Deemed University 2009 A.M.I.E.T.E Electronics

AMIETE – ET (OLD SCHEME)

Code: AE26 Subject: POWER ELECTRONICS
Time: three Hours Max. Marks: 100

NOTE: There are nine ques. in all.
· ques. one is compulsory and carries 20 marks. ans to Q. 1. must be written in the space given for it in the ans book supplied and nowhere else.
· Out of the remaining 8 ques. ans any 5 ques.. every ques. carries 16 marks.
· Any needed data not explicitly given, may be suitably presumed and said.


Q.1 select the accurate or the best option in the following: (210)

a. GTO can be turned off by

(A) Applying a negative gate signal.
(B) Applying a positive gate signal.
(C) Reducing the current beneath holding current.
(D) Both (A) and (C).

b. DIACs are primarily used as

(A) Power thyristors. (B) Triggering devices.
(C) Surge protection devices. (D) Both (B) and (C).


c. Latching current of thyristor is associated with:

(A) Turn on process. (B) turn-off process.
(C) Turn-on and turn off process. (D) None of these.

d. A dual converter used for the speed control of dc motors, will have 2 bridges, they are

(A) 2 rectifiers. (B) 2 inverters.
(C) 1 rectifier and 1 inverter. (D) None of above.

e. A free wheeling diode is used in a controlled rectifier circuit in case of


(A) Resistive load. (B) Inductive load.
(C) Capacitive load. (D) None of above.

f. When energy is returned to the system by a motor, it is referred as


(A) Plugging. (B) Dynamic braking.
(C) Regenerative braking. (D) Reciprocating.

g. If the duty cycle of a chopper circuit is exactly 50%, the pulse is considered to be a:


(A) sine wave. (B) low duty cycle.

Earning:   Approval pending.