In the circle diagram for induction motor, the diameter of the circle represents____________?
A. slip
B. rotor current
C. running torque
D. line voltage
Polyphase Induction Motors
Stepless speed control of induction motor is possible by which of the following methods ?
Stepless speed control of induction motor is possible by which of the following methods ?
A. e.m.f. injection in rotor eueuit
B. Changing the number of poles
C. Cascade operation
D. None of the above
It is advisable to avoid line-starting of induction motor and use starter because__________?
It is advisable to avoid line-starting of induction motor and use starter because__________?
A. motor takes five to seven times its full load current
B. it will pick-up very high speed and may go out of step
C. it will run in reverse direction
D. starting torque is very high
When the equivalent circuit diagram of doouble squirrel-cage induction motor is constructed the two cages can be considered__________?
When the equivalent circuit diagram of doouble squirrel-cage induction motor is constructed the two cages can be considered__________?
A. in series
B. in parallel
C. in series-parallel
D. in parallel with stator
The torque developed in the cage induction motor with autostarter is___________?
The torque developed in the cage induction motor with autostarter is___________?
A. k/torque with direct switching
B. K x torque with direct switching
C. K2 x torque with direct switching
D. k2/torque with direct switching
The auto-starters (using three auto transformers) can be used to start cage induction motor of the following type__________?
The auto-starters (using three auto transformers) can be used to start cage induction motor of the following type__________?
A. star connected only
B. delta connected only
C. A. and B. both
D. none of the above
The crawling in the induction motor is caused by____________?
The crawling in the induction motor is caused by____________?
A. low voltage supply
B. high loads
C. harmonics develped in the motor
D. improper design of the machine
E. none of the above
Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor _____________?
Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor _____________?
A. By changing the number of stator poles
B. Rotor rheostat control
C. By operating two motors in cascade
D. By injecting e.m.f. in the rotor circuit
An induction motor is identical to_________?
An induction motor is identical to_________?
A. D.C. compound motor
B. D.C. series motor
C. synchronous motor
D. asynchronous motor
The injected e.m.f. in the rotor of induction motor must have__________?
The injected e.m.f. in the rotor of induction motor must have__________?
A. zero frequency
B. the same frequency as the slip frequency
C. the same phase as the rotor e.m.f.
D. high value for the satisfactory speed control