The operating speed of a synchronous motor can be changed to new fixed value by
The operating speed of a synchronous motor can be changed to new fixed value by
A 3-phase synchronous motor is running clockwise. If the direction of its field current is reversed
A 3-phase synchronous motor is running clockwise. If the direction of its field current is reversed
In a synchronous motor, the magnitude of stator back e.m.f. £& depends on
In a synchronous motor, the magnitude of stator back e.m.f. £& depends on
The power developed by a synchronous motor will be maximum when the load angle is
The power developed by a synchronous motor will be maximum when the load angle is
The net armature voltage of a synchronous motor is equal to the
The net armature voltage of a synchronous motor is equal to the
A rotory converter can also be run as a
A rotory converter can also be run as a
The minimum armature current of the synchronous motor corresponds to operation at
The minimum armature current of the synchronous motor corresponds to operation at
If the field of a synchronous motor is underexcited, the power factor will be
If the field of a synchronous motor is underexcited, the power factor will be
For V-curves for a synchronous motor the graph is drawn between
For V-curves for a synchronous motor the graph is drawn between
In a synchronous motor running with fixed excitation, when the load is increased three times, its torque angle becomes approximately
In a synchronous motor running with fixed excitation, when the load is increased three times, its torque angle becomes approximately
The mechanical displacement of the rotor with respect to the stator, in polyphase multipolar synchronous motors running at full load, is of the order of
The mechanical displacement of the rotor with respect to the stator, in polyphase multipolar synchronous motors running at full load, is of the order of
In which of the following motors the stator and rotor fields rotate simultaneously ?
In which of the following motors the stator and rotor fields rotate simultaneously ?
While starting a synchronous motor by induction motor action, field winding is usually
While starting a synchronous motor by induction motor action, field winding is usually
In a synchronous motor which loss varies with load ?
In a synchronous motor which loss varies with load ?
Synchronous motor always runs at
Synchronous motor always runs at
In a synchronous motor, damper windings are provided on
In a synchronous motor, damper windings are provided on
The angle between the rotating stator flux and rotor poles is called _____ angle.
The angle between the rotating stator flux and rotor poles is called _____ angle.
In a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole number and load torque all are halved. The motor speed will be
In a 3-phase, 4-pole, 50 Hz synchronous motor, the frequency, pole number and load torque all are halved. The motor speed will be
When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop
When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop
The construction of a synchronous motor resembles
The construction of a synchronous motor resembles
If in a synchronous motor, driving a given mechanical load and drawing current at a leading power factor from constant voltage supply its field excitation is increased, its power factor
If in a synchronous motor, driving a given mechanical load and drawing current at a leading power factor from constant voltage supply its field excitation is increased, its power factor
The maximum power developed in a synchronous motor occurs at a coupling angle of
The maximum power developed in a synchronous motor occurs at a coupling angle of
The back e.m.f. in the stator of a synchronous motor depends on
The back e.m.f. in the stator of a synchronous motor depends on
The speed regulation of a synchronous motor is always
The speed regulation of a synchronous motor is always
The induced e.m.f. in a synchronous motor working on leading power factor will be
The induced e.m.f. in a synchronous motor working on leading power factor will be
The magnitude of field flux in a 3-phase synchronous motor
The magnitude of field flux in a 3-phase synchronous motor
A synchronous motor working at leading power factor can be used as
A synchronous motor working at leading power factor can be used as
If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will
If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will
If one-phase of a 3-phase synchronous motor is short-circuited, motor
If one-phase of a 3-phase synchronous motor is short-circuited, motor
A synchronous motor can be started by
A synchronous motor can be started by
The coupling angle or load angle of synchronous motor is defined as the angle between the
The coupling angle or load angle of synchronous motor is defined as the angle between the
If the field circuit of an unloaded salientpole synchronous motor gets suddenly open-circuited, then
If the field circuit of an unloaded salientpole synchronous motor gets suddenly open-circuited, then
The maximum value of torque that a synchronous motor can develop without losing its synchronism, is known as
The maximum value of torque that a synchronous motor can develop without losing its synchronism, is known as
A three-phase synchronous motor will have
A three-phase synchronous motor will have
The armature current of the synchronous motor
The armature current of the synchronous motor
Change of D.C. excitation of a synchronous motor changes
Change of D.C. excitation of a synchronous motor changes
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
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
A synchronous motor installed at the receiving end substation operates with such an excitation that it takes power at lagging power factor. Now if the applied voltage of the synchronous motor goes down, the power factor of the synchronous motor will
A synchronous motor installed at the receiving end substation operates with such an excitation that it takes power at lagging power factor. Now if the applied voltage of the synchronous motor goes down, the power factor of the synchronous motor will
The effect of increasing the load on a synchronous motor running with normal excitation is to
The effect of increasing the load on a synchronous motor running with normal excitation is to
The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as
The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as
A synchronous motor can operate at
A synchronous motor can operate at
If load (or torque) angle of a 4-pole synchronous motor is 6° electrical, its value in mechanical degrees is
If load (or torque) angle of a 4-pole synchronous motor is 6° electrical, its value in mechanical degrees is
While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerting torque is produced by
While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerting torque is produced by
In a synchronous motor, the damping winding is generally used to
In a synchronous motor, the damping winding is generally used to
The torque angle, in a synchronous motor, is the angle between
The torque angle, in a synchronous motor, is the angle between
Stability of a synchronous machine
Stability of a synchronous machine
Power factor of a synchronous motor is unity when
Power factor of a synchronous motor is unity when
Which of the following losses, in a synchronous motor, does not vary with load?
Which of the following losses, in a synchronous motor, does not vary with load?
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
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
The armature current of the synchronous motor has higher values for
The armature current of the synchronous motor has higher values for
Which of the following motors will be used in electric clocks ?
Which of the following motors will be used in electric clocks ?
The back e.m.f. of a synchronous motor depends on
The back e.m.f. of a synchronous motor depends on
A synchronous motor is running with normal excitation. When the load is increased, the armature current drawn by it increases because
A synchronous motor is running with normal excitation. When the load is increased, the armature current drawn by it increases because
The synchronous motor is not inherently self-starting because
The synchronous motor is not inherently self-starting because
Under which of the following conditions hunting of synchronous motor is likely to occur ?
Under which of the following conditions hunting of synchronous motor is likely to occur ?
Mostly, synchronous motors are of
Mostly, synchronous motors are of
Which of the following motors is non-self starting ?
Which of the following motors is non-self starting ?
A pony motor is basically a
A pony motor is basically a
A synchronous motor is running on a load with normal excitation. Now if the load on the motor is increased
A synchronous motor is running on a load with normal excitation. Now if the load on the motor is increased
An over-excited synchronous motor takes
An over-excited synchronous motor takes
The speed of a synchronous motor
The speed of a synchronous motor
In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then
In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then
Due to which of the following reasons a synchronous motor fails to pull into synchronism after applying D.C. field current?
Due to which of the following reasons a synchronous motor fails to pull into synchronism after applying D.C. field current?
In a synchronous motor, the armature current has large values for
In a synchronous motor, the armature current has large values for
Armature of a synchronous machine is
Armature of a synchronous machine is
Synchronsizingpower of a synchronous machine is
Synchronsizingpower of a synchronous machine is
The shaft of synchronous motor is made of
The shaft of synchronous motor is made of
When the field of a synchronous motor is under-excited, the power factor will be
When the field of a synchronous motor is under-excited, the power factor will be
In a synchronous motor, V-curves represent relation between
In a synchronous motor, V-curves represent relation between
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
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
Which of the following losses is not dissipated by the stator core surface in a synchronous motor ?
Which of the following losses is not dissipated by the stator core surface in a synchronous motor ?
When the voltage applied to a synchronous motor is increased, which of the following will reduce ?
When the voltage applied to a synchronous motor is increased, which of the following will reduce ?
A synchronous motor can develop synchronous torque
A synchronous motor can develop synchronous torque
In which of the following motors the stator and rotor magnetic field rotate at the same speed ?
In which of the following motors the stator and rotor magnetic field rotate at the same speed ?
A synchronous machine with low value of short-circuit ratio has
A synchronous machine with low value of short-circuit ratio has
A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because
A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because
To limit the operating temperature an electrical machine should have proper
To limit the operating temperature an electrical machine should have proper
A synchronous motor can be used as a synchronous capacitor when it is
A synchronous motor can be used as a synchronous capacitor when it is
Synchronous motors are
Synchronous motors are
In a synchronous motor, the magnitude of stator back e.m.f. Eb depends on
In a synchronous motor, the magnitude of stator back e.m.f. Eb depends on
Which of the following methods is used to start a synchronous motor ?
Which of the following methods is used to start a synchronous motor ?
Synchronous motors are generally not self-starting because
Synchronous motors are generally not self-starting because
Which of the following resistances can be measured by conducting insulation resistance test on a synchronous motor ?
Which of the following resistances can be measured by conducting insulation resistance test on a synchronous motor ?
A synchronous motor connected to infinite bus-bars has at constant full load, 100% excitation and unity power factor. On changing the excitation only, the armature current will have
A synchronous motor connected to infinite bus-bars has at constant full load, 100% excitation and unity power factor. On changing the excitation only, the armature current will have
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
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
The standard full-load power factor ratings for synchronous motors are
The standard full-load power factor ratings for synchronous motors are
A synchronous motor will always stop when
A synchronous motor will always stop when
The efficiency of a properly designed synchronous motor will usually fall in range
The efficiency of a properly designed synchronous motor will usually fall in range
In a synchronous motor, the breakdown torque is
In a synchronous motor, the breakdown torque is
The maximum power developed in a synchronous motor will depend on
The maximum power developed in a synchronous motor will depend on
When the excitation of an unloaded salient pole synchronous motor suddenly gets disconnected
When the excitation of an unloaded salient pole synchronous motor suddenly gets disconnected
A synchronous motor develops maximum power when load angle is
A synchronous motor develops maximum power when load angle is
A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as
A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as
A synchronous motor running with normal excitation adjusts to load increases essentially by increase in
A synchronous motor running with normal excitation adjusts to load increases essentially by increase in
If excitation of a synchronous motor running with a constant load is decreased from its normal value, ignoring effects of armature reaction, it leads to
If excitation of a synchronous motor running with a constant load is decreased from its normal value, ignoring effects of armature reaction, it leads to
If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then
If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then
Exciters of synchronous machines are
Exciters of synchronous machines are
The oscillations in a synchronous motor can be damped out by
The oscillations in a synchronous motor can be damped out by
The working of a synchronous motor is similar to
The working of a synchronous motor is similar to
Slip-rings in a synchronous motor carry
Slip-rings in a synchronous motor carry
