The single-phase distorted-field electric motor stands out among single-phase induction motors, because of the simplest, most reliable and economical starting method. The distorted field motors have low starting torque (15 to 50% nominal), low efficiency (35%) and low power factor (0.45). One of the most common constructive forms is that of protruding poles, and about 25% to 35% of each pole is captured by a shorted copper loop. The induced current of this loop causes the flow through it to suffer a delay in relation to the flow of the part not bonded by it.
The result of this is similar to a rotating field that moves in the direction of the non-interlaced part to the bonded part of the pole, producing torque which will cause the motor to break and achieve nominal rotation. The direction of rotation will depend on the side that is located on the part of the pole, so the distorted field motor has a single direction of rotation. This direction can be reversed by changing the position of the rotor shaft tip relative to the stator. https://www.mrosupply.com/motors/ac-motors/general-purpose-motors/26645_vm3538_baldor/