Why the provision of field winding on the rotor and armature winding on the stator in case of large synchronous machines is generally preferred?

More Efficient: With armature on the Stator and Field winding on the Rotor, only two slip rings are required due to which losses associated with slip ring and carbon brushes are reduced and efficiency increases.

Why field winding is on rotor in synchronous motor?

The induction generator’s rotor is rotated by a prime mover, which turns faster than synchronous speed. As the rotor windings cut through the rotating field, a current is induced in them. This induced current creates a field that, in turn, cuts through the stator windings to create power output to the load.

Why is rotor field winding excited by DC but not AC?

So if we give AC supply the pole created in the rotor winding will be alternating and it not be created any magnetic locking with the stator field. So if we give AC supply, the rotor will stop rotating after removing the prime mover. This was the reason Why DC is used not AC for excitation of Synchronous Motor.

Why is field winding placed on the stator of a DC machine?

The rotating armature of DC machines has alternating current generated in its windings; this is then rectified to DC by the commutator. The necessary field is thus provided on the stator, or stationary portion, of the machine.

What is field winding in DC generator?

field winding in Electrical Engineering A field winding is the insulated current-carrying coils on a field magnet that produce the magnetic field needed to excite a generator or motor. As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding.

Why we give DC excitation to the field of an alternator?

Originally Answered: Why dc is used as excitation of alternator? Its because you need a constant field. If you give ac it produces a time varying field. In a constant field the armature cuts the flux, hence a time varying emf is induced.

What happened if field winding of the synchronous motor is short circuited?

In the case of an induction motor, the field winding is permanently short-circuited by end rings. In a Synchronous motor, the rotor winding is supplied with DC excitation. Therefore if we short circuit the field winding of a synchronous motor then it will behave as an induction motor.

What is DC field excitation of synchronous generator?

The DC output of the main exciter is given to the field winding of the synchronous machine through brushes and slip rings. The pilot exciter is excluded in smaller machines. For medium-size machines, AC Exciters are used in place of DC Exciter. AC Exciters are three-phase AC generators.

Why DC field excitation is used in synchronous machine?

Synchronous motor excitation refers to the DC supply given to rotor which is used to produce the required magnetic flux. CASE 2: If the field current is not sufficient enough to produce the required air gap flux as demanded by V, additional magnetizing current or lagging reactive VA is drawn from the AC source.

Why is the armature of a dc machine placed on the rotor and the field winding on the rotor and not the other way?

The armature winding of a dc machine is placed on the rotor to facilate commutation ie to convert the alternating voltage produced in the winding into direct voltage at the brushes. In a DC machine one part has to rotate with respect to the other.

Why is the field producing winding of a three phase induction motor made stationary?

Making the field winding stationary element eliminates the use of slip rings and brushes and, therefore, will result in a very trouble-free construction. why does the rotor of a 3-phase induction motor rotate in the same direction as the rotating field?

Why the field winding is placed on rotor in 3 phase alternator?

The field winding of an alternator is placed on the rotor and is connected to the DC supply through two slip rings. It is easier to insulate stationary winding for high voltages for which the alternators are usually designed.