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The role and difference between starting capacitor and running capacitor

Views: 2     Author: Site Editor     Publish Time: 2023-01-11      Origin: Site

    No matter what kind of capacitor it is, it has a starting effect at the beginning of the motor's starting. 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 "phase out". Because single-phase motors are different from three-phase motors, there is no phase difference and no rotating magnetic field can be generated. The role of the capacitor is to make the starting winding current of the motor 90 electrical angles ahead of the running winding in time and space, forming a phase difference. Among them, the running capacitor also plays a role in balancing the current between the primary and secondary windings. Since the starting capacitor works for a short time, the withstand voltage is required to be above 250V, while the running capacitor needs to work for a long time, and the withstand voltage is required to be above 400V.


    The starting capacitor is to make the starting coil of the single-phase motor energized when it starts, and it is cut off after starting. The running capacitor is to make the motor perform capacitance compensation during operation. Therefore, the starting capacitor cannot be less, and the running capacitor can not be used.


    As we all know, a single-phase AC motor is not like a three-phase motor. It can rotate when it is powered. It needs a starting torque to rotate, and the forward and reverse timing of this torque determines the direction of the motor. There are also many ways to start, among which capacitor start is one, which is customarily called a start capacitor, which is needed for a single-phase motor to rotate smoothly.


    However, some single-phase motors have two capacitors, why is this? Because some motors are equipped with a starting capacitor and a running capacitor, what's the matter?


    Running capacitor: It is to connect the alternating current to the auxiliary winding after shifting the phase to form an alternating magnetic field, and form an approximately circular elliptical rotating magnetic field with the alternating magnetic field of the main winding. So it can be the same capacitor, but the role is different.


    The running capacitor is the starting capacitor used when the compressor is working normally. It is used together with the running capacitor to start the compressor when the compressor starts. After the compressor turns up, the starting capacitor is disconnected. The running and starting capacitors are combined together, but one of the starting capacitors has been turned on, and the starting capacitor is useless when the motor turns.


    What is the difference between a starting capacitor and a running capacitor? The starting capacitor has a large capacity, which is generally 2-5 times that of the running capacitor, while the running capacitor has a small capacity, and the capacity difference between the two is large and easy to distinguish.


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