. In a synchronous motor which loss varies with load ?
(A) Windage loss
(B) Bearing friction loss
(C) Copper loss
(D) Core loss
For V-curves for a synchronous motor the graph is drawn between:_______________?
(A) armature current and power factor
(B) terminal voltage and load factor
(C) power factor and field current
(D) field current and armature current
The synchronous motor is not inherently self-starting because_______________?
(A) the force required to accelerate the rotor to the synchronous speed in an instant is absent
(B) the starting device to accelerate the rotor to near synchronous speed is absent
(C) a rotating magnetic field does not have enough poles
(D) the rotating magnetic field is produced by only 50 Hz frequency currents
When V is the applied voltage, then the breakdown torque of a synchronous motor varies as_________?
(A) V
(B) V312
(C) V2
(D) 1/V
A three-phase synchronous motor will have_____________?
(A) no slip-rings
(B) one slip-ring
(C) two slip-rings
(D) three slip-rings
Which of the following resistances can be measured by conducting insulation resistance test on a synchronous motor ?
(A) Phase to phase winding resistance
(B) Stator winding to earthed frame
(C) Rotor winding to earthed shaft
(D) All of the above
The speed of a synchronous motor:
(A) increases as the load increases
(B) decreases as the load decreases
(C) always remains constant
(D) none of the above
When a 3-phase synchronous generator is supplying a zero power factor lagging load, the armature field affects the main field in the following way
(A) augments it directly
(B) directly opposes it
(C) cross-magnetises it
(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
Change of D.C. excitation of a synchronous motor changes:
(A) applied voltage of the motor
(B) power factor of power drawn by the motor
(C) motor speed
(D) none of the these
(D) all of the these