3 Phase Induction Motor MCQ With Answer -1

1. Who is connected to the source in A.C. motors?
(A) rotor
(B) Stator
(C) both
(D) None
Answer- (B)

2. The rotation speed in the AC motor is respectively proportional and inversely proportional?
(A) Frequency and Poll
(B) back emf
(C) both
(D) None
Answer- (A)

3. What is the main type of A.C. motor?
(A) five
(B) both
(C) three
(D) six
Answer- (B)

4. What type of magnetic field is produced when the stator is supplied?
(A) rotating
(B) stable
(C) both
(D) None
Answer- (A)

5 What is the minimum requirement to obtain a rotating visible magnetic field?
(A) Single phase
(B) Three Phase
(C) two phase
(D) All of the above
Answer- (C)

6 What is the speed of rotation of a rotating magnetic field?
(A) rotor speed
(B) stator speed
(C) synchronous speed
(D) armature speed
Answer- (C)

7 What is the formula to find synchronous speed?
(A) Ns = 120f / P
(B) Ns = 120P / f
(C) Ns = 120f / t
(D) None
Answer- (A)

8. Rotational speed of rotor is always-
(A) Less than rotor speed
(B) less than stator speed
(C) less synchronous speed
(D) less than armature speed
Answer- (C)

9 The formula for determining the slip of a motor is (in percentage).

(A) S=((Ns-Nr)/Ns)X100

(B) S=((Ns-Ns)/Nr)X100

(C) S= (Nr)/(Ns-Ns)X100

(D) Non of the above
Answer- (A)

10 Most of the squirrel cage motor has a slip percentage.
(A) 2 to 5%
(B) 1 to 5%
(C) 2 to 7%
(D) 2 to 8%
Answer- (A)

11 is the formula to find the rotor frequency
(A) Fr = SXT
(B) Fr = SXZ
(C) Fr = SXV
(D) Fr = SXF
Answer- (D)

12. What is torque?
(A) rotational force received at load
(B) Rotation force received on the shaft
(C) Rotation force received on the rotor
(D) All of the above
Answer- (A)

13 Induction motor's torque is calculated
(A) D.C. Like a motor
(B) A.C. Like a motor
(C) Like synchronous motor
(D) Like stepper motor
Answer- (A)

14 What is difficult to find in an induction motor
(A) Stator magnetic flux
(B) induced rotor current
(C) both
(D) None
Answer- (C)

15 What is done to get torque in an induction motor?
(A) Resistor in series of rotor
(B) resistor parallel to the rotor
(C) both
(D) None
Answer- (A)

16 Squirrel Cage Motor consists mainly of how many parts?
(A) 5
(B) 2
(C) 3
(D) 4
Answer- (B)

17. Three phase motor is the angle between the windings
(A) 90 degrees
(B) 100 degrees
(C) 45 degrees
(D) 120 degrees
Answer- (D)

18 Which motor has six connective ends on its terminal box.
(A) Squirrel Cage
(B) slip rig
(C) both
(D) None
Answer- (C)

19. Why are the chalk made to be fixed in a single cage rotor?
(A) Keeping the magnetic field equal
(B) Keeping torque equal
(C) both
(D) None
Answer- (C)

20. The outer layer of double cage rotor is made of low resistance metal (copper).
(A) More resistance (iron)
(B) More resistance (steel)
(C) More resistance (Carbon)
(D) More resistance (Brass)
Answer- (D)