Structural Looseness at a VSD ID Fan
High vibration in the RH direction of a VSD ID Fan was caused by structural looseness due to cracks in the grout base and anchor bolts. Balancing the fan and adding new anchor bolts reduced the vibration to 1.5 mm/s.
VSD ID Fan 90 Kw
speed = 3000 Rpm
In this case we noted
1-high vibration in RH direction reach 16 mm/s
2- 1x peaks in spectrum
3- sinsoudal TWF with impact for every revolution
4- highest value reach bear 80to 90% of full speed .
in this case the symptom was structure lossness according to crack in grout base , and anchor bolt
these defect generate resonance .
first off all we try to reduce 1x value by balancng job the value reduce to 7mm/s
after adding new anchor bolt with stiffness triangle shape ,the overall value reduce to 1.5 mm/s .
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