> 03000EE311092001 Pages: 3

Reg No.: Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
Fifth semester B.Tech degree examinations (S) September 2020

Course Code: EE311
Course Name: ELECTRICAL DRIVES & CONTROL FOR AUTOMATION
Max. Marks: 100 Duration: 3 Hours

PARTA
Answer any three full questions, each carries 10 marks. Marks
1 a) Give the classification of de generators based on their field winding excitation (5)
with diagrams.
b) What are the applications of 60 generator? (3)
c) What is meant by critical speed of a dc shunt generator? (2)
2 a) A 6pole ‏عل‎ shunt generator with 780 wave connected armature conductors and (4)
running at 500rpm supplies a load of 12.5 ohms resistance at a terminal
voltage of 250 V..The armature resistance is 0.25 ohms and field resistance is

250 ohms. Find the following i)Armature current ii)induced EMF iii)Flux per

pole
b) Draw and explain load characteristics of dc shunt generator. (4)
€) What are the effects of armature reaction in a dc generator? (2)
3 ஐ Derive an expression for gross armature torque developed by a 60 motor. (3)
b) Draw and explain torque speed characteristics of 60 series motor. (2)
c) With the help of a neat sketch explain the load test of a dc shunt motor. (5)

4 ಬ A4 pole, 245 V wave connected shunt motor gives 11.19KW power when (5)
running at 1000 rpm and drawing armature and field currents of SOA and 0.8A
respectively. It has 542 armature conductors. Its resistance is 0.15 ohms.
Assuming a drop of 1 volt per brush. Find i) Total torque 11) useful torque 111)
rotational losses iv) efficiency

b) What are the applications of ‏عل‎ shunt, series and compound motors? (3)

c) Explain why we are using starters for starting a 60 motor. (2)

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