Since this type of motor has only one phase of power, this machine does not present a rotating field, as usually happens in three-phase motors, however, they have a pulsating magnetic field, which can prevent them from obtaining starting torque, magnetic fields aligned with the stator field are induced in the rotor. Thus, auxiliary windings are used, which are dimensioned and positioned so as to create a second phase, allowing the formation of the rotating field necessary for starting.
Single-phase motors are called this way, due to their field windings, which are connected directly to a source known as single-phase. Single-phase induction motors are seen as a natural option compared to three-phase induction motors in places where three-phase power is not available, such as in rural areas, workshops, offices and homes, for example. Its use is only indicated for reduced power, on average of one to two kw. Amongst the various types of single-phase electric motors, the cage rotor can be distinguished considering its simplicity, ease of projection, reduced maintenance and robust body.