# In a synchronous motor, the armature current has large values for?

## 1 Answer

In a synchronous motor, the armature current has large values for high and low excitation.

## Related questions

Answer : The armature current of the synchronous motor has large values for low and high excitation.

Description : The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole)  (A) has q -axis current only (B) has d -axis current only (C) has both d and q axis currents (D) cannot be divided between q and d axis currents

Answer : The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole) has d -axis current only

Answer : In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be more than full-load current.

Description : A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is

Answer : A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is 36 Ohm

Description : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?

Answer : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because stator supply is not required to produce magnetic field.

Description : In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as  (1) synchronous motor (2) synchronous generator (3) asynchronous motor (4) asynchronous generator

Answer : In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as synchronous generator

Description : The armature reaction in a synchronous generator supplying leading power factor load is (A) magnetizing (B) demagnetizing (C) demagnetizing and cross-magnetizing (D) magnetizing and cross-magnetizing

Answer : The armature reaction in a synchronous generator supplying leading power factor load is magnetizing and cross-magnetizing

Description : The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as?

Answer : Slip-rings in a synchronous motor carry direct current.

Answer : The efficiency of a properly designed synchronous motor will usually fall in range 85 to 95%.

Answer : A synchronous motor running with normal excitation adjusts to load increases essentially by increase in armature current.

Answer : In case one phase of a three-phase synchronous motor is short-circuited the motor will not start.

Answer :  The size of a synchronous motor decreases with the increase in flux density.

Description : What is the maximum value of torque angle in synchronous motor?

Answer : The maximum value of torque angle in synchronous motor is 90 degrees electrical.

Description : Hunting in synchronous motor cannot be due to?

Answer : Hunting in synchronous motor cannot be due to windage friction.

Description : The damping winding in synchronous motor is generally used to?

Answer : The damping winding in synchronous motor is generally used to provide starting torque and prevent hunting.

Description : In a synchronous motor which losses varies with load?

Answer : In a synchronous motor, copper losses varies with load.

Answer : The operating speed of a synchronous motor can be changed to new fixed value by changing frequency.

Answer : A synchronous motor can develop synchronous torque at synchronous speed.

Answer : The duration of sudden short-circuit test on a synchronous motor is usually about one second.

Description : The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as?

Answer : The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as pull-in torque.

Answer : The construction of a synchronous motor resembles an alternator.

Answer : If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop.

Answer : The coupling angle or load angle of synchronous motor is defined as the angle between the rotor and the stator poles of opposite polarity.

Answer : If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then the stator current will be zero.

Description : Which motor have more efficiency, synchronous motor or induction motor?

Answer : Synchronous motor has more efficiency.

Description : If we change the excitation of synchronous machine will it affect on motor speed?

Answer : No, If we change the excitation of synchronous machine it will not affect on motor speed.

Description : How can we reverse the direction of rotation of synchronous motor?

Answer : By reversing supply phase sequence we can reverse the direction of rotation of synchronous motor.

Description : If the load of the normally excited synchronous motor is increased the power factor will?

Answer : If the load of the normally excited synchronous motor is increased the power factor will become lagging.

Description : The synchronous motor which works on leading power factor and does not drive any mechanical load is called?

Answer : The synchronous motor which works on leading power factor and does not drive any mechanical load is called synchronous condenser.

Description : If the field of synchronous motor is under excited, power factor will be?

Answer : If the field of synchronous motor is under excited, power factor will be lagging.

Description : An unexcited single phase synchronous motor is ?

Answer : An unexcited single-phase synchronous motor is reluctance motor.

Description : A synchronous motor can be made self starting by providing?

Answer : A synchronous motor can be made self-starting by providing damper bar.

Description : The back emf of synchronous motor depends on?

Answer : The back emf of synchronous motor depends on load angle.

Description : Synchronous motor always runs at which speed?

Answer : Synchronous motor always runs at synchronous speed.

Description : Can we use the synchronous motor as the synchronous capacitor?

Answer : Yes, we can use the synchronous motor as the synchronous capacitor when the synchrnous motor is overexcited.

Description : The synchronous motor will develop maximum power when the load angle is?

Answer : The synchronous motor will develop maximum power when the load angle is 900.

Description : what will happen when excitation of an unloaded salient pole synchronous motor suddenly gets disconnected?

Answer : When excitation of an unloaded salient pole synchronous motor suddenly gets disconnected the motor will stop.

Description : Three phase synchronous motor will have how many sliprings?

Answer : Three phase synchronous motor will have two sliprings.

Answer : In a A.C. series motor armature coils are usually connected to commutator through resistance.

Description : The normal value of the armature resistance of a d.c. motor is?

Answer : The normal value of the armature resistance of a d.c. motor is 0.5.

Answer : When the armature of a D.C. motor rotates, e.m.f. induced is back e.m.f.

Answer : The armature voltage control of D.C. motor provides constant torque drive.

Answer : The armature torque of the D.C. shunt motor is proportional to armature current.

Description : Armature control of DC motor

Answer : Armature control of DC motor

Description : Draw and explain V and inverted V curves for synchronous motor.

Answer : V curves' and inverted V curves' for Synchronous Motor:  V curve:  V curve is a plot of the stator current versus field current for different constant loads. The graph is plotted ... Vcurves of synchronous motor. The highest point on each of these curves indicates unity power factor.

Description : List different torques in synchronous motor.

Answer : Different Torques in Synchronous Motor: 1) Starting torque 2) Running torque 3) Pull-in torque 4) Pull-out torque

Description : Damper winding in a synchronous motor

Answer : Damper winding in a synchronous motor Serves to start the motor.

Description : In a self-controlled synchronous motor fed from a variable frequency inverter  (1) the rotor poles invariably have damper windings  (2) there are stability problems  (3) the speed of the rotor decides stator frequency  (4) the frequency of the stator decides the rotor speed

Answer : In a self-controlled synchronous motor fed from a variable frequency inverter the frequency of the stator decides the rotor speed

Answer : In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will run as induction motor.

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