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H1080 Pages: 2

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
EIGHTH SEMESTER B.TECH DEGREE EXAMINATION, MAY 2019

Course Code: EE402
Course Name: Special Electrical Machines

PARTA
Answer all questions, each carries 5 marks.

Draw and explain the Torque speed curves of an AC servomotor for various
values of control voltage
Define Step angle and detent torque for a Stepper motor.
Explain working principle of two-pole single-phase AC series motor with
diagram.
Explain why rotor position sensor is required for the operation of switched
reluctance motor.
What are the advantages of PMBLDC motor over DC motor?
Differentiate trapezoidal type BLDC motor and sinusoidal type PMBLDC motor
Enumerate linear motors and list any four applications.
Write short note on linear induction motor.

PART B

Answer any two full questions, each carries 10 marks.

Explain the types of series split field DC servomotor.
With relevant diagrams explain field controlled DC Servomotors
Explain any two modes of excitation used in three phase permanent magnet
stepper motor.
Explain the construction of multi stack Variable reluctance stepper motor with
neat sketches.
Compare the performance of AC and DC servo motors and list the applications.
Define the following terms as applied to a Stepper motor (1) Start-stop mode (2)
Slewing mode.

PART C

Answer any two full questions, each carries 10 marks.

Draw the phasor diagram of AC series motor and derive the voltage equation

Derive the torque equation of hysteresis motor

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Duration: 3 Hours

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