## Induction Motor important questions-Electrical Engineering, Three-phase induction motor important questions for Electrical Engineering students.

#### List of 25 important questions about Induction motor

1) In an induction motor, rotor slots are usually not quite parallel to the salt nut arc given a slight skew for the reason: to reduce the magnetic hum and the locking tendency of the rotor

2) In an induction motor, rotor runs as a speed: lower than the speed of stator field

3) When an induction motor runs at rated load and speed, the iron losses are: negligible

4) The starting torque of an induction motor is maximum when: rotor resistance equals rotor reactance

5) Wattmeter reading in no-load test induction motor gives: total losses in the rotor on no load

6) At zero slip is an induction motor: motor does not run

7) Increase in the air gap flux density in an induction motor result in: increased iron loss and decreased efficiency

8) The rotor of a 3-phase induction motor receives energy from: inverted do supply

9) When the rotor of a 3-phase induction motor runs at synchronous speed, the rotor: current, torque and emf are zero

10) Torque developed by a three-phase induction motor equals: power input to rotor minus rotor losses

11) The direction of rotation of a three-phase: interchanging the connection of a two phases

12) A 3-phase induction motor running at 1400rpm on rated supply will run at the following rpm when a fuse of one phase gets burnt: 1380 rpm

13) A three-phase 6 pole 50Hz induction motor works with 5% slip. The actual speed of the motor is: 950 rpm

14) The field winding of a three-phase synchronous machine is excited: dc supply

15) If in a 3-phase induction motor, Two phases open accidentally, the motor will: continue to run depending on load

16) A 4-pole 50Hz induction motor normally runs at a speed of: 1440 rpm

17) Squirrel cage induction motor has: very small starting torque

18) The advantage of double squirrel cage rotor as compared to the round bar cage rotor: lower starting torque

19) On open circuiting, the rotor of a squirrel cage induction motor, rotor: does not run

20) External resistance can be added to start the motor: slip ring induction motor

21) An induction motor has a rated speed of 715 rpm. The number of poles in its rotating magnetic field equals: 4 poles

22) For 4% drop in supply voltage, the torque of an induction motor increased by: 16%

23) Improvement of the power factor in an induction motor results in: increased torque and decreased current due to increased impedance

24) The function is served by the resistance placed in parallel with one phase of three-phase induction motor: smooth starting

25) The rotor output of an induction motor is 15kW and the slip is 4%. Then the rotor copper loss is: 600 watts