The injected e.m.f. in the rotor of induction motor must have
the same frequency as the slip frequency
zero frequency
the same phase as the rotor e.m.f.
high value for the satisfactory speed control
the same frequency as the slip frequency
The crawling in the induction motor is caused by
improper design of the machine
high loads
low voltage supply
harmonics developed in the motor
harmonics developed in the motor
The auto-starters (using three auto transformers) can be used to start cage induction motor of the following type
star connected only
delta connected only
and both
none of the above
and both
The shaft of an induction motor is made of
carbon steel
cast iron
stainless steel
high speed steel
carbon steel
In the circle diagram for induction motor the diameter of the circle represents
rotor current
running torque
slip
line voltage
rotor current
For which motor the speed can be controlled from rotor side ?
None of the above
Slip-ring induction motor
Squirrel-cage induction motor
Both and (2)
Slip-ring induction motor
DOL starting of induction motors is usually restricted to
low horsepower motors
variable speed motors
high horsepower motors
high speed motors
low horsepower motors
The speed of a squirrel-cage induction motor can be controlled by all of the following except
reducing supply voltage
changing number of poles
changing supply frequency
changing winding resistance
changing winding resistance
Size of a high speed motor as compared to low speed motor for the same H.P. will be
bigger
same
smaller
any of the above
smaller
A 3-phase induction motor stator delta connected is carrying full load and one of its fuses blows out. Then the motor
will continue running burning its one phase
will continue running without any harm to the winding
will stop and carry heavy current causing permanent damage to its winding
will continue running burning its two phases
will continue running burning its one phase
पोस्ट अच्छी लगी हो तो प्लीज नीचे दिए गए लिंक पर क्लिक कर शेयर जरुर करें
0 Comments