Recently a 550 kw motor bearings were replaced due to an increase in the NDE bearing Peakvue. The vibration was 1.2 mm/s rms.
After overhaul the solo run was taken the vibration increased to 2.8 mm/s rms. This motor bearing was changed for the first time 18 years. It is being felt that the vibrations should be brought back to the previous level.
The dominant frequency in horizontal is 1 X - 2.7 mm/s and a peak at 2 X about 0.2 mm/s.
In the vertical direction - vibration is 1 mm/s
Cross channel phase readings were taken.
NDE H vs V - is 172 Deg
DE H vs V - is 178 deg
NDE Horizontal vs DE Horizontal - is 0 deg (in phase)
Immediate suspicion was soft foot - the same was corrected (0.2 mm was observed in one of the feet was brought down to 0.04 mm) but to avail.
I am not convinced that it could be unbalance based on the phase readings.
The axial vibration levels are 0.74 mm/s
Axial DE left vs right - is 76 deg
Axial top vs bottom - is (-)17 deg
What could be the problem?