How to troubleshoot excessive vibration or abnormal noise in AC Centrifugal Fans?

1. Check Foundation Installation and Mechanical Components

Excessive vibration and abnormal noise often stem from loose or damaged mechanical structures, which is the first step in troubleshooting.

Check coupling and concentricity: The centrifugal fan and motor are connected by a coupling. If the coupling has poor concentricity, excessive clearance, or is damaged, it will cause impact forces during transmission, resulting in severe vibration and noise.

Tighten anchor bolts and check levelness: When the fan body is installed on the base, the anchor bolts must be tightened and the base must be level. Loose bolts or tilted installation will cause fan vibration and amplify noise through structural transmission.

Bearing lubrication and wear inspection: Bearings are the core rotating components of the fan. Insufficient lubrication, deteriorated lubricating oil, or severe bearing wear will lead to unstable operation and generate mechanical friction noise. Regularly changing the lubricating oil and checking the bearing condition is crucial.

2. Check Electrical Parameters and Load Balancing

In addition to mechanical components, electrical system mismatches can also lead to abnormalities.

Rotor balance and motor shaft alignment: If the motor rotor or fan impeller is unbalanced, or the motor shaft and fan shaft are not precisely aligned (shaft alignment), centrifugal force imbalance will occur during high-speed operation, leading to strong centrifugal vibration and noise.

Check motor current and power factor: During operation, use an instrument to measure the motor current. If the current is abnormally high, it may be caused by excessive fan load (such as excessively high pipe resistance) or internal motor failure. Load imbalance can also cause the motor to vibrate. Inspect the pulleys and drive system: If the fan is driven by a belt (in some models), wear on the pulleys, insufficient tension, or belt slippage can also cause noise and vibration.

3. System Resistance and Environmental Factors Inspection

The overall system resistance matching and environmental installation also affect the operating state.

Check inlet and outlet resistance: If incorrect filters, silencers, or fire dampers are installed at the fan's inlet and outlet, leading to abnormally increased resistance, the fan load increases, which may generate abnormal noise and vibration.

Inspect mounting brackets and vibration damping devices: Centrifugal fans are usually equipped with spring brackets or vibration dampers. If the vibration damping device ages and fails, the vibration will be transmitted through the brackets to the machine room structure, amplifying the noise. The elasticity of the vibration dampers needs to be checked.

Environmental resonance check: Sometimes the low-frequency vibration generated by the fan can resonate with the machine room structure, amplifying the noise. In this case, it may be necessary to add structural support or change the fan installation location.