Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 5th Sem New 2150904 Elements Of Electrical Design Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? V (New) EXAMINATION ? WINTER 2019
Subject Code: 2150904 Date: 06/12/2019
Subject Name: Elements of Electrical Design
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Define the following terms used in armature winding design:
(1) back pitch (2) Commutator pitch (3) winding pitch
03
(b) Explain the use of dummy coils and equalizer connections in d.c.
armature windings.
04
(c) Design a mush winding for 3-phase, 4-pole and 24 slots stator. Also
show winding diagram for phase R only.
07
Q.2 (a) Give the classification of insulating materials on the basis of maximum
permissible temperature rise.
03
(b) Derive the equation of gap contraction factor for slots. 04
(c) Determine the air gap length of a DC machine from the following data:
Gross core length=0.10m, No. of ducts=1, Width of duct=10mm, slot
pitch=24mm, slot width=12mm, Carter?s co-efficient for slots and
ducts=0.3, gap flux density at pole centre=0.65wb/m
2
, Field mmf per
pole=3800A , mmf required for iron parts of magnetic circuit=600A.
07
OR
(c) Define real and apparent flux densities in the tooth of d.c. machine
armature and give the difference between them. Also derive the
relation between them.
07
Q.3 (a)
Describe how to calculate the magnetizing current in a machine with
distributed winding.
03
(b) Write short note on use of field regulator in case of DC motor and DC
generator.
04
(c) Find the Front pitch, back pitch, winding pitch and commutator pitch
for a simplex wave wound 13 slots, 4-pole d.c armature with 13
commutator segments. Draw the winding diagram in developed form.
Also draw the sequence diagram to indicate the position of brushes.
Assume number of coil sides per slot = 2
07
OR
Q.3 (a) Give the definition of the following terms with respect to load
assessment:
(1) demand factor (2) load factor (3) diversity factor
03
(b) Compare mush winding and double layer winding for three phase AC
machine.
04
(c) Explain the grading of starting resistance for DC Shunt motor starters. 07
Q.4 (a) List any three guidelines for estimation of internal wiring. 03
(b) Discuss briefly the different types of loads with examples. 04
(c) Give design steps for small single phase transformer. 07
OR
Q.4 (a) Discuss the necessity of starter in DC motors and Induction motors. 03
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Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? V (New) EXAMINATION ? WINTER 2019
Subject Code: 2150904 Date: 06/12/2019
Subject Name: Elements of Electrical Design
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Define the following terms used in armature winding design:
(1) back pitch (2) Commutator pitch (3) winding pitch
03
(b) Explain the use of dummy coils and equalizer connections in d.c.
armature windings.
04
(c) Design a mush winding for 3-phase, 4-pole and 24 slots stator. Also
show winding diagram for phase R only.
07
Q.2 (a) Give the classification of insulating materials on the basis of maximum
permissible temperature rise.
03
(b) Derive the equation of gap contraction factor for slots. 04
(c) Determine the air gap length of a DC machine from the following data:
Gross core length=0.10m, No. of ducts=1, Width of duct=10mm, slot
pitch=24mm, slot width=12mm, Carter?s co-efficient for slots and
ducts=0.3, gap flux density at pole centre=0.65wb/m
2
, Field mmf per
pole=3800A , mmf required for iron parts of magnetic circuit=600A.
07
OR
(c) Define real and apparent flux densities in the tooth of d.c. machine
armature and give the difference between them. Also derive the
relation between them.
07
Q.3 (a)
Describe how to calculate the magnetizing current in a machine with
distributed winding.
03
(b) Write short note on use of field regulator in case of DC motor and DC
generator.
04
(c) Find the Front pitch, back pitch, winding pitch and commutator pitch
for a simplex wave wound 13 slots, 4-pole d.c armature with 13
commutator segments. Draw the winding diagram in developed form.
Also draw the sequence diagram to indicate the position of brushes.
Assume number of coil sides per slot = 2
07
OR
Q.3 (a) Give the definition of the following terms with respect to load
assessment:
(1) demand factor (2) load factor (3) diversity factor
03
(b) Compare mush winding and double layer winding for three phase AC
machine.
04
(c) Explain the grading of starting resistance for DC Shunt motor starters. 07
Q.4 (a) List any three guidelines for estimation of internal wiring. 03
(b) Discuss briefly the different types of loads with examples. 04
(c) Give design steps for small single phase transformer. 07
OR
Q.4 (a) Discuss the necessity of starter in DC motors and Induction motors. 03
2
(b) Explain the working of star delta starter with neat sketch for squirrel
cage induction motor.
04
(c) Give the design steps for single phase variable chock coil. 07
Q.5 (a) Explain working of three point starter for DC motor. 03
(b) Discuss types of electrical wiring. 04
(c) Explain the grading of starting resistance for three phase induction
motor starters.
07
OR
Q.5 (a)
List various methods for calculating mmf required for the
tapered teeth and explain any one method in detail.
03
(b) Compare Simplex lap winding & Simplex wave winding. 04
(c) Calculate the steps in a 4 section rotor resistance starter for a 3-phase
induction motor having full load slip 2.5%. Maximum starting current
= full load current and rotor resistance/phase=0.02?.
07
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This post was last modified on 20 February 2020