The torque angle, in a synchronous motor, is the angle between_______________?
(A) the supply voltage and the back e.m.f.
(B) magnetising current and back e.m.f.
(C) the rotating stator flux and rotor poles
(D) none of the above
A 3-phase synchronous motor is running clockwise. If the direction of its field current is reversed
(A) the motor will stop
(B) the motor continue to run in the same direction
(C) the winding of the motor will burn
(D) the motor will run in the reverse direction
(D) none of the above
The net armature voltage of a synchronous motor is equal to the_______________?
(A) vector sum of Eb and V
(B) arithmetic sum of Eb and V
(C) arithmetic difference of Eb and V
(D) vector difference of Eh and V
In a synchronous motor, damper windings are provided on____________?
(A) stator frame
(B) rotor shaft
(C) pole faces
(D) none of the above
In a 3-phase synchronous motor, the negative phase sequence exists when the motor is_______________?
(A) supplied with unbalanced voltage
(B) under-loaded
(C) over-loaded
(D) none of the above
Due to which of the following reasons a synchronous motor fails to pull into synchronism after applying D.C. field current?
(A) High field current
(B) Low short circuit ratio
(C) High core losses
(D) Low field current
The construction of a synchronous motor resembles____________?
(A) a series motor
(B) an induction motor
(C) an alternator
(D) a rotary converter
For power factor correction, synchronous motors operate at____________?
(A) no-load and greatly over-excited fields
(B) no-load and under-excited fields
(C) normal load with minimum excitation
(D) normal load with zero excitation
Which of the following losses is not dissipated by the stator core surface in a synchronous motor?
(A) Eddy current losses in the conductors
(B) Iron losses in the stator
(C) Copper losses in the slot portion of the conductors
(D) Windage losses
(D) None of the above
The size of a synchronous motor decreases with the increase in___________?
(A) flux density
(B) horse power rating
(C) speed
(D) all of the above