B 52046 Pages: 3

Reg No.: Name:

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
FOURTH SEMESTER B.TECH DEGREE EXAMINATION, DECEMBER 2018

Course Code: EE202
Course Name: SYNCHRONOUS AND INDUCTION MACHINES (EE)

Max. Marks: 100 Duration: 3 Hours
PART A
Answer all questions, each carries 5 marks. Mar
(Graph sheets may be supplied) ks
1 Compare salient pole & cylindrical rotor type of alternators. (5)
2 What is armature reaction? Explain the effects of armature reaction in an alternator. (5)

3 Draw the phasor diagram of a salient pole alternator working at a lagging power factor (5)
and derive an expression for the regulation.
4 Sketch and explain the V and inverted V- curves of a synchronous motor. (5)
What is the need for starter in a 3-60 induction motor? Explain the principle of operation (5)
of a star — delta starter.
6 Sketch the equivalent circuit of a double cage induction motor and explain the (5)

parameters.

7 ~ Explain the principle of operation of synchronous induction motor. What are its (5)
advantages over synchronous motors?

8 Why isa 1-0 induction motor not self starting? How is it made self starting? (5)
PART B
Answer any twofull questions, each carries 10 marks.

9 ച Define pitch factor and distribution factor as related to an ac winding. Derive ( 4)
expressions for both.

b) A 3-0, 10 pole alternator has 2 slots/ pole/ phase on its stator with 10 conductors (6)
per slot. The air gap flux is sinusoidally distributed and equals 0.05 Wb. The stator
has a double layer winding with a coil span of 150°E. If the alternator is running
at 600 rpm, calculate the emf generated /phase at no load.

10 a) The following data pertains to ೩ SOOOkVA, 6600 ۷, 3-®, 50 Hz star connected (10)
alternator.
Field current

OC voltage 3100 4900 6600 7500 8300

ZPF voltage (line) | 0 1850 4250 5800 7000
(full load)

Determine the regulation by ZPF method at full load unity power factor. Neglect

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