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DINGFENG CAPACITOR - - Working principle of single-phase single-capacitor and double-capacitor AC asynchronous motors

Issue Time:2020-04-20

The single-phase capacitor AC motor is often used in industrial water pumps, oil pumps, fans, low-power mechanical equipment, etc. due to its small size and light weight. And in civil appliances, such as refrigerators, air conditioners, washing machines, are also widely used.

 

<1>. Operation mode

 

1. The secondary winding of a single-capacitor start-up asynchronous motor is connected in series with a larger-capacity start-up capacitor (C) and centrifugal switch (K) to the main winding and connected to the power supply. When the speed of the motor reaches 75% ~ 80% of the synchronous speed (1500, 3000), the centrifugal switch cuts off the secondary winding and the starting capacitor stops working.

 

2. The secondary winding of the single-capacitor asynchronous motor is connected in series with a running capacitor whose capacity is much smaller than the starting capacitor of the single-capacitor asynchronous motor, and then connected to the power supply in parallel with the main winding. And the auxiliary winding and running capacitor always participate in the operation of the motor.

 

3. The stator winding structure of the double-capacitor asynchronous motor is the same as that of the single-capacitor asynchronous motor. The difference is that the secondary winding is connected in series with two parallel capacitors (the running capacitor and the starting capacitor are connected in parallel via a centrifugal switch), and the main winding is connected to the power supply in parallel. When the motor speed reaches 75% ~ 80% of the synchronous speed (1500, 3000), the centrifugal switch cuts off the starting capacitor. The secondary winding and running capacitor always participate in the operation of the motor.

 

<2>. Starting torque

 

1. The single-capacitor starting asynchronous motor has a higher starting torque, which is generally about 2.8 times the rated torque.

 

2. The starting torque of the single capacitor running asynchronous motor is low, generally about 0.5 times the rated torque.

 

3. The dual-capacitor asynchronous motor has higher starting torque and overload capacity. It is generally about 2.5 times the rated torque.

 

3. Power factor

 

1. The power factor of single capacitor starting asynchronous motor is low, generally 0.6 ~ 0.82.

 

2. The power factor of the single capacitor running asynchronous motor is high, generally 0.8 ~ 0.95.

 

3. The power factor of the dual-capacitor asynchronous motor is high, generally 0.82 ~ 0.9.

 

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