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

Course Code: EE409

Course Name: Electrical Machine Design

Max. Marks: 100 Duration: 3 Hours
PARTA
Answer all questions, each carries 5 marks. Marks
1 Establish a relation between apparent flux density and real flux density for the (5)
armature teeth of a DC machine.
2 What are the advantages of square core over rectangular core of a transformer? (5)
3 Explain why a stationary armature and revolving field type of construction is (5)
most convenient for a synchronous generator.
4 What are the important points to be considered while selecting the type of (5)
winding in 60 machine?
5 What are the guiding factors that decide the selection of ampere conductors per (5)
metre of an induction machine?
6 Derive output equation of induction machine. (5)
7 What are the salient points of analysis methods of design of machine? Draw the (5)
flow chart corresponding to analysis method.
8 What are the hybrid techniques available for computer aided design? (5)
PART B

Answer any two full questions, each carries 10 marks.

9 a) What do you understand by continuous, short time and short time intermittent (5)
ratings of an electrical machine?
0) What is carter’s coefficient and how does it help in estimation of mmf of slotted (5)
armature?
10 a) What are the practical aspects of unbalanced magnetic pull that must be (5)
considered while designing electrical machines?
b) Derive the output equation of a three-phase transformer. (5)
1] Calculate the approximate overall dimensions for a 200 kVA, 6600/440 V, 50 (10)
Hz, 3 phase core type transformer. The following data may be assumed: emf per
turn 10 V, maximum flux density = 1.3 Wb/m2, current density = 2.5 A/mm2,
window space factor = 0.3, overall height = overall width, stacking factor = 0.9.
Use a3 stepped core. For a 3 stepped core: Width of largest stamping = 0.9d and
net iron area = 0.602 where ‏ل‎ is the diameter of the circumscribing circle.

PART C

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