Synchronous motors are generally not self-starting because

In case one phase of a three-phase synchronous motor is short-circuited the motor will

A pony motor is basically a

A synchronous motor can develop synchronous torque

A synchronous motor can be started by

A three-phase synchronous motor will have

Under which of the following conditions hunting of synchronous motor is likely to occur ?

When the excitation of an unloaded salient pole synchronous motor suddenly gets disconnected

When V is the applied voltage, then the breakdown torque of a synchronous motor varies as

The power developed by a synchronous motor will be maximum when the load angle is

A synchronous motor can be used as a synchronous capacitor when it is

A synchronous motor is running on a load with normal excitation. Now if the load on the motor is increased

The synchronous motor is not inherently self-starting because

As the load is applied to a synchronous motor, the motor takes more armature current because

Synchronous motor always runs at

An over-excited synchronous motor takes

The working of a synchronous motor is similar to

The minimum armature current of the synchronous motor corresponds to operation at

In a synchronous motor, the magnitude of stator back e.m.f. £& depends on

If load (or torque) angle of a 4-pole synchronous motor is 6° electrical, its value in mechanical degrees is

For V-curves for a synchronous motor the graph is drawn between

The back e.m.f. of a synchronous motor depends on

In a synchronous motor which loss varies with load ?

A synchronous motor can be made self starting by providing

The oscillations in a synchronous motor can be damped out by

The shaft of synchronous motor is made of

When the field of a synchronous motor is under-excited, the power factor will be

The speed regulation of a synchronous motor is always

The percentage slip in case of a synchronous motor is

The operating speed of a synchronous motor can be changed to new fixed value by

A synchronous motor will always stop when

riunting in a synchronous motor takes place

When load on an over-excited or under excited synchronous*motor is increased, rate of change of its armature current as compared with that of power factor is

The rotor copper losses, in a synchronous motor, are met by

The maximum power developed in a synchronous motor occurs at a coupling angle of

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

In which of the following motors the stator and rotor magnetic field rotate at the same speed ?

Synchronous motors are

The standard full-load power factor ratings for synchronous motors are

A synchronous motor running with normal excitation adjusts to load increases essentially by increase in

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

A synchronous motor working at leading power factor can be used as

Slip rings are usually made of

An over excited synchronous motor is used for

When the voltage applied to a synchronous motor is increased, which of the following will reduce ?

To limit the operating temperature an electrical machine should have proper

Slip-rings in a synchronous motor carry

The armature current of the synchronous motor has higher values for

In a synchronous motor running with fixed excitation, when the load is increased three times, its torque angle becomes approximately

The angle between the rotating stator flux and rotor poles is called _____ angle.

Which of the following methods is used to start a synchronous motor ?

When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop

An important advantage of a synchronous motor over wound round induction motor is that

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

Power factor of a synchronous motor is unity when

Change of D.C. excitation of a synchronous motor changes

While starting a synchronous motor by induction motor action, field winding is usually

Which of the following motors will be used in electric clocks ?

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

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

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

Armature of a synchronous machine is

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

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

Stability of a synchronous machine

The power factor of a synchronous motor is better than that of induction motor because

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

A synchronous motor is running with normal excitation. When the load is increased, the armature current drawn by it increases because

If one-phase of a 3-phase synchronous motor is short-circuited, motor

If the field circuit of an unloaded salientpole synchronous motor gets suddenly open-circuited, then

In which of the following motors the stator and rotor fields rotate simultaneously ?

The speed of a synchronous motor

A rotory converter can also be run as a

The maximum speed variation in a 3-phase synchronous motor is

Which of the following resistances can be measured by conducting insulation resistance test on a synchronous motor ?

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 maximum power developed depends on all of the following except

In a 3-phase synchronous motor, the negative phase sequence exists when the motor is

In a synchronous motor, damper windings are provided on

The net armature voltage of a synchronous motor is equal to the

The ratio of starting torque to running torque in a synchronous motor is

In a synchronous motor, the magnitude of stator back e.m.f. Eb depends on

A 3-phase synchronous motor is running clockwise. If the direction of its field current is reversed

The magnitude of field flux in a 3-phase synchronous motor

The torque angle, in a synchronous motor, is the angle between

Hunting in a synchronous motor cannot be due to

By which of the following methods the constant speed of a synchronous motor can be changed to new fixed value ?

In a synchronous motor, V-curves represent relation between

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

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

. Which of the following motors is non-self starting ?

. 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, the damping winding is generally used to

. If the field of a synchronous motor is underexcited, the power factor will be

. The back e.m.f. in the stator of a synchronous motor depends on

. The maximum value of torque that a synchronous motor can develop without losing its synchronism, is known as

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

. Which of the following losses, in a synchronous motor, does not vary with load?

. The size of a synchronous motor decreases with the increase in

. Which of the following losses is not dissipated by the stator core surface in a synchronous motor ?

. The duration of sudden snort-circuit test on a synchronous motor is usually about

. 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 machine with low value of short-circuit ratio has (6) high stability limit

. The construction of a synchronous motor resembles

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

. For power factor correction, synchronous motors operate at

. 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

. Exciters of synchronous machines are

. The coupling angle or load angle of synchronous motor is defined as the angle between the

. If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then

The armature current of the synchronous motor

. The maximum power developed in a synchronous motor will depend on

. A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as

. A synchronous motor develops maximum power when load angle is

. In a synchronous motor, the breakdown torque is