23- What is the value in terms of degrees electrical for maximum torque angle in a synchronous machine?
(A) 45
(B) 90
(C) below 60
(D) between 45 and 90
24- In a squirrel cage induction motor, the rotor slots are usually given a slight skew in order to
(A) Reduce the windage loss
(B) Reduce eddy current loss.
(C) Reduce accumulation of dirt and dust.
(D) Reduce magnetic hum
25- In order to provide high starting torque in a double squirrel cage induction motor,
(A) The resistance of the outer cage winding is high and that of the inner cage winding is low
(B) The resistance of the outer cage winding is low and that of the inner cage winding is high
(C) The resistance of the outer and inner cage winding is low
(D) The resistance of the outer and inner cage winding is high.
26- Starting winding of the single phase induction motor is placed in the
(A) rotor
(B) stator
(C) armature
(D) field
27- The direction of rotation of a synchronous motor can be reversed by reversing
(A) current to the field winding
(B) supply phase sequence
(C) polarity of rotor poles
(D) none of the above
28- The fractional slip of an induction motor is determined from the ratio
(A) rotor copper loss to rotor input
(B) rotor copper loss to rotor output
(C) rotor copper loss to stator input
(D) rotor copper loss to stator output
29- In a 3-Phase induction motor, the rotor field rotates at synchronous speed with respect to
(A) Stator
(B) Rotor
(C) Stator flux
(D) None of the above
30- Which of the following sentences is true for squirrel-cage induction motor?
(A) Power factor is low at heavy load only
(B) Power factor is low at light loads only
(C) Power factor is low both at light and heavy loads
(D) Power factor is low at rated load only
31- The reason why starters are used in Induction motor is ___
(A) It cannot run in reverse direction
(B) Its starting current is five times or more than its rated current
(C) It can run in reverse direction
(D) It is run against heavy load
32- An induction motor is identical to
(A) Asynchronous motor
(B) D.C. compound motor
(C) D.C. series motor
(D) Synchronous motor
33- When we can use synchronous motor as a synchronous capacitance?
(A) Under loaded
(B) Overloaded
(C) Over excited
(D) Under exited
34- When the voltage applied to a synchronous motor is increased, which of the following will reduce?
(A) Stator flux
(B) Pull in torque
(C) Both A and B
(D) None of these
ANSWERS:
23-(B), 24-(D), 25-(A), 26-(B), 27-(B), 28-(A), 29-(A), 30-(B), 31-(B), 32-(A), 33-(C), 34-(D)