connectedUnbalancedLoad—UnbalancedY-connectedLoadWithoutNeutral—Millman’s Thereom—Application of Kirchhoffs Laws—Delta/Star and Star/Delta Conversions—UnbalancedStar-connected Non-inductive Load—Phase SequenceIndicators—Objective Tests.20. Harmonics ...753—778Fundamental Wave and Harmonics—Different ComplexWaveforms—General Equation of a Complex Wave—R.M.S. Value of a Complex Wave—Form Factor of aCopmplexWave—PowerSuppliedbyaComplexWave—Harmonics in Single-phase A.C Circuits—SelectiveResonance Due to Harmonics—Effect of Harmonicson Measurement of Inductance and Capacitance—HarmonicsinDifferentThree-phaseSystems—Harmonicsin Single and 3-Phase Transformers—Objective Tests.21. Fourier Series ...779—814Harmonic Analysis—Periodic Functions—TrigonometricFourier Series—Alternate Forms of Trigonometric FourierSeries—Certain Useful Integral Calculus Theorems—Evalulation of Fourier Constants—Different Types ofFunctional Symmetries—Line or Frequency Spectrum—Procedure for Finding the Fourier Series of a GivenFunction—WaveAnalyzer—SpectrumAnalyzer—FourierAnalyzer—Harmonic Synthesis—Objective Tests.(xiii)
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22. Transients ...815—834Introduction—Types of Transients—Important Differ-ential Equations—Transients in R-L Circuits (D.C.),—Short Circuit Current—Time Constant—Transients inR-L Circuits (A.C.)—Transients in R-C Series Circuits(D.C.)—Transients in R-C Series Circuits (A.C)—DoubleEnergy Transients—Objective Tests.23. Symmetrical Components ...835—854Introduction—The Positive-sequence Components—TheNegative-sequenceComponents—TheZero-sequenceComponents—Graphical Composition of SequenceVectors—Evaluation of VA1or V1—Evaluation of VA2orV2—Evaluation VA0or V0—Zero Sequence Componentsof Current and Voltage—Unbalanced Star Load formUnbalanced Three-phase Three-Wire System—Unbalanced Star Load Supplied from Balanced Three-phase Three-wire System—MeasurementofSymmetricalComponents of Circuits—Measurement of Positive andNegative-sequence Voltages—Measurement of Zero-sequence Component of Voltage—Objective Tests.24. Introduction to Electrical Energy Generation ...855—864Preference for Electricity—Comparison of Sources ofPower—Sources for Generation of Electricity—BriefAspects of Electrical Energy Systems—Utility andConsumers—Why is the Three-phase a.c. system MostPopular?—Cost of Generation—Staggering of Loadsduring peak-demand Hours—Classifications of PowerTransmission—Selecting A.C. Transmission Voltagefor a Particular Case—Conventional Sources of ElectricalEnergy—Steam Power Stations (Coal-fired)—NuclearPower Stations—Advantages of Nuclear Generation—Disadvantages—Hydroelectric Generation—Non-Conventional Energy Sources—Photo Voltaic Cells(P.V. Cells or SOLAR Cells)—Fuel Cells—Principle ofOperation—Chemical Process (with Acidic Electrolyte)—Schematic Diagram—Array for Large outputs—HighLights—Wind Power—Background—Basic Scheme—Indian Scenario.Index(xiv)
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