At standstill condition the value of slip is
The slip at standstill can be calculated as follows:
Slip = (synchronous speed - rotor speed) / synchronous speed Slip = (ns - 0) / ns Slip = 1
This means that the rotor is not able to keep up with the rotating magnetic field, and the slip is at its maximum value of 1.
The high slip value results in a low starting torque, which is why induction motors require some kind of external assistance during startup, such as a starting capacitor or a soft starter.