I. What is the working principle of centrifugal fans?
Centrifugal fans are based on the principle of converting kinetic energy into potential energy. Decelerate and change the flow direction in the casing to convert kinetic energy into pressure energy.
Its main components are the casing, impeller, shaft, suction port, and exhaust port. The impeller generates centrifugal force when it rotates, throws the air out of the impeller, and collects it in the casing to increase the pressure , discharged from the air outlet. After the air in the impeller is discharged, a negative pressure is formed, and the external air is sucked to supplement the fan. The air in the fan blade rotates together with the impeller, and centrifugal force is generated due to the certain mass of the air. The air flows from the population along the blades to the outlet, and a vacuum is formed at the inlet, and the air enters the fan under the action of atmospheric pressure.
Second, how to debug the centrifugal fan
Centrifugal fan is a complex equipment, mainly including air inlet, air valve, impeller, motor , the composition of the air outlet. In different states, the effects of centrifugal fans are also different. Therefore, when different parts operate under different conditions, the effect of the centrifugal fan will be affected. There are many ways to debug the centrifugal fan to the best condition.
1. Centrifugal fans are allowed to start at full voltage or to reduce voltage, but it should be noted that the current at full voltage starting is about 5-7 times the rated current, and the voltage reduction starting torque is proportional to the square of the voltage. Proportional, when the grid capacity is insufficient, the step-down start should be used.
2. When the centrifugal fan is commissioned, the product manual should be carefully read to check whether the wiring method is consistent with the wiring diagram; In the same phase, whether the capacity of the distributed electrical components meets the requirements.
3. There should be no less than two people during the test run. One person controls the power supply and the other person observes the operation of the fan. If any abnormality is found, the machine should be stopped and checked immediately. First, check whether the rotation direction is correct; Immediately check whether the running current of each phase is balanced and whether the current exceeds the rated current; if there is any abnormal phenomenon, it should be stopped for inspection. After running for five minutes, stop the fan to check whether there is any abnormal phenomenon, and then start the operation after confirming that there is no abnormal phenomenon.
4. During the test run of the two-speed centrifugal fan, start at low speed first to check whether the rotation direction is correct; when starting at high speed, the fan must be stopped before starting to prevent the high-speed reverse rotation, which may cause the switch to trip and Motor is damaged.
5. When the centrifugal fan reaches the normal speed, it should be measured whether the input current of the fan is normal, and the running current of the centrifugal fan should not exceed its rated current. If the operating current exceeds its rated current, check whether the supplied voltage is normal.
6. The motor power required by the centrifugal fan refers to the larger power required for the centrifugal fan and the fan case when the air inlet is fully opened under certain working conditions. There is a risk of damage to the motor if the air inlet is fully opened for operation. It is best to close the valve on the fan inlet or outlet pipe during the fan test, and gradually open the valve after operation until the required working condition is reached, and pay attention to whether the fan’s operating current exceeds the rated current.
Debugging the centrifugal fan strictly in accordance with the above debugging methods can make the efficiency of the centrifugal fan reach more than 98%.
