Related Questions

A synchronous motor installed at the receiving end substation operates with such an excitation that it takes power at lagging power factor. Now if the applied voltage of the synchronous motor goes down, the power factor of the synchronous motor will
A remain same
B go down
C improve
D none of the above
The coupling angle or load angle of synchronous motor is defined as the angle between the
A rotor and stator teeth
B rotor and the stator poles of opposite polarity
C rotor and the stator poles of the same polarity
D none of the above
The power developed by a synchronous motor will be maximum when the load angle is
A zero
B 45°
C 90°
D 120°
A synchronous motor is running on a load with normal excitation. Now if the load on the motor is increased
A power factor as well as armature current will decrease
B power factor as well as armature current will increase
C power factor will increase but armature current will decrease
D power factor will decrease and armature current will increase
If in a synchronous motor, driving a given mechanical load and drawing current at a leading power factor from constant voltage supply its field excitation is increased, its power factor
A will become more
B will become less
C will remain unchanged
D none of the above.
If in a synchronous motor, driving mechanical load and drawing current at lagging power factor from constant voltage supply, its field excitation is increased, then its power factor
A become more
B become less
C remain constant
D none of the above
The maximum power developed in a synchronous motor occurs at a coupling angle of
A 30°
B 60°
C 90°
D 180°
In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will
A Become unstable
B Draw excessive armature current and may burn out
C Fall out of synchronism and come to stand still
D Run as induction motor
As the load is applied to a synchronous motor, the motor takes more armature current because
A The increased load has to take more current
B The rotor by shifting its phase backward causes motor to take more current
C The back e.m.f. decreases causing an increase in motor current
D The rotor strengthens the rotating field causing more motor current
A synchronous motor can be used as a synchronous capacitor when it is
A under-loaded
B over-loaded
C under-excited
D over-excited

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