Slip

 Slip

When a rotor rapidly accelerates in the direction of rotating field. 

In practice, the rotor can never reach the speed of stator flux. 

If it did, there would be no relative speed between the stator field and rotor conductors.

No induced rotor currents and, therefore, no torque to drive the rotor. 

The friction and windage would immediately cause the rotor to slow down. 

Hence, the rotor speed (N) is always less than the suitor field speed (Ns). 

This difference in speed depends upon load on the motor. 

The difference between the synchronous speed Ns of the rotating stator field and the actual rotor speed N is called slip. 

It is usually expressed as a percentage of synchronous speed Leape slip, s

100(The quantity N-N is sometimes called slip speed. 

(a) When the rotor is stationary (ie.. N-0), ship, s-1 or 100% 

(b) In any induction motor, the change in slip from no-load to full-load is
handly 0.1% to 3% so that it is essentially a constant-speed motor