In what condition BPFO will have running speed side bands..
Very vague question, here is some free info.....typically if you see running speed sidebands you are in a late stage of bearing failure.
Depends on how many bearing frequency harmonics you see and the acceleration values of the bearing in question
Ya thats true david..but why it will have running speed sidebands..how bpfo is being modulated by running speed..
Ultimately it is having the fixed location..so impact is of constant amplitude..
It could be due to a significant unbalance. The impact should be stronger when the mass center hits into the defect and weaker when is opposite.
Anyway, I suppose the modulation is not as visible as in the case of an inner race defect and the sidebans should be small
Sidebands in a frequency spectrum are present because of modulation and looseness. Please find the below links for your review and answers to sidebands
Agree david its the phenomena of ampltiude modulation here the carrier frequency is BPFO and the modulating frequency is running speed..
In BPFI its quite obvious as defect is going in the load zone as per shaft RPM so running speed sideband will appear around BPFI..
but outer race is stationary so defect should not modulate by running speed..
But In some cases but not specific cases BPFO will have running speed side bands..some of them is listed below but I am not sure why & how it is modulated?
1. There is severe damage in outer race.
3. Ecentric rotor
I am quite agree with ahruiz..but if unbalance is seavere then normal velocity spectrum should have high values..
but its not happening in this case..