Electric motors are responsible for much of the energy consumption in industries. In the industrial sector between 50 and 60% of the electric energy used is consumed by electric motors, hence the importance and necessity of using ever more efficient motors. An electric motor can be defined as a device that transforms electrical energy into another form of energy or that transforms electrical energy with certain characteristics into another form of energy with other characteristics.
When an electric current passes through a conductor, a magnetic field is created around it. If we place this conductor in a region of fixed magnetic field, the conductor will be subjected to an electromagnetic force that will have the effect of displacing the conductor. Thus, the principle of operation of an elementary electric motor arises. All electric motors are composed of a coil where the magnetic field is created and this event appears in the fixed part of the motor that when subjected to a magnetic field created by the electric current receives the name of inductor. The same event arises in the moving part which is where induced electromotive forces will arise, being called induced.
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.