Objective Questions on Single Phase Motors

31. The type of starting relay used on single phase hermetic motor is

(A) hot wire relay
(B) timing relay
(C) current coil relay
(D) voltage coil relay
(E) any of the above.

32. Reluctance motors are

(A) doubly excited
(B) singly excited
(C) either doubly excited or singly excited
(D) none of the above.

33. Electric motors are generally designed to have maximum efficiency at

(A) full load
(B) near full load
(C) half load
(D) near half load.

34. Which of the following is non-reversible motor ?

(A) Universal motor
(B) Capacitor start split phase motor
(C) Resistance start split phase motor
(D) Permanent split capacitor motor.

35. Which motor is generally used for electric shavers ?

(A) Shaded pole motor
(B) Hysteresis motor
(C) Reluctance motor
(D) Universal motor.

36. The motor useful for signaling and timing device is

(A) Reluctance motor
(B) Shaded pole motor
(C) Hysteresis motor
(D) Two value capacitor motor.

37. A motor generally used in toys is

(A) Hysteresis motor
(B) Shaded pole motor
(C) Two value capacitor motor
(D) Reluctance motor.

38. Single phase motors generally get over heated due to

(A) Overloading
(B) Short windings
(C) Bearing troubles
(D) Any of the above.

39. Which of the following is a reversible motor ?

(A) Universal motor
(B) Capacitor start split phase motor
(C) Both (A) and (B) above
(D) None of the above.

40. The starting torque of a single phase induction motor is

(A) uniform
(B) high
(C) low
(D) zero.

41. Which of the following motors will operate at high power factor ?

(A) Universal motor
(B) Capacitor start motor
(C) Capacitor run motor
(D) Split phase motor.

42. Which of the following statements about reluctance motor is not true ?

(A) It is self starting
(B) It runs at constant speed
(C) It needs no dc excitation for its rotor
(D) It can operate on ac as well as dc.

43. The rotor for a hysteresis motor

(A) is made of chrome steel
(B) has high retentivity
(C) has high hysteresis loss
(D) should have all above properties.

44. The speed of a universal motor can be controlled by

(A) introducing a variable resistance in series with the motor
(B) tapping the field at various points
(C) centrifugal mechanisms
(D) any of the above.

45. What could be the smallest size of a universal motor?

(A)1/10 HP
(B)1/20 HP
(C)1/20 HP
(D)1/2000 HP.