Printed Pages : 3
EEEO12
(Following Paper rD and Roll No. to be filled in your Answer Book)
Roll No.
B.Tech.
(SEMESTER VD THEORY EXAMINATION, 2012-13
SPECIAL ELE CTRICAL MACHII\'ES
Time:3 HoursJ tTotalMarks:121
SECTION _ A
1. Attempt all question parts : l0 x 2 :20
(a) What are the different ways of controlling slip ?
(b) Draw the torque-slip characteristics for double cage.
(c) Name the different types of fractional kilowatt Motor.
(d) Sketch the circuit diagram of capacitor start, capacitor run Induction motor & draw
speed-torque characteristic.
(e) compare variable reluctance & permanent magnet stepper motor.
(0 What are the different mode of operation of SRM ? (Switch Reluctance Motor)
(g) List out the applications of Brushless DC motor. !
(h) Differentiate hysteresis & reluctance motor.
:
(i) What are the characteristics of universal motor ?
0) What is Linear Induction motor ?
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SECTION _ B
2. Attempt any three question parts : 3x 10:30
(a) (i) Explain the magnetizing & demagnetizing characteristics using B-H loop.
(iD Draw and explain permanent magnet DC motor.
O) With neat sketch, explain the construction of Double cage rotor.
(c) Explain the construction, working principle & torque-speed characteristics of shaded
pole Induction motor
(d) With neat sketch, explain briefly about the construction and working principle of
repulsion motor.
(e) Explain the construction and principle of operation of Hybrid stepper motor.
SECTION - C
Attempt all questions : 5x10=50
3. Attemptanytwoparts: 2x5=10
(a) Explain the principle of slip control by slip frequency EMF injection in rotor circuit
with neat sketch.
(b) Write a note on the construction of deep bar tnduction moto{.
(c) A 3 phase 50 Hz, 12 pole,200 kW slip ring Induction motor drives a pump whose
torque is proportional to the square of speed. At full load the motor slip is 0.045.
The rotor resistance measured between any two. slip ring is 0.61 mO . What
resistance should be added in the rotor circuit to reduce the speed of pump to 450
rpm ?
4. Attempt any one part : 1x10=10
(a) Explain the construction, working principle & torque-speed characteristics of two-
phase AC servomotor.
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O) The main & auxiliary winding impedances of a 50 Hz, capacitor start single phase
induction motor are
Mainwinding : 3+j2.7
Auxiliarywinding 7+ j3
Determine the value of the capacitor to be connected in series to achieve a phase
difference of cl:90o between the currents of two windings at start.
5. Attempt any one part : I x 10: 10
(a) With neat sketch, explain briefly about the construction and working principle of
Universal motor.
(b) A universal motor with 960 conductors. At a certain load, the motor
has its 2 poles
speed is 5000 rym & the armature current is 4.6 amps. The armature terminal
voltage and power are 100 volt & 300 watts respectively. Compute the following,
assuming armature resistance of 3.5 ohm :
(i) Effective armature reactance
(ii) Maximum value of flux/pole
6. Attempt any one part : x 10 = l0
(a) With neat sketch, explain the construction, operating principle & characteristics of
Hysteresis motor. ''
(b) With neat sketch, explain the construction, operating principle & characteristics of
Brushless DC motor.
7. Attempt any two parts : 2x5=10
(a) With neat sketch, explain any one of drive circuit of'stepper riotor.
.
(b) What are static characteristic ? Explain briefly.
(c) Derive the torque equation of SRM. (Switch Reluctance Motof)
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