The role and difference of starting capacitor and running capacitor
As we all know, single-phase AC motor is not like three-phase motor, it can turn up when given electricity, it needs a starting torque to rotate, and the clockwise and anti-clockwise of this torque determines the motor's steering, there are many ways to start, one of them is capacitor start, it is customarily called starting capacitor, single-phase motor needs it to turn up smoothly.
However, some single-phase motors have not only one capacitor, some motors have two capacitors, why is that? Because some motors are equipped with a starting capacitor and a running capacitor, what's going on?
Running capacitor: It is the alternating current shifted into the secondary winding to form an alternating magnetic field, and with the alternating magnetic field of the main winding to form an approximately circular elliptical rotating field. So he can be the same capacitor, but its function is different.
Either capacitor has a starting effect at the beginning of the motor start. But when the motor reaches about 75 [%] of the rated speed, the starting capacitor is only automatically disconnected by the centrifugal switch, while the running capacitor accompanies the motor to continue working. The process of starting the motor is actually the process of "phase listing". 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 capacitor is to make the motor's starting winding current in time and space, ahead of the running winding 90 electrician angle, forming a phase difference. Among them, the running capacitor also plays the role of balancing the current between the main and secondary windings. The starting capacitor requires a withstand voltage of 250V or more because it works instantaneously for a short time, while the running capacitor requires a withstand voltage of 450V or more because it works for a long time all the time.
The starting capacitor is to energize the starting coil of a single motor when it is started and cut off after it is started,
while the running capacitor is to compensate the capacitance of the motor during operation, so the starting capacitor cannot be missing, while the running capacitor can be unnecessary.
The running capacitor is used when the press is working normally. The starting capacitor is used when the press is started and the running capacitor is used to start the press. After the press is turned up, the start capacitor is disconnected. The run and start capacitors are together, but one of the start capacitors is open, and the start capacitor is useless when the motor is turned on.
After Z, what is the difference between the start capacitor and the run capacitor? The capacity of start capacitor is large,
usually 2-5 times of run capacitor, while the capacity of run capacitor is small, and the difference between the two capacities is huge and easy to distinguish.
What is the main difference between the two?
Different status
Start capacitor: After the motor starts, the start capacitor is disconnected by the separation switch.
Running capacitor: After the motor starts, the running capacitor is involved in running with the starting coil.
Different capacity
Start capacitor: about 200 microfarads.
Running capacitor: about 20-30 microfarads.
Different roles
Starting capacitor: The starting capacitor is to make the starting coil of a single motor energized when starting and cut off
after starting.
Running capacitor: It makes the motor play capacitor compensation in running, starting capacitor can't be less, while running capacitor can be not used.