The induction motor has almost constant speed. Low-power induction motors are generally single-phase, short-rotor motors and starters require special devices since they do not have their own starters. The auxiliary coil induction motor as the name already says uses an auxiliary coil, which gives that “boost” at the beginning. There are two coils in the stator, one being of thicker wire with a large number of turns, the central coil and another one of wire with less thickness and with few turns, used only in the starting.
This engine rotates because of the difference between the magnetisms created in the coils. While the auxiliary coil is acting, the magnetism arising from the dissimilarity between the two coils is shifting position and causes the rotor to rotate. After starting, a circuit breaker located on the motor cuts off the auxiliary coil current and the motor continues to operate normally only with the magnetism of the main coil. Ring induction motors have maximum power in the 300 watt range, and are used to drive light loads. The auxiliary coils present up to 600 watts. And, on order, you can get even higher power engines.