Other split-phase motor characteristics: Maximum running torques range ...
In this sense, the auxiliary coil in this design can be regarded as a starting coil, since it is only used during motor startup.Another way to further improve on the single-coil single-phase induction motor design is to introduce an auxiliary coil, which remains powered not only during the motor startup phase, but also during normal operation.These motors are not practical due to their inability to reliably start rotation on their own.One way to improve on the single coil design is by using an auxiliary coil in series with a motor starting capacitor.Motors with a single coil have to be started by using an external force, and can rotate in either direction.
The direction of the rotation depends on the external force.
The rotating magnetic field is easily achieved in three-phase asynchronous motors because the phase angle offset between the individual phases is 120 degrees.
However, single-phase AC motors require external circuitry which creates the phase angle offset in order to produce a rotating magnetic field.
They come in various voltage ratings, depending on the application they were intended for.
Some single phase AC motor designs use motor run capacitors, which are left connected to the auxiliary coil even after the start capacitor is disconnected by the centrifugal switch.
As opposed to an AC motor using only a motor start capacitor, which creates a pulsating magnetic field during normal operation, AC motors using a motor start capacitor and a motor run capacitor create a rotating magnetic field during normal operation.