5.2.2. Asynchronous principle
Due to the torque effect the rotor begins to rotate in the direction of the rotating field. Commensurately the rotor virtually accepts torque nD of the rotating field which it, however, never actually attains.
The magnetic flow change dwindles to the extent that the rotor speed draws closer to the speed of the rotating field. Should the rotor attain the speed of the rotating field, then the magnetic flow change is zero. In that case no rotor voltage is induced. Thus, the motor cannot generate a torque.
U2 = 0 → I2W = 0 → M = 0
The operating condition of the synchronous run cannot be assessed because of the unavoidable idling torque to overcome the friction bearing and air friction, so that the motor must always run in an asynchronous manner.
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