A centrifugal fan is a complex piece of equipment primarily composed of an air inlet, air damper, impeller, motor, and air outlet. Its performance varies depending on operating conditions; consequently, inconsistent operation of its various components can affect overall performance. Optimizing the fan's performance involves addressing several aspects.
Centrifugal fans can be started using either full-voltage or reduced-voltage methods. However, note that full-voltage starting draws a current approximately 5 to 7 times the rated current, whereas starting torque is proportional to the square of the voltage; therefore, reduced-voltage starting should be used if the power grid capacity is insufficient.
During the test run, carefully read the product manual and verify that the wiring matches the wiring diagram. Thoroughly check that the power supply voltage meets requirements, ensure there are no missing phases or incorrect phase sequences, and confirm that the capacities of the electrical components are adequate.
At least two people should conduct the test run: one to control the power supply and the other to monitor the fan's operation, shutting it down immediately for inspection if any abnormalities arise. First, verify the correct direction of rotation. Once the fan starts, immediately check for balanced phase currents and ensure the current does not exceed the rated value; shut down and inspect if any irregularities occur. After five minutes of operation, stop the fan to check for abnormalities before restarting.
When testing a dual-speed centrifugal fan, start at low speed first to verify the correct rotation direction. When switching to high speed, the fan must come to a complete stop before starting to prevent reverse rotation at high speed, which could trip the circuit breaker or damage the motor.
Once the fan reaches normal operating speed, measure the input current to ensure it is within the normal range; the operating current must not exceed the rated current. If the operating current exceeds the rated value, check the power supply voltage.
The required motor power depends on operating conditions; for centrifugal fans and fan housings, the power demand is highest when the air inlet is fully open. Operating with the air inlet fully open poses a risk of motor damage. During the test run of the fan, it is advisable to close the valve on the inlet or outlet duct; once the fan is running, gradually open the valve until the required operating conditions are reached, while monitoring the operating current to ensure it does not exceed the rated current.
