Which of the following losses, in a synchronous motor, does not vary with load?
(A) Windage loss
(B) Copper losses
(C) Any of the above
(D) None of the above
In a synchronous motor, the armature current has large values for____________?
(A) high excitation only
(B) low excitation only
(C) both high and low excitation
(D) none of the above
The back e.m.f. in the stator of a synchronous motor depends on____________?
(A) number of poles
(B) flux density
(C) rotor speed
(D) rotor excitation
(D) none of the above
If the field of a synchronous motor is underexcited, the power factor will be_____________?
(A) zero
(B) unity
(C) lagging
(D) leading
In a synchronous motor, the damping winding is generally used to______________?
(A) reduce noise level
(B) reduce the eddy currents
(C) provide starting torque only
(D) prevent hunting and provide the starting torque
(D) none of the above
In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then
(A) the motor is said to be fully loaded
(B) the torque generated is maximum
(C) the excitation is said to be zero per cent
(D) the excitation is said to be hundred per cent
A synchronous motor can develop synchronous torque:
(A) when under loaded
(B) while over-excited
(C) only at synchronous speed
(D) below or above synchronous speed
The maximum power developed in a synchronous motor will depend on__________?
(A) the rotor excitation only
(B) the supply voltage only
(C) the rotor excitation and supply volt-age both
(D) the rotor excitation, supply voltage and maximum value of coupling angle (90°)
(D) none of the above
In a synchronous motor, the breakdown torque is__________?
(A) directly proportional to the square of the applied voltage
(B) directly proportional to applied voltage
(C) inversely proportional to applied voltage
(D) none of the above
A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as_________?
(A) static condenser
(B) condenser
(C) synchronous condenser
(D) none of the above