Electrical Machines-III

16EE220

Syllabus:

UNIT – I:
SYNCHRONOUS GENERATORS
Constructional features of round rotor and salient pole machines. Armature windings –
integral slot and fractional slot, distributed and concentrated, single layer and multi layer,
winding factors. EMF equation, harmonics in generated EMF, suppression of harmonics.
Armature reaction, leakage reactance, synchronous reactance (XS) and impedance(ZS),
Determination of ZS, phasor diagrams. Operating characteristics and ratings of alternators
and problems.

UNIT – II:
REGULATION OF SYNCHRONOUS GENERATOR
Synchronous impedance method (EMF method), Ampere turns method (MMF method), ZPF
method and new ASA method(expand zpf asa). Salient pole alternators, two-reaction theory,
experimental determination of Xd and Xq (slip test), phasor diagrams, regulation of salient
pole alternators. Power flow equations in synchronous generator and problems.

UNIT – III:
PARALLEL OPERATION OF SYNCHRONOUS GENERATORS
Methods of synchronizing alternators. Synchronizing current, power and torque. Effect of
reactance, change of excitation and mechanical power input, unequal voltages. Load sharing
between alternators. Synchronous machines on infinite bus bars. Time period of oscillation
and problems.

UNIT – IV:
SYNCHRONOUS MOTORS
Principle of operation, phasor diagram, variation of current and power factor with excitation,
synchronous condenser, power flow in synchronous motor. Circle diagram – excitation and
power circles. Hunting and its suppression. Methods of starting – auxiliary-motor, damper
winding, synchronous – induction motor and problems.

UNIT – V:
FRACTIONAL KILOWATT MOTORS
Single phase induction motor – constructional features, double revolving field theory, splitphase
motors, shaded pole motor. Construction, principle, characteristics and applications of
AC series motor, universal motor, reluctance motors, stepper motor (types), AC and DC
servo motors.

Materials for EM-III:

Unit-1 : Download

Unit-2 : Download

Unit-3 : Download

Unit-4 : Download

Unit-5 : Download

Question Bank for EM-III:

Unit-1 : Download

Unit-2 : Download

Unit-3 : Download

Unit-4 : Download

Unit-5 : Download

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