Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 5th Sem New 2150904 Elements Of Electrical Design Previous Question Paper
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?V (NEW) EXAMINATION ? WINTER 2018
Subject Code:2150904 Date:07/12/2018
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) Write comparison between simplex lap and simplex wave winding applied
to dc armature.
03
(b) Write steps for estimation of domestic wiring.
04
(c) Determine the air gap length of a dc machine from the following
particulars: Gross length of core=0.12 m, no. of ducts=1 and 10 mm wide,
slot pitch=25 mm, slot width = 10 mm, Carter?s coefficient for slots and
ducts =0.32,gap density at pole centre=0.7 wb/m
2
,field mmf per pole
=3900A, mmf required for iron parts of magnetic circuit =800A
07
Q.2 (a) Which are the properties of good insulating materials? 03
(b) Define and clearly explain the terms:
(1) Stacking Factor
(2) Gap contraction factor for slots and ducts
04
(c) Explain grading of starting resistance for DC shunt motor starters. 07
OR
(c) Write steps to design small single phase transformer. 07
Q.3 (a) Write short note on field regulator. 03
(b) Explain the importance of (a) current carrying capacity and (b) voltage drop
while determining the size of conductor
04
(c) Design and develop a mush winding for a 4-pole, 36 slots, 3-phase stator of
ac machine.
07
OR
Q.3 (a) State the rules for electrical wiring as per IS. 03
(b) Compare progressive and retrogressive winding. 04
(c) Calculate the front pitch, back pitch and winding pitch for a simplex lap
wound 16 slot, 4-pole d.c. armature. Make winding table and draw the
winding diagram in developed form. Also draw the sequence diagram to
show the position of brushes. Assume 2 conductor/slot.
07
Q.4 (a) Explain the following:
(1) Load factor (2) Diversity factor (3) Demand factor
03
(b) Write advantages of fractional slot windings. 04
(c) Explain various methods for calculating the mmf required for tapered
teeth.
07
OR
Q.4 (a) Which are the different types of wiring systems used for domestic
installation? Explain any one of them.
03
(b) Generating station has connected load of 50 MW and maximum demand of
30 MW. The units generated 75?10
6
per annum. Calculate (1) Demand
factor (2) Load factor
04
(c) Give the design steps for single phase variable chock coil. 07
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?V (NEW) EXAMINATION ? WINTER 2018
Subject Code:2150904 Date:07/12/2018
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) Write comparison between simplex lap and simplex wave winding applied
to dc armature.
03
(b) Write steps for estimation of domestic wiring.
04
(c) Determine the air gap length of a dc machine from the following
particulars: Gross length of core=0.12 m, no. of ducts=1 and 10 mm wide,
slot pitch=25 mm, slot width = 10 mm, Carter?s coefficient for slots and
ducts =0.32,gap density at pole centre=0.7 wb/m
2
,field mmf per pole
=3900A, mmf required for iron parts of magnetic circuit =800A
07
Q.2 (a) Which are the properties of good insulating materials? 03
(b) Define and clearly explain the terms:
(1) Stacking Factor
(2) Gap contraction factor for slots and ducts
04
(c) Explain grading of starting resistance for DC shunt motor starters. 07
OR
(c) Write steps to design small single phase transformer. 07
Q.3 (a) Write short note on field regulator. 03
(b) Explain the importance of (a) current carrying capacity and (b) voltage drop
while determining the size of conductor
04
(c) Design and develop a mush winding for a 4-pole, 36 slots, 3-phase stator of
ac machine.
07
OR
Q.3 (a) State the rules for electrical wiring as per IS. 03
(b) Compare progressive and retrogressive winding. 04
(c) Calculate the front pitch, back pitch and winding pitch for a simplex lap
wound 16 slot, 4-pole d.c. armature. Make winding table and draw the
winding diagram in developed form. Also draw the sequence diagram to
show the position of brushes. Assume 2 conductor/slot.
07
Q.4 (a) Explain the following:
(1) Load factor (2) Diversity factor (3) Demand factor
03
(b) Write advantages of fractional slot windings. 04
(c) Explain various methods for calculating the mmf required for tapered
teeth.
07
OR
Q.4 (a) Which are the different types of wiring systems used for domestic
installation? Explain any one of them.
03
(b) Generating station has connected load of 50 MW and maximum demand of
30 MW. The units generated 75?10
6
per annum. Calculate (1) Demand
factor (2) Load factor
04
(c) Give the design steps for single phase variable chock coil. 07
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2
Q.5 (a) What is electrical load? How will you classify loads? 03
(b) Explain the working of three point starter with neat sketch for DC Shunt
motor.
04
(c) A gentleman has shop of size 8m?4m. Shop is provided with 3- fan, 4-
tube light and one 5 A 3-pin socket outlet.
(1) Mark suitable location of electrical points in a room and draw
installation plan
(2) Draw wiring diagram
(3) Calculate length of phase wire
07
OR
Q.5 (a) With suitable diagram explain the terms with respect to a.c. armature
winding.
(1) Phase spread (2) Chorded winding (3) Coil span
03
(b) Explain the use of dummy coils and equalizer connections in dc armature
windings.
04
(c) The domestic load in residential building comprises of the following: 6
lamps of 55W each, 4 fans of 60W each, 1 refrigerator of 300W, 1 heater of
1000W, Television of 100W. Calculate (1) The total current taken from the
supply at a voltage of 230 Volts. (2) The energy consumed in a day, if on
average only a quarter of the above load persists all the time. (3) Total cost
of electrical energy for 30 days, at the rate of 5 Rs/Unit.
07
*************
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This post was last modified on 20 February 2020