AC motors consist primarily of stationary set of windings and rotating magnetic assembly. If the rotating magnet can keep up with the frequency of the alternating current energizing the windings, it will continue to be pulled by pulled around.
--- Single Phase AC Motors ---
They inherently have no definite direction of rotation. Same starting setup can result in the rotation of the rotating magnet in either clockwise or counterclockwise direction. So how to get these type of motors started in a specific direction?
with some help.
--- Single Phase AC Motors (with help) ---
An additional set of windings is positioned differently from the main set and energized with an AC voltage that is out of phase with the AC voltage powering the main set of windings. This phase shift is achieved using a capacitor in series with the supplementary set.
--- Three Phase AC Motors ---
Their AC supply voltage waveforms already have a definite phase sequence, so do the respective magnetic field generated by the windings. These combination of all three phase winding sets working together creates what is called a 'rotating magnetic field'.
