Single-phase motor auto-coupling main winding step-down speed regulating circuit

As shown in the figure, the voltage reduction characteristic of the autotransformer is used to directly reduce the voltage of the main winding LR to achieve the purpose of voltage reduction and speed regulation of the single-phase motor. TA is an autotransformer, and I, II, and III are gears. Since gear III has the highest voltage reduction of TA, when SA is moved to gear III, the speed is the lowest. LA is the auxiliary winding and LR is the main winding.