The electric motor with starting capacitor is similar to the split phase motor, but the main difference is in the inclusion of a capacitor (electrolytic) in series with the auxiliary winding of the motor.
This capacitor allows a large phase difference between the main winding currents and starting winding, which becomes indispensable between the magnetic fields aiding in the starting torque of the single-phase electric motor. The starting capacitor for single-phase motors has the function of creating a starting torque having basically two uses, for permanent use and for instantaneous use.
Due to the high starting torque, the starter capacitor motor is manufactured in capacities ranging from 1/4 hp to 15 hp and can be used in a wide variety of applications such as fans and hoods, washing machines emergency exit signs, centrifugal pumps and hermetic compressors, among others. Three-phase motors do not use capacitors.
As in the split-phase electric motor, the auxiliary circuit is disconnected when the motor reaches approximately 80% of its service speed, and after that time, the auxiliary circuit is disconnected, its operation is similar to that of the split-phase motor.