Is the starting capacitance of single-phase motor the same as the running capacitance?

2022-10-28 08:54

The starting capacitor enables the starting coil of single-phase motor to be energized during startup and cut off after startup,

The running capacitance is used to compensate the capacitance of the motor during operation, so the starting capacitance can not be less, and the running capacitance can not be used.

No matter what kind of capacitor, it has starting effect at the beginning of single-phase motor starting. 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 starting process of single-phase motor is actually a process of "phase arrangement". 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 function of the capacitor is to make the starting winding current of the motor be 90 electrician's angles ahead of the running winding in time and space, forming a phase difference. Among them, the operating capacitor also plays a role in balancing the current between the main and secondary windings. Because the starting capacitor works for a short time, the withstand voltage is required to be above 250V, while the operating capacitor works for a long time, and the withstand voltage is required to be above 400V.

For general motors, its capacitance is adjustable speed, generally only a few UF. For asynchronous motors, the capacitance is operating, mostly below 20UF. Of course, there are also large ones, which mainly depends on the motor power. Some motors "smoke" during operation. It is estimated that the current of the motor is too high, and the winding is overheated, resulting in short circuit burning. Most of them are not capacitor problems. The short circuit breakdown of capacitor rarely sees smoke, but sometimes can smell a special odor.