Previous year question paper for EM2 (Diploma Electrical Engineering 5th)

1. Synchronous Machines (24hrs)

 1.1 Construction Feature of Stator and Rotor

1.2 Advantages of rotating field system

1.3 Different types of excitation system

1.4 Generation of three phase emf.andemf equation

1.5 Production of rotating magnetic field in a three phase winding

1.6 Concentrated and distributed windings, Concept of distribution factor and

coil span factor and pitch factor

1.7 Effect of armature reaction on terminal voltage when synchronous generator

Independently supplying load at unity lagging and leading power factor

1.8 Concept of synchronous impedance. Voltage regulation and its representation

with phasor diagrams for various power factor loads.

1.9 Voltage Regulation by synchronous impedance method.

1.10 Need and necessary conditions for parallel operation of alternators.

Synchronization of alternators with bus bars Synchroscope method and two lamp

method.

1.11 Operation of synchronous machine as a motor –its starting methods.

1.12 Effect of change in excitation of a synchronous motor, concept of Synchronous

condenser

1.13 Concept and Cause of hunting and its prevention

1.14 Rating and cooling of synchronous machines

1.15 Applications of synchronous machines (as an alternator, as asynchronous

Condenser)

2. Induction Motors (20hrs)

2.1 Salient constructional features of squirrel cage and slip ring 3-phase induction

motors

2.2 Principle of operation of induction motor, slip and its significance

2.3 Effect of slip on various parameters of rotor circuit.

2.4 Power flow diagram and relationship between copper loss and the motor slip

2.5 Factors determining the torque, starting and running torque, maximum torque

Torque-slip curve, stable and unstable zones

2.6 Effect of rotor resistance upon the torque slip relationship

2.7 Double cage rotor motor and its applications

2.8 Starting of 3-phase induction motors, DOL, star-delta, autotransformer

2.9 Testing of 3-phase motor on no load and blocked rotor test and to find Efficiency

2.10 Harmonics and its effects, cogging and crawling in Induction motors.

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3. Fractional Kilo Watt (FKW) Motors

3.1 Single phase induction motors;

3.2 Nature of field produced (double field revolving theory and cross field theory) in

single phase induction motor

3.3 Split phase induction motor

3.3.1 Capacitors start and run motor

3.3.2 Shaded pole motor

3.3.3 Reluctance start motor

3.4 Alternating current series motor and universal motors

3.5 Single phase synchronous motor

3.5.1 Reluctance motor

3.5.2 Hysteresis motor

4. Special Purpose Machines (12 hrs)

Construction and working principle of linear induction motor, steppermotor, Servomotor,

Submersible Motor, Introduction to Energy efficient motors, Brush less DC motors.