Download AKTU B-Tech 4th Sem 2014-15 Electro Mechanical Energy Conversion Ii Question Paper

Download AKTU (Dr. A.P.J. Abdul Kalam Technical University (AKTU), formerly Uttar Pradesh Technical University (UPTU) B-Tech 4th Semester (Fourth Semester) 2014-15 Electro Mechanical Energy Conversion Ii Question Paper

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PAPER ID : 121409 '
Roll No.
B. Tech.
(SEM. IV) THEORY EXAMINATION, 2014-15
ELECTRO-MECHANICAL ENERGY CONVERSION - II
Time : 3 Hours] [Total Marks : 100
Note: ('1) Attempt All questions
('11) All questions carry equal marks.
1 Attempt any two parts. (10X2 = 20)
(a) Explain E.MF. equation cfAltemator. '
A 3-phase, 50 H7, 8-pole alternator has astar?connected
winding with 120 slots and 8 conductors per slot. The
?ux per pole is 0.05 Wb, sinusoidally distributed.
Determine the phase and line voltages.
(b) Sketch and explain the open?circuit and short-circuit
characteristics of a synchronous machine. How voltage
regulation can be calculated by the use of their results.
(c) Explain the Potier-triangle method of determining the
voltage regulation of an alternator.
121409] 1 l Contd...

2 Attempt any two parts.
(a)
(b)
(C)
3 Attempt any four parts.
(a)
(b)
(c)
(d)
(e)
(0
121409}
(10x2=20)
Explain the two reaction theogi applicable to silent?pole
synchronous machine.
Explain statting method of synchronous motor and its
working as synchronous condenser.
Explain hunting of a synchronous machine. What are
V-curves of a synchronous motor? ,
(5x4=20)
Explain the pn'nciple of Operation of a 3-phase induction
motor.
A 4-pole, 50 Hz induction motor runs with 4% slip at
full load.
What will be the frequency of current induced in the
rotor
' (1) A1 starting
(ii) At ?ill-load
Develop the equivalent circuit for a 3-phase induction
motor.
Sketch the torque-slip characteristics of a 3-phase
induction motor indicating there in the starting torque,
maximum torque and the operating region.
A 6-pole, 50 Hz induction motor runs with 5 percent
slip. What is its speed? What is the frequency of the
rotor current?
Explain the voltage build-up of an isolated induction
generator.
2 . [ Contd...
4 Attempt any two parts.
G?
(b)
?3
5 Attempt any two parts.
(a)
(b)
(C)
121409]
(10x2=20)
Explain the phenomenon of crawling and cogging in a
3-phase induction motor.
Discuss brie?y the various methods of spwd control
of 3phase induction motors.
If the outer cage has an equivalent impedance of (0.6
+ j0.6) ohm and the itmer cage an equivalent impedance
of (0.1 + j0.8) ohm both at supply frequency, calculate
the current and torque in Synchronous watts for the two
cages at standstill and at 10% slip. The e?'ective
standstill emf. of each cage is 200 V.
(10x2=20)
Why the l-phase induction motor is not self-starting?
Explain double revolving ?eld theory.
Eiqalain the operation of a stepper motor and state some
important application of stepper motors.
Explain starting methods of l-phase induction motor.
What is Repulsion motor?
3 [6325]