i SYLLABUS osmania university UNIT - I SYNCHRONOUS MACHINES Constructional Details, Types of Windings, Winding Factors, EMF Equation, Fractional Pitch and Fractional Slot Windings, Suppression of Harmonics and Tooth Ripple, Armature Reaction and Reactance, Synchronous Impedance. UNIT - II SYNCHRONOUS GENERATOR (ALTERNATOR) Voltage Regulation, Phasor Diagram of Alternator With Non-Salient Poles, O.C and S.C Characteristics, Synchronous Impedance, Ampere Turn, ZPF Methods for Finding Regulation, Principle of Two Reaction Theory and Its Application for the Salient Pole Synchronous Machine Analysis, Synchronism and Parallel Operation. UNIT - III SYNCHRONOUS MOTOR Theory of Operation, Vector Diagram, Variation of Current and p.f. with Excitation, Hunting and its Prevention, Current and Power Diagram Predetermination of Performance, Methods of Starting and Synchronizing, Synchronizing Power, Synchronous Condenser. UNIT - IV TRANSIENT STABILITY STUDIES OF SYNCHRONOUS MACHINES Elementary Ideas of Transient Behavior of An Alternator, Three Phase Short Circuit of an Alternator, Elementary Ideas of the Stability of Synchronous Machine Connected to Infinite Bus, Special Machines, Permanent Magnet Motors, Switched Reluctance Motors, Hysteresis Motors.
ii UNIT - V SINGLE-PHASE INDUCTION MOTOR Two Phase Servo Motor Characteristics, Single Phase Motors, Theory and Operation of Single-Phase Motors, Shaded Pole, Split Phase and Capacitor Motor, Compensated and Un-compensated Series and Repulsion Motors, Linear Induction Motors.
iii electrical machinery iii iii FOR b.e. (o.u) IIi year ii semester (ELECTRICAL AND ELECTRONICS ENGINEERING) CONTENTS UNIT - I [SYNCHRONOUS MACHINES]... 1.1-1.94 1.1 INTRODUCTION... 1.2 1.2 CONSTRUCTION OF THREE-PHASE SYNCHRONOUS MACHINE... 1.2 1.2.1 Stator... 1.2 1.2.1.1 Advantages of Rotating Field and Stationary Armature System... 1.3 1.2.2 Rotor... 1.4 1.2.2.1 Salient Pole ole Type Rotor (or) Projecting Pole ole Type... 1.5 1.2.2.2 Non-Salient Pole ole (or) Smooth Cylindrical Pole ole Type Rotor... 1.6 1.2.2.3 Comparison between Salient Pole ole and Non-Salient Pole ole (Cylindrical) Type Rotor... 1.8 1.3 WORKING PRINCIPLE OF THREE-PHASE SYNCHRONOUS MACHINE... 1.9 1.3.1 Mechanical and Electrical Angle... 1.10 1.3.2 Advantages and Disadvantages of Synchronous Machine... 1.11 1.3.3 Frequency of Induced EMF... 1.12 1.3.4 Synchronous Speed (N s )... 1.12 1.3.5 Solved Problems... 1.14
iv 1.4 ARMATURE WINDING... 1.20 1.5 TYPES OF ARMATURE WINDING... 1.21 1.5.1 Single Layer and Double Layer Winding... 1.22 1.5.2 Full-Pitch and Short-Pitch Winding... 1.23 1.5.3 Concentrated and Distributed Winding... 1.24 1.6 WINDING FACT CTORS ORS... 1.25 1.6.1 Distribution Factor (K d )... 1.25 1.6.2 Pitch Factor (K p )... 1.28 1.6.3 Solved Problems... 1.29 1.7 FRACTIONAL PITCH CH AND FRACTIONAL SLOT WINDING... 1.31 1.7.1 Fractional Pitch Winding... 1.31 1.7.2 Fractional Slot Windings... 1.31 1.7.3 Methods of Determining the Layout of Fractional Slot Winding inding... 1.33 1.8 EMF EQUATION... 1.35 1.8.1 Solved Problems... 1.38 1.9 SUPPRESSION OF HARMONICS AND TOOTH TH RIPPLE... 1.58 1.9.1 Tooth Ripple... 1.60 1.9.2 Reduction of Harmonics... 1.60 1.9.3 Effect of Harmonics on Pitch Factor... 1.60 1.9.4 Effect of Harmonic Components on Distribution Factor... 1.61 1.9.5 Total EMF Generated Due to Harmonic Components... 1.61 1.9.6 Solved Problems... 1.62 1.10 ARMATURE REACTION... 1.72 1.10.1 On Unity Power Factor... 1.73 1.10.2 On Lagging Power Factor actor... 1.73 1.10.3 On Leading Power Factor... 1.74
v 1.11 SYNCHRONOUS IMPEDENCE AND PHASOR DIAGRAM OF A SYNCHRONOUS MACHINE... 1.76 1.11.1 Armature Resistance (R a )... 1.80 1.11.2 Armature Leakage Reactance (X L )... 1.80 1.11.3 Synchronous Reactance (X s )... 1.81 1.12 REACT CTANCE OF ARMATURE REACTION (X a )... 1.81 1.12.1 Equivalent Circuit... 1.82 1.13 LOSSES AND EFFICIENCY OF A SYNCHRONOUS MACHINE... 1.82 1.14 RATING OF SYNCHRONOUS MACHINES... 1.85 Short Questions and Answers... 1.87-1.92 Expected University Questions with Answers... 1.93-1.94 UNIT - II [SYNCHRONOUS GENERATOR (ALTERNATOR)]... 2.1-2.82 2.1 INTRODUCTION... 2.2 2.2 WORKING PRINCIPLE OF SYNCHRONOUS GENERATOR OR... 2.2 2.3 PHASOR/VECTOR OR DIAGRAM OF ALTERNA TERNATOR OR WITH NON-SALIENT POLES... 2.4 2.4 VOLTAGE GE REGULATION... 2.6 2.4.1 Determination of Voltage Regulation... 2.7 2.4.2 Measurement of Voltage Regulation egulation... 2.8 2.4.2.1 Determination of Armature Resistance (R a )... 2.8 2.4.2.2 Open-Circuit Characteristic (OCC)... 2.9 2.4.2.3 Short-Circuit Characteristic (S.C.C)... 2.10 2.5 SYNCHRONOUS IMPEDANCE METHOD (OR) EMF METHOD... 2.11 2.5.1 Advantages of Synchronous Impedance Method... 2.14 2.5.2 Disadvantages of Synchronous Impedance Method... 2.15 2.5.3 Solved Problems... 2.15
vi 2.6 AMPERE TURN METHOD (OR) MMF METHOD... 2.26 2.6.1 Solved Problems... 2.31 2.7 ZPF METHOD (OR) POTIER METHOD... 2.35 2.7.1 To Determine E 0, the No-L -Load Induced EMF... 2.37 2.7.2 Solved Problems... 2.38 2.8 TWO REACTION THEORY... 2.47 2.8.1 Principle of Salient-P -Pole Synchronous Machine Two Reaction Model... 2.48 2.8.2 Determination of d From the Phasor Diagram... 2.53 2.8.3 Determination of X and X d q by Slip Test... 2.54 2.8.4 Solved Problems... 2.57 2.9 PARALLEL OPERATION OF ALTERNA TERNATORS... 2.61 2.9.1 Reasons of Parallel Operation... 2.62 2.9.2 Necessary Conditions for Parallel Operation... 2.63 2.9.3 Advantages of Parallel Operation... 2.63 2.10 SYNCHRONIZING ACTION (OR) SYNCHRONISM OF ALTERNA TERNATOR OR... 2.64 2.10.1 Methods of Synchronization... 2.64 2.10.2 Advantages of Synchronism of an Alternators... 2.67 2.11 LOAD SHARING... 2.67 2.11.1 Effect of Change of Excitation... 2.67 2.11.2 Effect of Inequality of EMFs... 2.68 2.11.3 Effect of Change in Mechanical Input... 2.70 2.12 LOSSES IN GENERATOR... 2.71 2.13 EFFICIENCY OF A SYNCHRONOUS GENERATOR OR... 2.71 2.14 RATING OF ALTERNA TERNATOR TOR... 2.72 Short Questions and Answers... 2.73-2.78 Expected University Questions with Answers... 2.79-2.81
vii UNIT - III [SYNCHRONOUS MOTOR]... 3.1-3.88 3.1 INTRODUCTION... 3.2 3.2 PHASOR DIAGRAM OF SYNCHRONOUS MOTOR OR... 3.2 3.2.1 Effect of Loading Synchronous Motor... 3.2 3.2.2 Lagging Power Factor Load... 3.3 3.2.3 Leading Power Factor Load... 3.4 3.2.4 Unity Power Factor Load oad... 3.4 3.3 CONSTRUCTION OF THREE-PHASE SYNCHRONOUS MOTOR OR... 3.6 3.3.1 Stator Construction... 3.6 3.3.2 Rotor Construction... 3.6 3.4 PRINCIPLE OF OPERATION... 3.7 3.5 ADVANT ANTAGES AND DISADVANT ANTAGES OF SYNCHRONOUS MOTOR OR... 3.8 3.6 APPLICATIONS OF SYNCHRONOUS MOTOR OR... 3.9 3.7 METHODS OF STAR ARTING SYNCHRONOUS MOTOR OR... 3.9 3.8 SYNCHRONOUS MOTOR OR ON NO-LO -LOAD AD AND ON-LO ON-LOAD AD... 3.11 3.8.1 Motor on No-Load... 3.11 3.8.2 Motor on On-Load... 3.12 3.9 TORQUES IN SYNCHRONOUS MOTOR OR... 3.13 3.9.1 Torque Angle Characteristics of Synchronous Motor... 3.14 3.10 ANALYSIS OF PHASOR DIAGRAM GRAM... 3.15 3.11 EFFECT OF VARYING EXCIT CITATION TION ON ARMATURE CURRENT AND POWER FACT CTOR OR... 3.16 3.12 V-CURVES AND INVERTED V-CURVES CURVES... 3.18 3.13 BACK EMF... 3.20 3.14 EQUIVALENT CIRCUIT OF SYNCHRONOUS MOTOR OR... 3.21
viii 3.15 POWER FLOW IN SYNCHRONOUS MOTOR OR... 3.23 3.15.1 Power Flow Diagram of Synchronous Motor... 3.25 3.16 ALTERNA TERNATIVE TIVE EXPRESSION FOR POWER DEVELOPED BY A SYNCHRONOUS MOTOR OR... 3.25 3.16.1 Condition for Maximum Power Developed... 3.27 3.16.2 The Value of Maximum Power Developed... 3.27 3.16.3 Condition for Excitation When Motor Develops (P ) m max 3.28 max... 3.28 3.17 BLONDEL DIAGRAM [CONSTANT POWER CIRCLE]... 3.29 3.18 TWO REACTION THEORY FOR SYNCHRONOUS MOTOR OR... 3.33 3.19 HUNTING AND ITS PREVENTION IN SYNCHRONOUS MOTOR OR... 3.36 3.19.1 Causes of Hunting... 3.37 3.19.2 Effects of Hunting... 3.37 3.19.3 Prevention of Hunting... 3.37 3.20 SYNCHRONIZING POWER... 3.38 3.20.1 Alternators Connected to Infinite Busbars... 3.40 3.20.2 Synchronizing Torque... 3.41 3.21 SYNCHRONOUS CONDENSER (OR) SYNCHRONOUS COMPENSATOR OR (OR) SYNCHRONOUS CAPACIT CITOR OR... 3.41 3.21.1 IMPROVEMENT OF POWER FACT CTOR OR... 3.42 3.22 SOLVED PROBLEMS... 3.44 Short Questions and Answers... 3.81-3.85 Expected University Questions with Answers... 3.86-3.88 UNIT - IV [TRANSIENT STABILITY STUDIES OF SYNCHRONOUS MACHINES]... 4.1-4.66 4.1 INTRODUCTION... 4.2 4.2 ELEMENTAR ARY IDEAS OF TRANSIENT BEHAVIOUR OF AN ALTERNA TERNATOR OR... 4.2 4.2.1 Constant Flux Linkage Theorem... 4.2
ix 4.3 SYMMETRICAL SHORT-CIRCUIT TRANSIENT... 4.3 4.3.1 Subtransient Period... 4.5 4.3.2 Transient Period eriod... 4.6 4.3.3 Steady State Period... 4.6 4.4 THREE-PHASE SHORT-CIRCUIT OF AN ALTERNA TERNATOR... 4.7 4.5 ELEMENTAR ARY IDEAS OF THE STABILITY OF SYNCHRONOUS MACHINE CONNECTED TO INFINITE BUS... 4.9 4.5.1 Alternators on Infinite Busbars... 4.10 4.6 POWER OUTPUT EQUATION TION... 4.12 4.6.1 Maximum Power Output... 4.13 4.6.2 Approximate Expression... 4.14 4.6.3 Power Vs Power Angle Characteristic... 4.14 4.7 TWO REACT CTANCE CONCEPT FOR SALIENT POLE MACHINES... 4.15 4.7.1 Power Developed... 4.18 4.7.2 Power Vs Power Angle Characteristic of Salient Pole ole Machine... 4.19 4.8 SPECIAL MACHINES... 4.20 4.9 STEPPER MOTOR OR... 4.20 4.9.1 Types of Stepper Motors... 4.20 4.9.1.1 Variable Reluctance (VR) Stepper Motor... 4.21 4.9.1.2 Permanent Magnet Stepper Motor... 4.29 4.9.1.3 Hybrid Stepper Motor... 4.31 4.9.2 Applications of Stepper Motors... 4.32 4.10 PERMANENT MAGNET DC (PMDC) MOTOR OR... 4.32 4.10.1 Speed Control... 4.34 4.10.2 Advantages of Permanent Magnet DC Motors... 4.34 4.10.3 Disadvantages of Permanent Magnet DC Motors... 4.34 4.10.4 Applications of Permanent Magnet DC Motors... 4.35
x 4.11 PERMANENT MAGNET SYNCHRONOUS MOTOR OR... 4.35 4.11.1 Construction of PMAC Motors... 4.35 4.11.2 Operation of PMAC Motors... 4.35 4.11.3 Sinusoidal PMAC Motors... 4.36 4.11.4 Advantages of PMAC Motor... 4.38 4.11.5 Disadvantages of PMAC Motor... 4.38 4.11.6 Applications of PMAC Motor... 4.38 4.12 SWITCHED RELUCT UCTANCE MOTOR OR (SRM)... 4.38 4.12.1 Construction of SRM.... 4.39 4.12.2 Principle of Operation... 4.41 4.12.3 Voltage and Torque Equation of a SRM... 4.42 4.12.4 Operating Modes... 4.44 4.12.5 Advantages of SRM... 4.47 4.12.6 Disadvantages of SRM... 4.47 4.12.7 Applications of SRM... 4.47 4.13 SINGLE PHASE SYNCHRONOUS MOTOR OR... 4.48 4.13.1 Reluctance Motor... 4.48 4.13.1.1 Construction of Reluctance Motor... 4.49 4.13.1.2 Operation of Reluctance Motor... 4.49 4.13.1.3 Torque orque-speed Characteristics of Reluctance Motor... 4.50 4.13.1.4 Advantages of Reductance Motor... 4.51 4.13.1.5 Disadvantages of Reductance Motor... 4.51 4.13.1.6 Applications of Reductance Motor... 4.51 4.13.1.7 Solved Problem... 4.51
xi 4.13.2 Hysteresis Motor... 4.52 4.13.2.1 Construction of Hysterisis Motor... 4.53 4.13.2.2 Operation of Hysterisis Motor... 4.54 4.13.2.3 Torque orque-speed Characteristic of Hysterisis Motor... 4.57 4.13.2.4 Advatbages of Hysterisis Motor... 4.57 4.13.2.5 Applications of Hysterisis Motor... 4.58 4.14 HYSTERISIS MOTOR OR... 4.58 Short Questions and Answers... 4.59-4.64 Expected University Questions with Answers... 4.65-4.66 UNIT - V [SINGLE PHASE INDUCTION MOTOR]... 5.1-5.78 5.1 INTRODUCTION... 5.2 5.2 CLASSIFICATION OF SINGLE MOTOR OR... 5.2 5.3 SINGLE PHASE INDUCTION MOTOR OR... 5.2 5.4 CONSTRUCTION OF SINGLE-PHASE INDUCTION MOTOR OR... 5.3 5.5 WORKING PRINCIPLE OF SINGLE-PHASE INDUCTION MOTOR OR... 5.4 5.5.1 Double Revolving Field Theory... 5.5 5.5.1.1 Production of Rotating Field... 5.7 5.5.2 Cross Field Theory... 5.8 5.6 EQUIVALENT CIRCUIT OF SINGLE-PHASE INDUCTION MOTOR OR... 5.9 5.6.1 Without Core Loss... 5.9 5.6.2 With Core Loss... 5.12 5.7 CONDUCTING TESTS ON SINGLE-PHASE INDUCTION MOTOR OR... 5.13 5.7.1 No-L -Load Test... 5.13 5.7.2 Blocked Rotor Test... 5.14 5.8 TORQUE-SPEED CHARACTERISTICS... 5.16 5.9 TYPES OF SINGLE-PHASE INDUCTION MOTOR OR... 5.17
xii 5.10 SPLIT PHASE INDUCTION MOTOR OR... 5.17 5.10.1 Torque orque-speed Characteristics of Split Phase Induction Motor... 5.19 5.10.2 Applications of Split Phase Induction Motors... 5.19 5.11 CAPACIT CITOR SPLIT PHASE INDUCTION MOTORS ORS... 5.19 5.11.1 Capacitor Start Motors... 5.19 5.11.2 Capacitor Run Motor (or) Permanent ermanent-slip Capacitor Motors... 5.21 5.11.3 Capacitor Start Capacitor Run Motor (or) Two Value Capacitor Motors... 5.23 5.12 SHADED POLE INDUCTION MOTOR OR... 5.25 5.12.1 Advantages of Shaded Pole ole Inducation Motor... 5.26 5.12.2 Disadvantages of Shaded Pole ole Inducation Motor... 5.26 5.12.3 Torque orque-speed Characteristics of Shaded Pole ole Induction Motor... 5.26 5.12.4 Applications of Shaded Pole ole Induction Motor... 5.27 5.13 COMPENSATED AND UNCOMPENSATED SERIES MOTOR OR... 5.27 5.13.1 Construction... 5.28 5.13.2 Operation... 5.29 5.13.3 Phasor Diagram... 5.30 5.13.4 Applications of AC Series Motors... 5.31 5.14 COMPENSATED AND UNCOMPENSATED REPULSION MOTOR OR... 5.31 5.14.1 Linear Induction Motor (LIM)... 5.33 5.14.2 Repulsion Motor with Single Stator Winding... 5.37 5.15 LINEAR INDUCTION MOTOR OR (LIM)... 5.42 5.15.1 Construction of LIM... 5.42 5.15.2 Principle of LIM... 5.43 5.15.3 Force-Speed Characteristics of LIM... 5.43 5.15.4 Applications of LIM... 5.44
xiii 5.16 COMPARISON OF SINGLE PHASE AND THREE PHASE INDUCTION MOTOR OR... 5.45 5.17 SOLVED PROBLEMS... 5.45 5.18 SERVOMO OMOTORS ORS... 5.66 5.18.1 Types of Servomotors... 5.67 5.18.1.1 DC Servomotors... 5.67 5.18.1.2 AC Servomotors... 5.68 5.19 TWO-PHASE AC SERVO MOTOR OR... 5.68 5.19.1 Applications of Servomotors... 5.70 5.19.2 Advantages of Servomotors... 5.70 Short Questions and Answers... 5.71-5.76 Expected University Questions with Answers... 5.77-5.78 LATEST UNIVERSITY QUESTION PAPER WITH ANSWERS [April/May - 2013] [New] [Main]... QP.1 - QP.10
xiv STUDENT NOTES