Download AKTU (Dr. A.P.J. Abdul Kalam Technical University (AKTU), formerly Uttar Pradesh Technical University (UPTU) B-Tech 5th Semester (Fifth Semester) 2015-2016 Electromechanical Energy Conversion Ii Eee 501 Question Paper
(F ollowing Paper ID and Roll No. to be ?lled in your.
Answer Book)
Roll No.
B.Tech.
(SEM. V) THEORY EXAMINATION, 2015-16
ELECTROMECHANICAL ENERGY CONVERSION-II
Time:3 hours] . [Total Marks:100
SECI'ION-A
1. Attempt a_ll parts. All parts carry equal marks. Write
answer of each part in short : (2X10=20)
(a) Why the power factor of the lightly loaded induction
meehihe is quite low?
(b) What do you understand by the term cogging?
(c) Calculate the speed in rpm of a 6 pole induction motor
which has a slip of 6% at full load with a supply
frequency of 50\Hz. What will be the speed of a 4 pole
alternator supplying the motor?
((1) Give application areas of the cylindrical and salient pole .
type synchronous machine.
(1) EEE 501 /2825
(e)
(D
(g)
(h)
(i)
0)
Why in case of three phase synchronous machine, the
armature windings put on stator and ?eld windings put
on rotor whereas in case of DC machine, the armature
windings put on rotor and ?eld windings put on stator
poles?
Draw the V?curves and inverted V-Curves at different
loading conditions of synchronous motor.
De?ne slip. Why the induction motor can?t run at
synchronous speed?
What are the reasons for the Hunting phenomenon in
synchronous machines?
\
State some important application of the stepper motors.
How will you reverse the direction of rotation of the
single phase Induction motor?
SECTION-B
Note: Attempt any ?v_e questions from this section.
( l 0 X 5=50)
Show that in a 3 phase induction motor :
If] _2 ?s?
(2) EEE 501
A 3-phase, 400 V, 50 Hz induction motor take the power .
input of 35 kW at its full load speed of 890 rpm. The
stator losses are 1 kW and friction and windage losses
are 1.5 kW. Calculate :
(i) slip
(ii) Rotor ohmic loss
(iii) Shaft power
(iv) Shaft Torque
. (v) Ef?ciency
From the ?rst principles derive the equivalent circuit
of a three phase induction motor. How the mechanical
load is separated from rotor copper loss in the
equivalent circuit.
Explain the operating principle and constructional
aspects of Deep Bar and Double cage Induction motor. .
Explain how there motors can give higher starting
torque in comparison to the conventional design.
Explain the phenomenon of armature reaction when
alternator is delivering a load current at purely leading
and purely lagging power factor. Also derive the EMF
equation of an alternator.
' (3) EEE 501
O
Derive Torque, Mechanical Power and rotor output
equations of a three phase induction motor connected
from AC mains.
De?ne the term voltage regulation, for the synchrohous
generator. Determine the voltage regulation of a 2000
V, single phase alternator giving current of 100 A at (i)
0.8 pf leading and 0.707 pg lagging. Use the test data
given below2'Full load current of 100A is produced on
short circuit by a ?eld excitation of 2.5A. An EMF of
500 V is generated on open circuit by the same
excitation. The armature resistance being 0.8 Q
Why single phase?induction motor is not self started?
Discuss the different methods of starting a l-phase
Induction motor. /
A 230 V, 50Hz, 4-pol_e single-phase induction motor
has the following equivalent circuit impedances:
R1,? = 2.2 011m. X1", = 3.10hm. R2 ' = 45 ohm.
X2 ' = 2.60hm.XM = 80 ohm
Friction, windage and core loss=40W.
For a slip of0.03 pu, calculate:
i. Input current
ii. Power factor
(4) EEE 501
vmvaq?s. .1...>A~...,.vu~; ?n-l?r-n- 41.. 4:.?? _.
iii: Developed power
iv. Outputpower
v. Ef?ciency
SECTION-C
Note: Attempt any Mg parts of the following:
10.
11.
(2X15=30)
(a) State the necessary conditions for parallel
operation of altemators. Discuss two bright and
one dark lamp method of synchronizing altemators.
(b) A 5000kVA, 10000V, 1500rpm,,50 Hz alternator
runs in parallel with other machine; Its
synchronous reactance is 20% Find for (a) N0-
Load,(b)Full load at p.f. 0.8 Lagging, synchronizing
power per unit mechanical angle of face
displacement and calculate the synchronizing
torque if mechanical displacement is 0.5 degree.
(a) What are the effects ofspace harmonics in 3 phase
induction motors?
(b) The stand still impedances of outer and inner cages
of a double cage induction motors are (2+j1.2)Q
and (0.5+j3.5)Q respectively. Determine the slip
at which the 2 cages develop equal torques.
, (5) mo.
12.'
Discuss the construction detail & working Principle
of the following :
a) Stepper Motors
b) Universal Motors
c) Shaded Pole type Induction Motor.
(6) EEE 501 /2825
This post was last modified on 29 January 2020