Stator windings are a preponderant aspect in all types of electric motors, as they are responsible for the creation of the stator magnetic field. When we speak of three-phase motors, the stator magnetic field is acquired by the passage of current in the stator windings. These three-phase windings are formed by three circuits independent of each other, but identical and fed each one by one of the three phases. Each phase has a resolved number of coils that are housed in the stator slots and are interconnected with each other. These coils are out of phase with each other of 120 ° electrical or electric radians.
Each coil, when fed, operates solitarily and acts as a primary coil of a transformer, producing an alternating magnetic field, but with a fixed direction. In turn, the junction of all partial magnetic fluxes gives rise to a rotating magnetic flux of constant intensity, having as many pairs of poles as groups of three coils have the stator, which depends directly on the number of pairs of poles of the stator. For the fastening of the windings in the stator, grooves are usually used, and these are divided into three large groups: Open Slots, Semi-Open Slots and Closed Slots.