1) A self excited d.c
shunt generator, driven by its prime mover at the rated speed fails to build up
the voltage across its terminals at no load. What reason can be assigned for
this? (IES 2006)
a) The initial shunt
field mmf does not assist the residual magnetism
b) The field circuit
resistance is higher than the critical resistance
c) One of the
inter-pole connection is removed
d) Brush axis slightly
shift from the geometrical neutral axis of the machine
2) Wave winding is
employed in a dc machine of: (IES 2006)
a) High current and low
voltage rating
b) Low current and high
voltage rating
c) High current and
high voltage rating
d) Low current and low
voltage rating
3) The resultant flux
density in the air gap of a synchronous generator is the lowest during: (IES
2006)
a) Open circuit
b) Solid short circuit
c) Full load
d) Half load
4) If the load of an
Induction motor is increased from no load to full load, its slip and the power
factor will respectively (IES 2006)
a) decrease, decrease
b) decrease, increase
c) increase, decrease
d) increase, increase
5) A single phase
Induction motor is running at N rpm. Its synchronous speed is Ns. If its slip
with respect to forward field is 's', what is the slip with respect to the
backward field is: (IES 2006)
a) s
b) -s
c) (1-s)
d) (2-s)
6) Match the following: (IES 2003)
List I
List II
A. DC Motor 1. Circle Diagram
B. DC Generator 2. V-Curves
C. Alternator 3. Open circuit
characteristics
D. Induction Motor 4.Speed-Torque characteristics
Codes:
A B C D
a) 4 3 1 2
b) 3 4 2 1
c) 4 3 2 1
d) 3 4
1 2
7) A smaller air gap in a polyphase induction
motor helps to: (IES 2004)
a) reduces the chances
of crawling
b) Increases the
starting torque
c) reduces the chances
of cogging
d) reduce the
magnetising current
8) If the supply
voltage of the induction motor is reduced by 10%. By what percentage
approximately will the maximum torque decreases? (IES 2004)
a) 5%
b) 10%
c) 20%
d) 40%
Answers:
(1) b (2) b (3) b (4) d
(5) d (6) c (7) d (8) c
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