1) Difference between slip ring motor and synchronous motor .?

As far as motors go the synchronous motor rotates at the same speed as the rotating magnetic field. They have zero starting torque and require another motor to get them started. They are commonly used in large factories and manufacturing establishments. They have zero % slip, thus they are in "sync" with the rotating magnetic field. They are made with many poles or windings.

A slip ring motor is the other type of motor. The "slip" refers to the lag between the rotating magnetic field in the stator vs the field generated in the rotor. The rotor lags behind the stators field any where between 2-25% with 25% being considered the stalling point for most motors. This is also when the current is the highest, also called the locked rotor current.

"Badbender001" is OK to the point where he describes a "slip ring" motor.

Synchronous motors are also found in mechanical timers, mains electric clocks, etc. Any timing arrangement that uses mains frequency for its rotational speed.

These will also self- start, as the load is light. There is usually a mechanical arrangement to prevent them starting in reverse.

Now, slip ring motors are motors that have a wound rotor, unlike standard induction motors. The windings terminate on metal rings attached to the motor shaft, and carbon brushes bear on the rings for electrical connection. The metal rings are the slip rings. You will find them in very large motors that have heavy starting loads, not so much these days as the motors for lifts.

The voltage applied to the rotor can be controlled to allow the motor to speed up slowly, once it has finally reached speed, the slip rings are shorted, and it runs as a standard induction motor.

In lifts, apart from starting under load, this can be used for speed control.

A synchronous motor operates with a winding in its rotor that's hooked as much as an exterior resistor for velocity administration throughout the time of start up-up, collectively as an induction motor, squirrel caged form has no exterior resistor. The rotor windings are brief-circuited on the ends and is nearly a squirrel. the linked fee of a synchronous motor has no slippage. 2,poles-3600 rpm; 4-poles-1800 rpm; 6poles-1200 rpm collectively as an induction motor has a slip velocity, 2poles- 3540 rpm; 4 poles-1750 rpm; 6poles-1150 rpm.A synchronous motor continually operates with carbon brushes, collectively as induction automobiles would have none.Synchronous automobiles are frequently rated a minimum of 100Hp, collectively as, induction automobiles could be rated in fractional Hp.

Synchronous motors ARE slip ring motors, using DC.

See http://www.engineersedge.com/motors/synchronous_mo...

By the way, you're asking in "Cars and Transportation" category.