Polymer Plant Blower Bearing Looseness
A blower supplying nitrogen for polymer drying exhibited noise and vibration. After troubleshooting, the issue was traced to a rotor bar problem, resolved through shaft surface welding and bearing housing repairs.
Summary of Mechanical Events
The blower that supply N2 for polymer drying noise and vibration appeared. Blower switch to spare equipment and carry out overhaul work.
By looking at 1X frequency, mechanical fault was suspected, but electric analysis carry-out before motor overhauling due to 2FL frequency.
Trouble Shooting
Due to occurred 1X & 2FL, testing related to check stator or unbalance trouble at first. According to below spectrum Stator didn’t has trouble such as looseness or short. And also, this motor has stand by with 100% same spec. blower. The result of checked V/I spectrums between them, Couldn’t not find out anything.
Finally, testing to check rotor bar trouble in the slightest sense. knew it, Sideband frequency (frb) of rotor bar didn’t occur at this motor.
The Solutions
After overhaul performed (Shaft surface welding repair / mounting bushing in the bearing housing ) 1X and 2FL dramatically decreased.
Lessons Learned
- We learned twice line frequency is symptom of electrical trouble. But it can be caused by other mechanical causes. it is necessary to cross-check by the vibration spectrum and current spectrum for accurate diagnosis.
- Analyzing the spare equipment current can be good example for comparison. If there is no-standby equipment, recording the current spectrum is good solution just in case.
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