Performance Equations of Three Phase Induction Motor
When balanced 3-? voltages are applied to the stator winding a rotating magnetic field of constant amplitude is produced in the air gap. The speed of this rotating field is given by .
The rotating flux wave cuts the stationary rotor conductors and therefore emf are induced in the rotor conductors. As the rotor circuit is short circuited these induced emfs give rise to current in the rotor conductors. The interaction of these rotor currents with rotating flux wave produces torque in the rotor of a 3-? induction motor and as a consequence rotor begins to rotate. According to len law the develop torque must oppose the cause by which it is produce i flux cutting action. This is possible only if the developed torque forces the rotor to rotate in the direction of rotating field. Due to this the relative speed between rotating flux and rotor conductors is reduced and therefore the flux cutting action also gets reduced. This relative speed between rotating flux wave and rotor.