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Name:

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
FIFTH SEMESTER B.TECH DEGREE EXAMINATION, APRIL 2018

Course Code: EE311
Course Name: ELECTRICAL DRIVES & CONTROL FOR AUTOMATION (AU, ME)
Max. Marks: 100 Duration: 3 Hours
PART A
Answer any three fuii questions, each carries 10 marks ‏سے‎

1 a) Give the classification of the DC generators depending upon their field excitation (5)
with simple sketches.

b) An 8-pole wave connected DC generator has 1000 armature conductors and flux (2)
per pole is 0.035Wb. At what speed must it be driven to generate 500572

€) Draw the open circuit characteristics of a DC shunt generator and define cntical (3)
resistance.

2 ஐ A DC shunt generator having a terminal voltage of 25011 delivers aload current of (2)
195A. The armature and shunt field resistances are 0.05 ohm and 50 ohms
respectively. Calculate:

i) Armature current ii) Generated emf in armature.

ந) With the help of a neat circuit diagram explain the procedure for obtaining the (6)
internal and external characteristics of 2 DC shunt generator.

€) Write any two methods for compensating the effects of armature reaction in DC (2)
generators.

3 ஐ Explain how the torque is developed in a DC motor? (3)

ந) What 15 meant by back emf in DC motors? A 230 ५ DC shunt motor takes 32 Amp (3)
at full load. Find the back emf on full load if resistances of motor armature and
shunt field windings are 0.2 ohm and 115 ohms respectively.

c) Give the classification of DC motors with applications. (4)

4 a) Draw the power conversion stages of a DC motor. (2)

b) With a neat figure explain the method for conducting load test in a DC shunt (6)
motor.

£) Why starter is necessary in a DC motor? (2)

PART B
Answer any three full questions, each carries 20 marks

5 ३3) A40KVA single phase transformer has 400 turns on the primary and 100 turns on (3)

the secondary. The primary is connected to 2000 V, 50 hz supply. Determine:
1) The Secondary voltage on open circuit
11) Maximum value of flux.

b) Draw the phasor diagram of a single-phase transformer with inductive load and (2)
mark each phasor clearly.

€) What is an auto transformer? With suitable derivations, prove that there is saving (5)
of copper in auto transformer compared to ordinary transformer.

6 a) Obtain the approximate equivalent circuit With respect to low voltage side of a (6)
given 200/2000 V single phase 30 KVA transformer having the following test
results.

O.C test:- 200V, 6.2A, 360W on 1.४, side
S.C test:- 75 ४, 188, 600۷۷ on H.V side
ए) Define the all-day efficiency of 8 distribution transformer. What is its significance? (2)

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