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___________?
(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 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
(D) none of the above
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
(D) m.f. in the rotor circuit
The ‘cogging’ of an induction motor can be avoided by____________?
(A) proper ventilation
(B) using DOL starter
(C) auto-transformer starter
(D) having number of rotor slots more or less than the number of stator slots (not equal)
The power factor of an induction motor under no-load conditions will be closer to_____________?
(A) 0.2 lagging
(B) 0.2 leading
(C) 0.5 leading
(D) unity
The ‘crawling” in an induction motor is caused by___________?
(A) high loads
(B) low voltage supply
(C) improper design of machine
(D) harmonics developed in the motor
The speed of a squirrel-cage induction motor can be controlled by all of the following except_____________?
(A) changing supply frequency
(B) changing number of poles
(C) changing winding resistance
(D) reducing supply voltage
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
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 in stator
(C) less than number of poles in stator
(D) equal to number of poles in stator