Attached is detailed information on the high vibration issue we are experiencing with the PA Fan spare rotor assembly, Model No. PAF 20/11.2-2, a BHEL make (TLT design). BHEL provided a spare rotor assembly for us, but without testing data. When we put the rotor into one of our PA Fans, initial vibration at start-up was 5.0 mm/sec, gradually increasing to 6.5 mm/sec. After 2 years of operation, we removed the rotor assembly for servicing during AOH. We replaced all bearings and rubber seals as per OEM procedure. However, after reinstallation into another PA fan, vibrations remained high at 6.5 mm/sec. We conducted a thorough internal inspection and have kept the rotor assembly in preservation. Drawings and vibration spectrum are available for reference. ---------------------------------- RAKESH SAHOO ----------------------------------
The data presented suggests that the FDE is experiencing excessive looseness, potentially due to issues such as a loose fan base, loose bearing feet, loose bearing cap bolts, loose bearing fit to the shaft, and loose bearing outer race fit to the bearing housing. If the coupling is worn, both the motor and fan may exhibit similar vibration patterns. Additionally, the data indicates possible misalignment or 50Hz electrical noise, with something worn or loose on the FDE. Aligning a machine with worn components could lead to a misalignment peak during operation. RAKESH SAHOO from the original message shared details about high vibration issues faced with a spare rotor assembly for a PA Fan (Model No. PAF 20/11.2-2, BHEL make). The rotor assembly underwent servicing, including replacement of bearings and seals, but vibrations remained higher than normal after installation in another fan. Thorough internal inspections were conducted, and the rotor assembly is currently in preservation. References to drawings and vibration spectra are attached for further analysis. For more information, please visit www.midlandsrc.com.
Before addressing high vibration issues with the PA Fan spare rotor assembly, it is recommended to first check the cleaning of the fan and then proceed with balancing. This is a common procedure for PA fans. If experiencing high vibration with Model No. PAF 20/11.2-2, BHEL make (TLT design), it is important to note that the spare PA fan rotor assembly supplied by BHEL may not have testing data available. After installation and servicing during AOH, vibrations were observed to be higher than the normal operating range. Thorough internal inspections were conducted on the MBA and blade shaft internals, and the rotor assembly is currently in preservation. For more detailed information, attached drawings and vibration spectrum for reference.
Hello Rakesh, I have encountered a similar issue in my previous role related to high vibrations in the PA Fan spare rotor assembly. The vibration spectrum indicates misalignment and looseness, with elevated 2x and run speed harmonics. To address this, I recommend checking the hold down bolts for any looseness, inspecting shims under the motor and fan housing feet for damage, ensuring there is no soft foot, examining the fan blades for any damage, and conducting a detailed inspection including MPT or DPT. Additionally, it is essential to check the alignment, balance the fan to grade G2.5, and inspect the fan bearings for damage patterns. Investigate any changes on the process side, such as load or power adjustments. Detailed information and vibration spectrum are provided for reference. Thank you.
It certainly seems like you've taken extensive measures to rectify the issue with the PA Fan's rotor assembly. Though you've replaced the bearings and seals, have you considered the potential for an imbalance in the rotor? Imbalance could very much contribute to chronic high vibration. It is worth getting the rotor professionally balanced and then conduct another vibration test. It would also be beneficial if you could share the vibration spectrum here, as the pattern could give additional insights about the nature of the issue.
Very intriguing situation, Rakesh. From the data you provided, it seems like the high vibration issue might be related to the rotor balance or alignment rather than the bearings or seals, especially considering you already replaced these components and the problem persisted. Have you tried performing a dynamic balance test or checking the alignment post-installation? That may provide some insight into the cause of this increase in vibration. Another area to check could be possible structural resonances that could've been excited due to the operational speed range. Looking forward to seeing your vibration spectrum and drawings to get a better understanding!
✅ Work Order Management
✅ Asset Tracking
✅ Preventive Maintenance
✅ Inspection Report
We have received your information. We will share Schedule Demo details on your Mail Id.
Answer: Answer: The issue is high vibrations being experienced with the spare rotor assembly, reaching 6.5 mm/sec during operation.
Answer: Answer: During the AOH, all bearings and rubber seals were replaced as per the OEM procedure. However, despite these actions, the vibrations remained high.
Answer: Answer: No, testing data was not provided with the spare rotor assembly by BHEL.
Answer: Answer: The initial vibration at start-up was 5.0 mm/sec, which gradually increased to 6.5 mm/sec during operation.
Answer: Answer: Yes, a thorough internal inspection was conducted, and the rotor assembly was kept in preservation after identifying the high vibration issue.
Join hundreds of satisfied customers who have transformed their maintenance processes.
Sign up today and start optimizing your workflow.