Description : What is back EMF of synchronous motor?
asked
Mar 15, 2018
by
anonymous
Description : What is the back EMF of a dc motor?
asked
Mar 15, 2018
by
anonymous
Description : What is the back EMF of the motor?
asked
Mar 15, 2018
by
anonymous
Answer :
The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is 0.5.
asked
Mar 20, 2018
by
anonymous
Answer :
The armature may burn if the back e.m.f. of a D.C. motor vanishes suddenly.
asked
Mar 20, 2018
by
anonymous
Description : What is back emf?
Answer :
Back EMF: When a current carrying conductor is placed in a magnetic field it experiences a force; when it moves due to the force it (conductor) cuts the magnetic field due to which an emf is ... (hence the applied armature voltage) is opposed by the induced emf which is therefore called as Back emf.
asked
Apr 27, 2020
by
anonymous
Description : Do AC induction motors have back EMF?
asked
Mar 15, 2018
by
anonymous
Description : What is back EMF in inductor?
asked
Mar 15, 2018
by
anonymous
Description : What is the back EMF in Transformers?
asked
Mar 15, 2018
by
anonymous
Description : What is the back EMF?
Answer :
When the armature of a d.c. motor rotates under the influence of the driving torque, the armature conductors move through the magnetic field and hence e.m.f. is induced in them as in a generator. The ... that energy conversion in a d.c. motor is only possible due to the production of back emf.
asked
Mar 15, 2018
by
anonymous
Answer :
In case of D.C. shunt motors the speed is dependent on back e.m.f. only because flux is practically constant in D:C. shunt motors.
asked
Mar 20, 2018
by
anonymous
Answer :
The duration of sudden short-circuit test on a synchronous motor is usually about one second.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 18, 2018
by
anonymous
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.
asked
Mar 18, 2018
by
anonymous
Answer :
Slip-rings in a synchronous motor carry direct current.
asked
Mar 20, 2018
by
anonymous
Answer :
The efficiency of a properly designed synchronous motor will usually fall in range 85 to 95%.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Answer :
A synchronous motor running with normal excitation adjusts to load increases essentially by increase in armature current.
asked
Mar 20, 2018
by
anonymous
Answer :
The operating speed of a synchronous motor can be changed to new fixed value by changing frequency.
asked
Mar 20, 2018
by
anonymous
Answer :
A synchronous motor can develop synchronous torque at synchronous speed.
asked
Mar 20, 2018
by
anonymous
Answer :
In case one phase of a three-phase synchronous motor is short-circuited the motor will not start.
asked
Mar 20, 2018
by
anonymous
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.
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.
asked
Mar 20, 2018
by
anonymous
Answer :
The construction of a synchronous motor resembles an alternator.
asked
Mar 20, 2018
by
anonymous
Answer :
If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop.
asked
Mar 20, 2018
by
anonymous
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?
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Answer :
The armature current of the synchronous motor has large values for low and high excitation.
asked
Mar 20, 2018
by
anonymous
Description : Which motor have more efficiency, synchronous motor or induction motor?
Answer :
Synchronous motor has more efficiency.
asked
Mar 18, 2018
by
anonymous
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.
asked
Mar 18, 2018
by
anonymous
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.
asked
Mar 18, 2018
by
anonymous
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.
asked
Mar 18, 2018
by
anonymous
Description : Hunting in synchronous motor cannot be due to?
Answer :
Hunting in synchronous motor cannot be due to windage friction.
asked
Mar 18, 2018
by
anonymous
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.
asked
Mar 18, 2018
by
anonymous
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.
asked
Mar 18, 2018
by
anonymous
Description : An unexcited single phase synchronous motor is ?
Answer :
An unexcited single-phase synchronous motor is reluctance motor.
asked
Mar 18, 2018
by
anonymous
Description : A synchronous motor can be made self starting by providing?
Answer :
A synchronous motor can be made self-starting by providing damper bar.
asked
Mar 18, 2018
by
anonymous
Description : In a synchronous motor which losses varies with load?
Answer :
In a synchronous motor, copper losses varies with load.
asked
Mar 18, 2018
by
anonymous
Description : Synchronous motor always runs at which speed?
Answer :
Synchronous motor always runs at synchronous speed.
asked
Mar 18, 2018
by
anonymous
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.
asked
Mar 18, 2018
by
anonymous
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.
asked
Mar 18, 2018
by
anonymous
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.
asked
Mar 18, 2018
by
anonymous
Description : Three phase synchronous motor will have how many sliprings?
Answer :
Three phase synchronous motor will have two sliprings.
asked
Mar 18, 2018
by
anonymous
Description : The effect of increasing load on a synchronous motor running with normal excitation is (A) Increase both its Ia and power factor. (B) Decrease Ia, but increase power factor. (C) Increase Ia, but decrease power factor (D) Decrease both Ia and power factor.
Answer :
The effect of increasing load on a synchronous motor running with normal excitation is Increase Ia, but decrease power factor
asked
Apr 28, 2018
by
anonymous
Answer :
An over excited synchronous motor on noload is known as synchronous condenser.
asked
Mar 20, 2018
by
anonymous
Description : List different starting methods of three phase synchronous motor. Explain any one of them.
Answer :
Different Starting Methods of Three Phase Synchronous Motor: As synchronous motor is not self starting, different methods of starting are as follows: 1) By using an Induction (Pony) motor 2) ... . The rotor gets pulled into synchronism and starts running at constant speed as a synchronous motor.
asked
May 7, 2020
by
anonymous
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.
asked
May 7, 2020
by
anonymous
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
asked
May 7, 2020
by
anonymous