The sliding or sliding basically consists of the difference between the speed of the rotating field and the speed of the rotor. Slip has a direct influence on the frequency of induced electromotive force on the rotor bar. At the moment of starting the electric motor, that is, at the instant the rotor is stopped, the slip is maximum, so S is equal to and the frequency is equal to the supply voltage.
It should be noted that the rotor frequency varies according to the cutting speed of the rotating field force lines, and considering the fact that the sliding is directly proportional to this speed, it can be concluded that the rotor frequency is directly proportional To slipping.
Thus, the value of the induced voltages in the rotor in the case of a coiled rotor depends exclusively on the ratio of coils between the rotor and the stator, so that the stator can be considered as the primary of a transformer and the rotor as its secondary.
This type of machine, when activated by a turbine and operating with a higher rotation than the synchronous one, can produce active power and thus deliver it to the system where it is connected, thus, starting to act as a generator.