In a synchronous motor, the damping winding is generally used to______________?

A. Reduce nosie level
B. Reduce the eddy currents
C. Provide starting torque only
D. Prevent hunting and provide the starting torque

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

In a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole number and load torque all are halved. The motor speed will be____________?

A. 3000 r.p.m.
B. 1500 r.p.m.
C. 750 r.p.m.
D. None of the above

In a synchronous motor, V-curves represent relation between____________?

A. Armature current and field current
B. Power factor and speed
C. Field current and speed
D. Field current and power factor

By which of the following methods the constant speed of a synchronous motor can be changed to new fixed value ?

A. By changing the supply frequency
B. By interchanging any two phases
C. By changing the applied voltage
D. By changing the load

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

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