Download GTU BE/B.Tech 2017 Winter 6th Sem Old 160804 Electrical Machine Design Question Paper

Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2017 Winter 6th Sem Old 160804 Electrical Machine Design Previous Question Paper

1
Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY
BE SEMESTER-VI OLD) EXAMINATION ? WINTER 2017

Subject Code:160804 Date:13-11-2017
Subject Name: Electrical Machine Design
Time: 02:30 pm to 5:00 pm Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

Q.1 (a) Deduce an expression for the M.M.F required for the air gap of an
armature with slots and ducts.
07
(b) What are the factors that limit the design of an electrical machine? 07

Q.2 (a) Show that for minimum total material cost of a 3-phase transformer the ratio
(Weight of iron/Weight of copper) should be equal to the ratio (specific cost of
Copper (Rs. /kg) / specific cost of iron ((Rs. /kg)).
07
(b) State the advantages of hydrogen cooling in alternators. Explain radial and axial
ventilation with the help of sketches.
07
OR
(b) Deduce an expression for the design of core for Square and cruciform sections
also state the reason why circular coils are always preferred in comparison to
rectangular coils.
07

Q.3 (a) What are the types of windings commonly used in transformer and on what
basis are they selected?
07
(b) Explain :
a. Significance of cruciform core in transformer.
b. Design difference between power & distribution transformer.
07
OR
Q.3 (a) Explain various factors affecting selection of Numbers of armature slots for
D.C. machine.
07
(b) Explain how eddy current loss occurs and derive an expression for eddy current
loss in a magnetic material.
07

Q.4 (a) Define specific magnetic loading (Bav) and specific electric loading (ac) and
obtain an expression for the ?output co-efficient for a d.c. machine.
07
(b) Explain the design procedure in the design of field windings for a D.C. shunt
machine.
07
OR
Q.4 (a) Explain the Real and Apparent flux densities. 07
(b) Explain radial and axial ventilation with the help of sketches. Give the advantages
of hydrogen cooling in alternators.
07

Q.5 (a) Discuss the factors that determine the choice of air-gap in induction motor. 07
(b) List and explain briefly the limitations being imposed in the design of electrical
machines also discuss the modern trends in the design.
07
OR

Q.5 (a) What are the types of windings commonly used in transformer and on what
basis are they selected?
07
(b) Derive the condition for the optimum design of transformer for the minimum cost
and minimum losses.
07

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