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ELECTRICAL MACHINES – II  THEORY Theory Portion:
UNIT I ALTERNATOR PRINCIPLE AND CONSTRUCTION Period

Basic Principle of Alternators – Stationary Armature Rotating Field – Advantages of
Rotating Field – Construction details of Alternator – Types of Alternators – Salient
Pole Rotor – Cylindrical Type Rotor – Comparison of Salient pole and Cylindrical pole
Alternator – Single layer and Double layer Windings – Full Pitched and Short Pitched
Windings – Effect of Distribution Factor and Pitch Factor (No derivation) – EMF
Equation – Relation between Frequency, Speed and Number of Poles – Problems –
Cooling of Alternators (Methods only) – Excitation and Exciters.

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UNIT II ALTERNATOR PERFORMANCE AND TESTING Period

Load Characteristics of Alternators – Reason for Change in Terminal Voltage –
Armature Reaction for various Power Factor Loads – Effective Resistance – Leakage
Reactance – Synchronous Reactance – Synchronous Impedance – Voltage
Regulation – Determination of Voltage Regulation of Alternator by Direct Load Test
method – Predetermination of Regulation of Alternator by Indirect Method (EMF,
MMF, and ZPF) (short notes only) – Necessity and conditions for Parallel Operation
of Alternators – Synchronizing of Alternators by Dark Lamp Method, Bright Lamp
Method, Dark – Bright Lamp Method and Synchroscope Method – Synchronizing
Current – Synchronizing Power and Synchronizing Torque – Load Sharing of
Alternators – Infinite Bus Bar.

UNIT III THREE PHASE INDUCTION MOTOR Period
Concept of Rotating Magnetic Field (Short notes only) – Principle of Operation of
Three Phase Induction Motors – Slip and Slip Frequency – Construction of Squirrel
cage and Slip Ring Induction motor – Comparison between Cage and Slip Ring
Induction Motors – Expression for Torque in Synchronous Watts – Slip-Torque
Characteristics – Stable and Unstable Region – Power Stages – Determination of
Maximum Torque – Speed Control of Induction Motors – Starters of Induction
Motors – Direct Online Starter and its merits for Cage Motors – Star Delta Starter –
Auto Transformer Starter – Rotor Resistance Starter – Cogging – Crawling in
Induction Motor – Double cage Induction Motor – Induction Generator.

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UNIT IV SINGLE PHASE MOTORS AND MAINTENANCE OF INDUCTION MOTORS Period
SINGLE PHASE MOTORS:
Types of Single Phase Motors – Single Phase Induction Motors – Methods of
starting – Construction, Working Principle and Slip Torque Characteristics of Split
Phase Motor, Capacitor Motors, Shaded Pole Motor, Repulsion Motor, Universal
Motor and Reluctance Motor – Operation of Three Phase Motor with Single Phase
Supply.
MAINTENANCE OF INDUCTION MOTORS:
BIS Publication dealing with the code of Practice of Induction Motors and starters –
Classification of Cage motors – Continuous rating and intermittent rating – Various
types of enclosures – Selection of Starters for Induction Motor – Common Induction
Motor Troubles and their Remedies – Static Balancing – Degreasing – Vacuum
Impregnation.

UNIT V SYNCHRONOUS MOTOR AND SPECIAL AC MACHINES Period
SYNCHRONOUS MOTOR:
Principle of Operation – Methods of Starting – Effects of Excitation on Armature
Current and Power Factor – V Curve and Inverted V Curve of Synchronous Motor –
The Phenomenon of Hunting and Prevention of Hunting by Damper Winding –
Comparison between Synchronous Motor and Three Phase Induction Motor –
Applications.
SPECIAL AC MACHINES:
Permanent Magnet Synchronous Motor – Switched Reluctance Motor – Variable
Reluctance Motor – AC Servo Motor – Linear Induction Motor.