Why Motor Run Capacitors Are Essential For Your Motors?

Motor Run Capacitors are also known as asynchronous motors, use a rotating magnetic field to produce torque. Three-stage motors are broadly utilized on the grounds that they are dependable and practical. A rotating magnetic field is easily achieved with a three-phase asynchronous motor because the phase displacement angle between each phase is 120°. However, single-phase AC motors require external circuits to create a phase angle displacement to generate a rotating magnetic field. 

AC Single Phase Induction Motor

Single Coil AC Induction Motor

AC induction motors typically use two or more coils to create a rotating magnetic field that produces torque in the airfoil. Single-coil motors must be started with an external force and can rotate in any direction. The direction of rotation depends on the external force. If Motor Run Capacitors turned clockwise, it will continue to rotate and accelerate clockwise until it reaches the maximum speed specified by the line frequency. Similarly, if the initial rotation is anticlockwise, it continues to rotate anticlockwise.

Starting of the Capacitor AC induction motor

One way to improve the single coil design is to use an additional coil in series with the motor starting capacitor except Motor Run Capacitors. Auxiliary coils, are used to create the initial rotating magnetic field. In order to generate a rotating magnetic field, the current flowing through the main coil must be out of phase with the current flowing through the auxiliary coil. When the rotor reaches a sufficient speed, the centrifugal switch disconnects the auxiliary coil from the circuit, leaving the motor powered by a single coil that produces a pulsating magnetic field.

AC Induction Capacitor Motors

Another way to improve the design of single winding single phase with Motor Run Capacitors to introduce an additional coil. The auxiliary coil remains powered during normal operation as well as during the engine starting phase. When the rotor reaches a certain speed by the centrifugal switch, it disconnects from the circuit. From that point on, the auxiliary coil remains powered by the motor's running capacitor. 

Motor Start Vs Motor Run Capacitors

Motor start capacitors

Motor start capacitors are used during the motor starting phase and are disconnected from the circuit when the rotor reaches a certain speed (usually about 75% of the maximum speed for this type of motor). These capacitors usually have capacitance values ​​greater than 70 degrees Fahrenheit. There are different rated voltages depending on the application. 

Also read: Why Motor Start Capacitors Are Essential For Your Motors?

Motor Run Capacitors

Some designs of single-phase AC motors use the motor's starting capacitor which remains connected to the auxiliary winding even after the starting capacitor has been disconnected by a centrifugal switch. These designs work by creating a rotating magnetic field. Motor Run Capacitors are designed for continuous use and will continue to operate as long as the motor is running. Therefore, electrolytic capacitors are not used and instead low loss polymer capacitors are used. The value of the operating capacitor is usually smaller than the value of the starting capacitor, and is often in the range from 1.5°F to 100°F. 

Uses

A single phase AC induction motor uses a motor starting capacitor and a running capacitor. Both are used where single-phase power is more practical than three phase power, as in household appliances. However, it is not as efficient as an AC three phase induction motor. In fact, single phase AC motors are two to four times less efficient than three phase AC motors, so they are only used for low power motors. 

Typical applications that use start and Motor Run Capacitors include in power tools, washers, dryers, dishwashers, vacuum cleaners, air conditioners and compressors.