Download AKTU B-Tech 6th Sem 2014-2015 Introduction To Electric Drives Question Paper

Download AKTU (Dr. A.P.J. Abdul Kalam Technical University (AKTU), formerly Uttar Pradesh Technical University (UPTU) B-Tech 6th Semester (Sixth Semester) 2014-2015 Introduction To Electric Drives Question Paper

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(Following Paper I!) and Roll No. to be ?lled in your Answer Book)
PAPER ID : 131604
Roll No.
(SEM. VI) THEORY EXAMINATION, 2014-15
INTRODUCTIOl?i TO ELECTRIC DRIVES
Tune : 2 Hours] ? [Total Marks : 50 ,
l ? Attempt any two pans : ? 2X5=10 .
(a). Explain the variqus terms involved in turn on and
turn o??time of SCR; in dynamic characteristics.
Why circuit tum o?? time 'is kept larger ?
(b) De?ne di/dt and dv/dt protection of sons. What
are the components used to protect SCR ?7
(c). . Give various uiggedng methods in SCR Explain
? in detail pulse mpggering method and requisite
2 Attempt any two pans of the following : ZXS=10
(a) Den've the exprwsin of a l?phase full wave bridge
recti?er fully contolledfdf'kLE load and also
draw the requisite waveforms.
131504]; 1 _ [ Contd...

(b)
(o)
(a)
(b)
(c)
(a)
131604]
Attempt any twoparts of the following :
Attempt any two parts. of the following :
Explain the opemtion oftlmee phase halfoomrolled
?ill wave recti?er with desired waveforms.
Explain control strategies of chopper with respect
to step down chopper. Also classify and explain
the choppers according to quadrant operation.
Give the difference between 180? and 120?
modes of three phase inverter with relevant
waveforms of ? phase and line voltages.
Explain the basic' principle Vof step down
cyclooonvetter. '
'Write short notes on following :
(1) Series inverter
(11') Jones chopper
(ii) 3-? to 3-45 step down cyclooonverter.
(1v) Power factor improvement in do drives.
(v) ?Self control scheme of synchronous motor
The speed of separately?excited dc motor is
controlled through 1-phase halfwave eontrdlled
??om230Vmins.Themotorammure1-wistme
is 0.5 Ohm and motor constant is K = 0.4 V-
s/rad/for load torque of 20 Nm at lSOO-rpm and
for constant armature current, calculate :
(i) Filing angle of converter.
(ii) RMS value of thytistor current.
(in) UP power factor of the motor.
2
2X5=10
2X5=10
[ Contd...
(b) Descnhe the regenerative breaking ofchopper fed
wpm'ately excited dc motor. Illustrate the answer
with circuit diagram and relevant waveforms.
(c) De?ne the basic principle of operation of cyclo-
convelter. Explain the working of l-phase and 3-
pimse cycloconverter.
5 Attempt any two parts of the following : 2x5=10
(9.) Explain four quadrant chopper d?i/es. Explain
three phase semiconductor drives.
(b) Enumerate the various methods of speed control
of 3-phase induction motor when fed through
semiconductor devices.
(c) Describe the Kama drive and show that steady
state torque is not in?uenced by whether a
transformer is used or not ?
131604] 3 [ 3450 ]