Question: The crawling in the induction motor is caused by____________?

• 1. low voltage supply
• 2. high loads
• 3. harmonics develped in the motor
• 4. improper design of the machine

Question: Which of the following methods is easily applicable to control the speed of the squirrel-cage induction motor _____________?

• 1. By changing the number of stator poles
• 2. Rotor rheostat control
• 3. By operating two motors in cascade
• 4. By injecting e.m.f. in the rotor circuit

Question: An induction motor is identical to_________?

• 1. DC compound motor
• 2. DC series motor
• 3. synchronous motor
• 4. asynchronous motor

Question: The injected e.m.f. in the rotor of induction motor must have__________?

• 1. zero frequency
• 2. the same frequency as the slip frequency
• 3. the same phase as the rotor e.m.f.
• 4. high value for the satisfactory speed control

Question: In case of the induction motors the torque is___________?

• 1. inversely proportional to (Vslip)
• 2. directly proportional to (slip)2
• 3. inversely proportional to slip
• 4. directly proportional to slip

Question: The good power factor of an induction motor can be achieved if the average flux density in the air gap is___________?

• 1. absent
• 2. small
• 3. large
• 4. infinity

Question: A double squirrel-cage induction motor has______________?

• 1. two rotors moving in oppsite direction
• 2. two parallel windings in stator
• 3. two parallel windings in rotor
• 4. two series windings in stator

Question: Star-delta starting of motors is not possible in case of____________?

• 1. single phase motors
• 2. variable speed motors
• 3. low horse power motors
• 4. high speed motors

Question: The starting torque of a squirrel-cage induction motor is___________?

• 1. low
• 2. negligible
• 3. same as full-load torque
• 4. slightly more than full-load torque

Question: In Ns is the synchronous speed and s the slip, then actual running speed of an induction motor will be___________?

• 1. Ns
• 2. s.N,
• 3. (l-s)Ns
• 4. (Ns-l)s