what is meant by synchronous induction motor ? and it is related to studies in electrical engineering?

Answer 1

There are synchronous machines and induction machines. Induction machines come in two types; squirrel cage and wound rotor.

SYNCHRONOUS:
Alternating current is fed into a stationary winding located in the outer steel statioanry portion of the machine. The AC waveform generates a magnetic field that varies with time, appearing to move in either a clockwise or anticlockwise direction (depending on the winding arrangement). Direct current is fed to the windings on the rotor - these windings are wound around discrete poles to obtain 'permanent' polarity magnets. The rotor magnets will follow the magnetic field in the stator at exactly synchronous speed. Synchronous speed is defined as (120 x Frequency / Poles).

Note: In some cases, permanent magents are used instead of electromagnets to generate the rotor field. The resulting operation is the same.

INDUCTION (Squirrel Cage):
Stator works the same as a Synchronous machine, using AC current through a winding to generate a magnetic field. The rotor is comprised of bars shorted together at the ends (hence the term squirrel cage). Current in the rotor is induced by the magnetic field of the stator; this means the rotor is always trying to play 'catch up'. It never quite obtains synchronous speed ... the difference is known as 'slip', meaning it runs slightly less than synchronous speed.

INDUCTION (Wound Rotor):
The stator is powered the same as a synchronous machine, with the same magnetic field generation. The rotor is wound similarly to the stator, and has an AC current applied to it as well. Since the rotor magentic field is dependent on the applied current (which is itself independent of the stator current and field), it can be adjusted to provide 'synchronous' operation. This is sometimes called a "synchronous induction" machine.

Answer 2

See the good details in the Can Texan reply.
In summary, an AC synchronous motor will run at a fixed speed regardless of the load (within the limits of the design). The speed is proportional to the frequency of the power supply.
The speed of an AC induction motor will be synchronous at no load and will reduce a few percent as load is applied (within the limits of the design). In some designs the speed will reduce a lot.

Answer 3

AC Power is fed to the stator of the synchronous motor. The rotor is fed by DC from a separate source. The rotor magnetic field locks onto stator rotating magentic field and rotates at the same speed. The speed of the rotor is the function of the supply frequency and the number of magentic poles in the stator. While induction motor rotates with slip i.e RPM is less than the synchronous speed( synchronous speed ( RPM)= 120XFrequency/ No of Poles for which the motor is wound.), the synchronous motor rotates with no slip i.e the RPM is same as the synchronous speed governed by supply frequency and number of poles. The slip energy is provided by D.C excitation power.

Answer 4

A synchronous induction motor is a motor that runs at a synchronous speed. In this motor, supply is fed to the stator winding(which is the armature winding in this case). this develops a rotating field in the air gap. The magnetic field developed by the stator winding interacts with the dc field produced and makes the machine run at sychronous speed. It is definitely related to studies in electrical engineering. In fact, not only electrical enginnering but other branches of engineering too. I , myself, am a mechanical engineering student and we have been taught all this..!!

Answer 5

It runs synchronous to the frequency of the applied power.
With 60Hz power it might run at 1,800rpm.

Answer 6

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