A squirrel cage induction motor is not selected when
initial cost is the main consideration
maintenance cost is to be kept low
higher starting torque is the main consideration
all above considerations are involved
Q.3.
Less maintenance troubles are experienced in case of
slip ring induction motor
squirrel cage induction motor
both (a) and (b)
none of the above
Q.4.
In a squirrel cage motor the induced e.m.f. is
dependent on the shaft loading
dependent on the number of slots
slip times the stand still m.f. induced in the rotor
none of the above
Q.5.
The purpose of using short-circuit gear is
to short circuit the rotor at slip rings
to short circuit the starting resis¬tances in the starter
to short circuit the stator phase of motor to form star
none of the above
Q.6.
For driving high inertia loods best type of induction motor suggested is
slip ring type
squirrel cage type
any of the above
none of the above
Q.7.
Reduced voltage starter can be used with
slip ring motor only but not with squirrel cage induction motor
squirrel cage induction motor only but not with slip ring motor
squirrel cage as well as slip ring induction motor
none of the above
Q.8.
An induction motor can run at synchronous speed when
it is run on load
it is run in reverse direction
it is run on voltage higher than the rated voltage
m.f. is injected in the rotor circuit
Q.9.
The torque developed by a 3-phase induction motor least depends on
rotor current
rotor power factor
rotor m.f.
shaft diameter
Q.10.
In an induction motor if air-gap is increased
the power factor will be low
windage losses will be more
bearing friction will reduce
copper loss will reduce In an induction motor
Q.11.
Insertion of resistance in the rotcir of an induction motor to develop a given torque
decreases the rotor current
increases the rotor current
rotor current becomes zero
rotor current rernains same
Q.12.
When /?2 is tne rotor resistance, .X2 the rotor reactance at supply frequency and s the slip, then the condition for maximum torque under running condi-tions will be
sR2X2 = 1
sR2 = X2
R2 = sX2 i
R2 = s2X2
Q.13.
In case of a double cage induction motor, the inner cage has
high inductance arid low resistance
low inductance and high resistance
low inductance and low resistance
high inductance and high resis¬tance
Q.14.
Insertion of reactance in the rotor circuit
reduces starting torque as well as maximum torque
increases starting torque as well as maximum torque
increases starting torque but maxi-mum torque remains unchanged
increases starting torque but maxi-mum torque decreases
Q.15.
The torque of an induction motor is
directly proportional to slip
inversely proportional to slip
proportional to the square of the slip
none of the above
Q.16.
In a star-delta starter of an induction motor
resistance is inserted in the stator
reduced voltage is applied to the stator
resistance is inserted in the rotor
applied voltage per1 stator phase is 57.7% of the line voltage
Q.17.
Slip ring motor is preferred over squirrel cage induction motor where
high starting torque is required
load torque is heavy
heavy pull out torque is required
all of the above
Q.18.
A pump induction motor is switched on to a supplylower than its rated voltage.The pump runs. What will eventually happen ? It will
stall after sometime
stall immediately
continue to run at lower speed without damage
get heated and subsequently get damaged
Q.19.
AkW, 3-phase,volts,Hz, A.C. induction motor has a speed ofr.p.m. onfull load. The machine has 6 poles. The slip of the machine will be
0.01
0.02
0.03
0.04
Q.20.
What will happen if the relative speed between the rotating flux of stator and rotor ofthe induction motor is zero ?
The slip of the motor will be 5%
The rotor will not run
The rotor will run at very high speed
The torque produced will be very large
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