Thanks for the reply.
This motor is actually in our shop for recondition.
Answers to your questions below.
What caused the vibration ? Motor came to our shop due to pump only problems. Simple recondition.
Did the vibration increase smoothly over time, or did it occur suddenly? Incoming test...
We are running a 1500HP vertical motor with an upper guide bearing and a lower ball bearing. Running uncoupled we see the dominant vibration at .55 of running speed (1800) and also harmonics of the .55 peak. Even sidebands at .55 x RPM surround the running speed peak. 1X RPM vibration appears...
