It can be stated that the auxiliary winding enables the production of a phase shift, which must produce the necessary torque for the initial rotation, as well as the acceleration. https://www.mrosupply.com/motors/ac-motors/general-purpose-motors/2082339_0054dpsa31a-p_toshiba/ In the event that the motor reaches a predetermined speed, the auxiliary winding is disconnected from the mains by means of a switch which is normally driven by a centrifugal force, which is the centrifugal switch or breaker, or in specific cases, by current relay, or other special devices. Since the auxiliary winding is sized appropriately for startup only, its failure to shut down may cause it to burn.
Thus, the angle of lag that can be obtained between the main winding and the auxiliary winding currents is significantly reduced, and therefore, these motors have a starting torque considered lower or subtly higher than the nominal, which may limit their application to fractional powers and loads requiring the reduced or moderate starting torque, as well as office machines, fans and exhaust fans. The split-phase machines have a main winding and an auxiliary used for starting, both lagging in the ninety-degree electric space.