Recently a 300 hp 3600rpm sleeve bearing motor was put into service at our facility.
Initial vibration spectrums show a 2xline(7200)vibration at the inboard horizontal position of .23 in/sec 0-pk velocity. This is the only point on the motor that shows elevated 2xline vibrations.Data was taken with high resolution to seperate running speed from 2xline.
If there is an electrical problem would it only present itself at one location, or would it appear at other locations on the motor?
Thanks in advance,
Robbie

Usually shows in more than one position, unless there is a possible "bad" softfoot at that position causing a distortion in the motor housing and a very uneven airgap.

3600 rpm motors are notorious for 2x LF, but I would check for softfoot. Some recommend loosening one bolt at a time to find the cause of the distortion, but do not do it on my say so. Be your on judge there.

It certainly could be an airgap problem. If you moved the rotor off-center in horizontal direction on one end only, then you might get 2*LF vibration only in H direction on that end. On a horizontal sleeve bearing motor, there may be relatively easy access to remove endplates and check the airgap in place.

I agree with Ralph, the best bet is to check for soft foot condition first. It should not be a problem to loosen one foot at a time and monitor vibration imo (are you expressing reservations about that procedure Ralph?).

Thanks,
I probably jumped too quickly because I have had luck in the past with soft foot myself.
I will report back with my findings shortly.
Thanks for the reminder, thats what is great about this board!

Robbie,
Unusual to have only one high reading. Humor me and change your Y scale to log. See if maybe you aren't looking at a localized resonance under 7200 cpm at the point.