1. The number of slip rings in a 3-phase wound motor induction motor is
a) 3
b) 4
c) 6
d) 12
ans. a
2. The core of the rotor of a 3-phase induction motor
a) is always laminated
b) is solid
c) is sometimes laminated
d) none of these
ans. a
3. Under running condition the rotor circuit of a 3-phase induction motor is
a) always closed
b) always open
c) sometimes open and sometimes closed
d) none of these
ans. a
4. Under blocked rotor conditions, a 3-phase induction motor is similar to a transformer
a) with secondary open-circuited
b) with secondary under-loaded
c) with secondary short circuited
d) none of these
ans. c
5. Which of the following motors is used most frequently?
a) dc shunt motor
b) ac induction motor
c) 3-phase commutator rotor
d) 3-phase induction motor
ans. d
6. Which motor is widely used?
a) A squirrel cage induction motor
b) A slip-ring induction motor
c) A wound rotor synchronous motor
d) A salient pole synchronous motor
ans. a
7. An induction motor has a rated speed of 725 rpm. How many poles has its rotating magnetic field?
a) 2 poles
b) 4 poles
c) 6 poles
d) 8 poles
ans. d
8. Synchronous speed is defined as
a) The speed of the rotor of an induction motor
b) The speed of a synchronous motor
c) The speed of an induction motor at no-load
d) The natural speed at which a magnetic field rotates
ans. d
9. The direction of rotation of a 3-phase induction motor is reversed by
a) interchanging the connection of any two phases
b) interchanging the connection of all the 3 phases
c) rewinding the stator
d) adding a capacitor in any phase
ans. a
10. Which of the following is not a part of a squirrel cage induction motor?
a) Rotor
b) Stator
c) Carbon brushes
d) Shaft
ans. c
a) 3
b) 4
c) 6
d) 12
ans. a
2. The core of the rotor of a 3-phase induction motor
a) is always laminated
b) is solid
c) is sometimes laminated
d) none of these
ans. a
3. Under running condition the rotor circuit of a 3-phase induction motor is
a) always closed
b) always open
c) sometimes open and sometimes closed
d) none of these
ans. a
4. Under blocked rotor conditions, a 3-phase induction motor is similar to a transformer
a) with secondary open-circuited
b) with secondary under-loaded
c) with secondary short circuited
d) none of these
ans. c
5. Which of the following motors is used most frequently?
a) dc shunt motor
b) ac induction motor
c) 3-phase commutator rotor
d) 3-phase induction motor
ans. d
6. Which motor is widely used?
a) A squirrel cage induction motor
b) A slip-ring induction motor
c) A wound rotor synchronous motor
d) A salient pole synchronous motor
ans. a
7. An induction motor has a rated speed of 725 rpm. How many poles has its rotating magnetic field?
a) 2 poles
b) 4 poles
c) 6 poles
d) 8 poles
ans. d
8. Synchronous speed is defined as
a) The speed of the rotor of an induction motor
b) The speed of a synchronous motor
c) The speed of an induction motor at no-load
d) The natural speed at which a magnetic field rotates
ans. d
9. The direction of rotation of a 3-phase induction motor is reversed by
a) interchanging the connection of any two phases
b) interchanging the connection of all the 3 phases
c) rewinding the stator
d) adding a capacitor in any phase
ans. a
10. Which of the following is not a part of a squirrel cage induction motor?
a) Rotor
b) Stator
c) Carbon brushes
d) Shaft
ans. c
