B D1015 Pages: 2

Reg No.:_ Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
FOURTH SEMESTER B.TECH DEGREE EXAMINATION(R&S), MAY 2019
Course Code: EE202
Course Name: SYNCHRONOUS AND INDUCTION MACHINES (EE)

Max. Marks: 100 Graph sheets shall be provided. Duration: 3 Hours
PARTA
Answer all questions, each carries 5 marks. Marks
1 Derive the emf equation of an alternator. (5)
2 Draw the phasor diagram of a cylindrical rotor type alternator with a) unity (5)

power factor load and (b) leading power factor load

3 Write the necessary conditions for synchronization of alternators. (5)
4 Synchronous motor is not self starting. Why? (5)
5 What is crawling in induction motor? How it can be eliminated? (5)
6 Explain V/f speed control method in 3 phase induction motor. (5)
7 Explain the working principle of synchronous induction motor? (5)
8 Why single-phase induction motor is not self-starting? Also draw its torque - slip (5)
curve?
PART छ
Answer any two full questions, each carries 10 marks.
9 a) Compare salient pole alternator with smooth cylindrical alternator? (4)
b) A 3-phase, 8 pole, 750rpm, star connected alternator has 72 slots on armature. (6)
Each slot has 12 conductors and winding is short pitched by two slots. Find the
induced emf between the lines , given flux per pole 0.06 Wb.
10 Following test results are obtained on a 6600V alternator (10)
Open circuit voltage in volts 3100 4900 6600 7500 8300
Field currents in Amperes 16 25 37.5 50 70
A field current of 20A is found to circulate full load current on armature with
short circuited. Calculate full load regulation at 0.8 pf lag by using mmf method.
Neglect armature resistance.
11 ஐ Explain the causes of harmonics in alternators? How it can be eliminated? (5)

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