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When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor?

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When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor increases to two times the original value.

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

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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.

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

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

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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?

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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?

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

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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.

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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.

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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 : 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?

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

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

Answer : Three phase synchronous motor will have two sliprings.

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.

Description : In a split-phase induction motor, the resistance/reactance ratios of windings are such that (A) current in the auxiliary winding leads the current in the main winding (B) current in the ... (C) both windings develop the same starting torque (D) both windings develop high starting current

Answer : In a split-phase induction motor, the resistance/reactance ratios of windings are such that current in the auxiliary winding leads the current in the main winding

Description : A three-phase synchronous motor connected to ac mains is running at full load and unity power factor. lf its shaft load is reduced by half and field current is held constant then its new power factor will be

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Answer : An electric motor in which both stator field and rotor rotates with same speed is called synchronous motor.

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

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

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