Capacitor Start/Capacitor Run Induction Motor

An induction motor is one of type of AC motor that is supplied by means of electromagnetic induction. This motor has some advantages like has high efficiency and can be used for lower full-load currents. However, this motor is expensive because this motor use centrifugal switch and run and start capacitors. The applications that uses this motor is air compressors, high pressure water pumps, wood working machinery, vacuum pumps and other application that need high torque 1 to 1o hp. Here is the typical circuit of capacitor run/start induction motor:


As you can see, this circuit has run capacitor and start capacitor. The start capacitor is connected in series with the auxiliary winding. The start capacitor is used for high starting torque. The run capacitor also connected in series with the auxiliary winding, after the start capacitor is switched out of the circuit. This circuitĀ  allows high overload torque due to the run capacitor. [Schematic diagram source: Microchip Application Note]