1.
The frame of an induction motor is usually made
of
a)
silicon steel
b) cast iron
c)
aluminium
d)
bronze
2.
The shaft of an induction motor is made of
a)
high speed steel
b)
stainless steel
c) carbon steel
d)
cast iron
3.
Slip rings are usually made of
a)
copper
b)
carbon
c) phosphor bronze
d)
aluminium
4.
The starting torque of a squirrel-cage induction
motor is
a) Iow
b)
negligible
c)
same as full-load torque
d)
slightly more than full-load torque
5.
An induction motor is identical to
a)
D.C. compound motor
b)
D.C. series motor
c)
synchronous motor
d) asynchronous motor
6.
If any two phases for an induction motor are
interchanged
a) the motor will run in reverse direction
b)
the motor will run at reduced speed
c)
the motor will not run
d)
the motor will burn
7.
An induction motor is
a)
self-starting with zero torque
b)
self-starting with high torque
c) self-starting with low torque
d)
non-self-starting
8.
In a three-phase induction motor, the number of
poles in the rotor winding is always
a)
zero
b)
more than the number of poles ¡n stator
c)
less than number of poles ¡n stator
d) equal to number of poles in stator
9.
DOL starting of induction motors is usually
restricted to
a) low horsepower motors
b)
variable speed motors
c)
high horsepower motors
d)
high speed motors
10.
Which type of bearing is provided in small
induction motors to support the rotor shaft?
a) Ball bearings
b)
Cast iron bearings
c)
Bush bearings
d)
None of the above
11.
A 3-phase slip ring motor has
a)
double cage rotor
b) wound rotor
c)
short-circuited rotor
d)
any of the above
12.
An induction motor can run at synchronous speed
when
a)
it is run on load
b)
it is run in reverse direction
c)
it is run on voltage higher than the rated
voltage
d) em.f is injected in the rotor circuit
13.
In an induction motor if air-gap is increased
a) the power factor will be low
b)
windage losses will be more
c)
bearing friction will reduce
d)
copper loss will reduce In an induction motor
14.
The torque of an induction motor is
a) directly proportional to slip
b)
inversely proportional to slip
c)
proportional to the square of the slip
d)
none of the above
15.
The starting torque of a three phase induction
motor can be increased by
a)
increasing slip
b)
increasing current
c) both (a) and (b)
d)
none of the above
16.
The efficiency of an induction motor is about
a)
100%
b) 80-90%
c)
50-60%
d)
Less than 50%
17.
The good power factor of an induction motor can
be achieved if the average flux density in the air gap is
a)
Infinity
b)
Large
c)
Absent
d) Small
18.
In three-phase squirrel-cage induction motors -
a)
Rotor conductors are kept open
b)
Rotor conductor ends are short-circuited through
slip rings
c) Rotor conductors are short-circuited through
end rings
d)
Rotor conductors are connected to insulation
19.
Which of the following motor has high starting
torque?
a) Slip ring Induction motor
b)
Squirrel cage induction motor
c)
Both (a) & (b)
d)
None of the above
20.
As compared to DOL starting method the star delta
starting method should have -
a)
High torque
b) Low starting current
c)
High starting current
d)
Smooth acceleration
21.
For starting of an induction motor, star/delta
starting can be considered equivalent to an autotransformer starter with the
ratio of
a)
3 3.3%
b)
50%
c)
100%
d) 57.7%
22.
No load test of 3-phase induction motor used to
determine
a)
Variable loss
b) Constant loss
c)
Eddy current loss only
d)
Hysteresis loss only
23.
In an induction motor, rotor speed is always
a) Less than the stator speed
b)
More than the stator speed
c)
Equal to the stator speed
d)
None of these
24.
In 3-phase induction motor, the rotor speed is
_____ the synchronous speed.
a)
Greater than
b) Small than
c)
Equal to
d)
None of these
25.
The Stator of a 3 phase induction motor produces
______ magnified field.
a)
steady
b) rotating
c)
alternating
d)
None of these