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Home > Mall Dynamic > What Are The Roles OF Starting Capacitance And Running Capacitance In The Motor?
Single-phase AC motor is not like the three-phase motor, it can turn up to power, it needs a starting torque to rotate, and the torque of the timing and inverse time to determine the motor's steering, there are many ways to start, which capacitor start is a kind of, the habit is called starting capacitance, single-phase motor needs it to turn up smoothly.However, some single-phase motors not only have one capacitor, some motors have two capacitors, which is why? Because some motors are configured with a starting capacitor and a running capacitor, what is going on?
Running capacitance: It is to phase shift the alternating current into the secondary winding to form an alternating magnetic field, and form an approximately circular elliptic rotating magnetic field with the alternating magnetic field of the main winding. So it can be the same capacitor, but it does something different.
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 capacitance is automatically disconnected by the centrifugal switch, and the running capacitance continues to work with the motor. The process of motor starting is actually the process of "column phase". Because the single-phase motor is different from the three-phase motor, there is no phase difference and no rotating magnetic field can be generated. The role of the capacitor is to make the motor's starting winding current in time and space, ahead of the running winding 90 electrical angles, forming a phase difference. Among them, the operating capacitance also plays a role in balancing the current between the main and secondary windings. Because the starting capacitor is a momentary short-time work, the voltage is required to be above 250V, and the running capacitor is to work for a long time, requiring the voltage to be above 450V.
The starting capacitor is to make the starting coil of a single motor energized at start and cut off after start, and the running capacitor is to make the motor play a capacitor compensation during operation, so the starting capacitor can not be less, and the running capacitor can not be used.
The running capacitor is used when the press is working normally. The starting capacitor is used to start the press together with the running capacitor when the press starts. When the press is turned on, the starting capacitor is disconnected. The running and starting capacitors are together, but the starting capacitor is on, and the starting capacitor is useless when the motor is turned on. After that, what is the difference between starting capacitors and running capacitors? That is, the capacity of the starting capacitor is large, generally 2-5 times that of the running capacitor, and the capacity of the running capacitor is small, and the capacity difference between the two is huge and easy to distinguish.
When the single-phase AC motor is running normally, the centrifugal switch inside the single-phase AC motor will disconnect the starting capacitor, and the remaining operating capacitor will run with the rotation of the motor. In fact, the starting capacitor and the running capacitor have the same role, but the starting capacitor has a larger capacity, can obtain a larger starting current, resulting in a larger starting torque, long time running, do not need to run for a long time, if the capacitor is too large, long time running will make the starting coil heat. Therefore, after starting up, the centrifugal switch inside the single-phase AC motor will be switched to a smaller capacity operating capacitor to maintain a rotating magnetic field and avoid coil heating when starting up. The working capacitor allows the motor to act as a capacitor compensation during operation. Therefore, starting capacitance is necessary, running capacitance is not necessary, and some single-phase AC motors do not run capacitors.
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