A synchronous machine is operating at constant load and at unity power factor. If its excitation is increased, then it operates as

Consider a 3-phase cylindrical-rotor alternator
A. E.m.f. generated by armature reaction lags armature current by 90°.
B. Air gap voltage leads the field flux by 90°
C. Air gap voltage lags the field flux by 90°
D. Armature reaction due to intermediate lagging p.f. is partly cross magnetizing and partly magnetizing

Power factor of a synchronous motor varies when

Rating of the dc motor to be used in the starting of SM, should be higher than the synchronous motor.

A 3-phase, 400V, synchronous motor is providing load at 0.8 p.f. lagging. If the field current of the motor is continuously increased, then

A synchronous machine with its field winding on stator and polyphase armature winding on rotor.At steady state, which of the following is not true for its air gap field

Consider the following statements and mark appropriately
I. In a cylindrical-rotor synchronous machine, armature flux is in phase with armature current.
II. In salient pole machine, armature flux lags the armature current.

In a 3-phase cylindrical-rotor alternator, synchronous reactance is sum of mutual and leakage reactance.

I. Auxiliary motor
II. Dc motor
III. induction motor
The method is/are used to perform magnetic locking

The reactive power output of a synchronous generator is limited by

Auxiliary method of starting is not possib1e due to the fact that

A synchronous machine with its field winding on rotor and polyphase armature winding on stator. At steady state running condition, its air gap field is
I. stationary w.r.t. stator
II. rotating at double the Ns w.r.t. rotor
III. rotating at -Ns w.r.t. rotor
IV. stationary w.r.t. rotor.

These days alternators are designed to have larger air gaps for

Synchronous motors are

A synchronous machine is operating at constant load and at unity power factor.
If its excitation is increased and then it operates as