Download PTU (I.K. Gujral Punjab Technical University Jalandhar (IKGPTU) ) BE/BTech EEE (Electrical And Electronics Engineering) 2020 March 6th Sem Electrical Machine Previous Question Paper
Roll No. Total No. of Pages : 02
Total No. of Questions : 09
B.Tech. (Electrical & Electronics Engg.) (OE 2012 Onwards) (Sem.?6)
ELECTRICAL MACHINE
Subject Code : BTEEE-OPA
M.Code : 72838
Time : 3 Hrs. Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
1. SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks
each.
2. SECTION-B contains FIVE questions carrying FIVE marks each and students
have to attempt any FOUR questions.
3. SECTION-C contains THREE questions carrying TEN marks each and students
have to attempt any TWO questions.
SECTION-A
1. Write briefly :
a. What would happen if a transformer designed for 50 Hz is connected to a 100 Hz
source of the same voltage?
b. What is the difference between power transformer and distribution transformers?
c. What is the value of slip at standstill position?
d. How to make single-phase induction motor self starting?
e. How can ohmic loss be measured in a transformer?
f. How is the voltage regulation of a transformer affected by a change in its operating
frequency?
g. Why does a 3-phase induction motor always run at a speed less than the synchronous
speed?
h. ?The rotating fields of the stator and rotor are stationary with respect to each other?.
Justify the statement.
i. Why are interpoles designed to provide mmf more than the armature mmf in the
commutating zone?
j. Explain the function of commutator in a dc motor.
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1 | M-72838 (S2)-2205
Roll No. Total No. of Pages : 02
Total No. of Questions : 09
B.Tech. (Electrical & Electronics Engg.) (OE 2012 Onwards) (Sem.?6)
ELECTRICAL MACHINE
Subject Code : BTEEE-OPA
M.Code : 72838
Time : 3 Hrs. Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
1. SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks
each.
2. SECTION-B contains FIVE questions carrying FIVE marks each and students
have to attempt any FOUR questions.
3. SECTION-C contains THREE questions carrying TEN marks each and students
have to attempt any TWO questions.
SECTION-A
1. Write briefly :
a. What would happen if a transformer designed for 50 Hz is connected to a 100 Hz
source of the same voltage?
b. What is the difference between power transformer and distribution transformers?
c. What is the value of slip at standstill position?
d. How to make single-phase induction motor self starting?
e. How can ohmic loss be measured in a transformer?
f. How is the voltage regulation of a transformer affected by a change in its operating
frequency?
g. Why does a 3-phase induction motor always run at a speed less than the synchronous
speed?
h. ?The rotating fields of the stator and rotor are stationary with respect to each other?.
Justify the statement.
i. Why are interpoles designed to provide mmf more than the armature mmf in the
commutating zone?
j. Explain the function of commutator in a dc motor.
2 | M-72838 (S2)-2205
SECTION-B
2. A 6-pole, 3-phase induction motor develops maximum torque at 1000 rpm when operated
from a 60 Hz supply. Rotor resistance per phase is 1.2 ohm. Neglect stator impedance.
Find the speed at which it will develop maximum torque when operated from 50 Hz
source.
3. Derive the equivalent circuit of a single-phase induction motor with the help of double
revolving field theory.
4. Derive torque-current characteristics of dc shunt, series and cumulative compound
motors. Sketch these characteristics in one figure on the assumption of
a. Same torque at no load
b. Rated torque at rated current.
5. Discuss the working of universal motor and draw its equivalent circuit.
6. What is meant by armature reaction of a synchronous machine?
SECTION-C
7. Explain what would happen if the dc motor is directly switched on to the supply without
any starter. Explain the working of three point starter.
8. A 100 kVA, 1000/400 Volts, single-phase transformer, when excited at rated voltage on
h.v. side, draws a no-load current of 3.0 A at 0.5 lagging power factor. If it is excited
from the l.v. side at rated voltage, determine the no load current, power factor and power
input.
9. Explain the function of two stator windings in a single-phase induction motor and
develop the equivalent circuit of single-phase induction motor.
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.
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This post was last modified on 21 March 2020