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

Question: Slip rings are usually made of___________?

• 1. copper
• 2. carbon
• 3. phospor bronze
• 4. aluminium

Question: In case the air gap in an induction motor is increased____________?

• 1. the magnetising current of the rotor will decrease
• 2. the power factor will decrease
• 3. speed of motor will increase
• 4. the windage losses will increase

Question: In squirrel cage induction motors, the rotor slots are usually given slight skew in order to__________?

• 1. reduce windage losses
• 2. reduce eddy currents
• 3. reduce accumulation of dirt and dust
• 4. reduce magnetic hum

Question: In medium sized induction motors, the slip is generally around___________?

• 1. 0.04%
• 2. 0.4%
• 3. 4%
• 4. 14%

Question: Which of the following component is usually fabricated out of silicon steel ?

• 1. Bearings
• 2. Shaft
• 3. Statorcore
• 4. None of the above