DINGFENG CAPACITOR - - What is the difference between starting capacitor and running capacitor?

Jun 15,2020

Running capacitance: it is to form an alternating magnetic field by connecting the alternating current to the secondary winding after phase shifting. And the alternating magnetic field of the main winding forms an approximately circular elliptical rotating magnetic field. So he can be the same capacitor, but its function is different.

Starting capacitor: It is to energize the starting coil of a single motor when starting, and cut off after starting. The running capacitor is to allow the motor to perform capacitance compensation during operation. Therefore, the starting capacitor must be present, while the running capacitor can be absent.


No matter what kind of capacitor, it has a starting effect at the beginning of the motor. However, when the motor reaches about 75[%] of the rated speed, the starting capacitor is automatically disconnected by the centrifugal switch, and the running capacitor continues to work with the motor. The process of starting the motor is actually the process of "column phase". Because single-phase motors are different from three-phase motors, there is no phase difference, and no rotating magnetic field can be generated. The function of the capacitor is to make the starting winding current of the motor lead the running winding by 90 electrical angles in time and space, forming a phase difference. Among them, the running capacitor also plays a role in balancing the current between the main and auxiliary windings. Since the starting capacitor is an instantaneous and short-term operation, the withstand voltage requirement should be above 250V. The running capacitor must work for a long time, and the withstand voltage is above 400V.


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