Lecture
This lecture demonstrates the measurement of the rotating field in the air gap of an asynchronous motor using a small coil to measure the induced voltage, which is directly proportional to the magnetic field. By connecting the motor to a three-phase system, the instructor shows how the induced voltage varies with the coil position in the air gap, revealing the presence of four poles in the asynchronous motor. Additionally, the effect of the rotating field is illustrated by observing the rotation of a small ball and a brass tube in the air gap, showcasing how the asynchronous motor induces Foucault currents that generate a rotational force, and how changing the phase sequence can alter the direction of rotation.