Dear All;

Attached *. doc is a case history of a 3 Hi Rolling mill Motor in a steel Plant.

Kindly verify the following
Bearing Inaccuracies in the Motor.
Possiblity of Electric Current passage thro' the bearings
Any kind of loose fit/ Too tight fit in the motor.
( The spectrums are taken with 1600 lines resolution and Fmax = 1000HZ) is it recommended for motor at 742 RPM.

fis_TEMP.doc (121 Kb, 33 downloads) 3 Hi Mill Motor

That actually does not look like fluting to me. Fluting usually occurs in the motors I have had it occur in around 2000 HZ with a haystack with sidebands of BPFO. Not yet have I had a Primary with harmonics and sidebands and it be fluting. Without being able to work the curser to see the actual primary and harmonics, my best guess is that you have a BPFO. Damage could have occured during instillation.I assume this was not there right after start up and showed up later.

Mike

Prabhu,

There is definitely some damage in the outer race whether it is fluting or pitting. The g's in the TWF are too high. Audible noise probably supports fluting diagnosis. ( Is this motor on VFD?).

Yes, you need to put harmonic cursors on the spectrum plot, it will probably show BPFOs. It also looks like there are sidebands. I'd also extend Fmax to 2000 HZ as fluting generates more harmonics.

David