Precautions for general purpose fans

The grounding of the fan housing or motor housing must be reliable;

It is forbidden to rotate in the opposite direction, to run beyond the rated current, and to run out of phase;

It is forbidden to maintain the fan during operation.

Commissioning of general purpose fans

The fan is allowed to start at full pressure or start with step-down, but it should be noted that the current at full-voltage start is about 5~7 times the rated current, and the step-down starting distance is proportional to the square of the current. (When the power is greater than 11KW, it is advisable to use step-down start.) When the fan is tested, the product manual should be carefully read and whether the wiring method is consistent with the wiring diagram; It should be carefully checked whether the working voltage of the power supply to the fan meets the requirements, whether the power supply is out of phase or in phase, and whether the capacity of the distribution components meets the requirements.

During the commissioning, the number of people is not less than two, one person controls the power supply, and the other person observes the operation of the fan, and immediately stops the machine for inspection if any abnormal phenomenon is found; First, check if the direction of rotation is correct; After the fan starts to run, it should be immediately checked whether the operating current is balanced and whether the current exceeds the rated current; If there is no normal phenomenon, it should be stopped for inspection. After five minutes of operation, stop the fan to check whether there is any abnormal phenomenon, confirm that there is no abnormal phenomenon and then start operation.

When the two-speed fan is tested, the low speed should be started first, and whether the rotation direction is correct; When starting at high speed, it is necessary to wait for the fan to stand still before starting, so as to prevent high-speed reverse rotation, causing the switch to trip and the motor to be damaged.

When the fan reaches the normal speed, the input current of the fan should be detected to be normal, and the operating current of the fan should not exceed its rated current. If the operating current exceeds its rated current, check whether the voltage supplied to the fan is normal.

The motor power required by the fan refers to the large power required when the air inlet is fully open for the centrifugal fan and the fan box under certain working conditions. If the air inlet is fully open, the motor may be damaged. It is best to close the valve on the inlet or outlet pipeline of the fan during the test run of the fan, and gradually open the valve after operation until the required working conditions are reached, and pay attention to whether the operating current of the fan exceeds the rated current.

General fan surge conditions

1. The working point of the fan falls in the unstable area with a hump-shaped Q-H performance curve;

2. The air duct system has a large enough volume, and it forms an elastic aerodynamic system with the fan;

3. When the frequency of the whole cycle coincides with the oscillating frequency of the system's airflow, it will resonate.