"Cydrome Leader" wrote: Explain this slip speed for us.
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I'll be happy to try. The motor has a set of stationary windings which
produce a rotating magnetic field. Depending on the number of poles. this
field will go around at 3600 or1800 RPM, usually*. The rotor is made of
magnetic laminations and heavy copper windings. If the rotor were to turn
at synchronous speed (3600 or 1800)* there would be no "slip." So no
current would be induced in the rotor windings, and there would be no
torque. So the rotor would slow down. This would cause the rotating
magnetic field to cut the rotor windings, inducing current in the windings.
This induced current creates a magnetic field in the rotor which makes it
develop torque. The more torque the motor is asked to deliver, the more it
slows down, increasing the "slip," and developing the required torque.
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* In the US and other countries that use 60 cycles. In Britain, the
syncronous speeds are 3000 and 1500.

"Slip" is the difference in RPM between the rotating magnetic field and the
rotor.