Hi All,

Can this be anthing else than a bearing that is going to fail soon? The machine is 1500 kW AC-motor running at 1500 rpm. I took that data from N-end and in axial direction.

It looks bearing fault to me, but I'm a little unsure because there is no bearing data available. (The other reason is my limited experience...)

Base frequency 89 Hz is 3.56x the running speed 25 Hz.

Thanks,

This message has been edited. Last edited by: Mikko,

I wouldn't be afraid to make that call, based on the limited amount of information you have.

Personally, I'd rather say that I thought it was bad, and we wrong, that to say I thought it was OK, and be wrong.

Mikko,

I agree, likely, damage will be already visible in the bearing. Is any historical data available? What does demodulated data say?

Stan,
I think human psychology works in a such way that if someone makes a false positive call, people forget about the possibility of a false negative scenario (which is of course worse). All they see is a false call which caused them to suffer unnecessary losses.

David

I took that data last week. I took new data today and that 89 Hz spike was almost twise as high as last week. Last week it was 4.5 mm/s. Today I measured 7.5 mm/s (0.3 ips) at 89 Hz. I wonder what will I find tomorrow...

Unfortunately we have no history data. The factory is just starting to collect vibration data and these are the the very first measurements for that machine.

This is how it was today:

This message has been edited. Last edited by: Mikko,

Mikko,

Couple more suggestions. Take velocity spectrum with much better resolution ( no need for such a high Fmax ) in order to: 1. confirm that there is in fact a 3.56x fundamental frequency peak; 2. to resolve the what it appears to be sidebands around 3.56x.

Also please show acceleration and demodulated TWF.

David

The bearing is on my table now. It is FAG 6330 (BPFO = 3,57x). Outer race has 4 cm long and 2 mm deep defect. Balls and inner race are in good shape.

Nice picture. Thanks for the follow-up.