Tested with the EMPATH® system from the base of the tower on a GE 1.xx ESS, bearing defects were found in the drive end bearing with the automated analysis. In this case study, we will show the voltage and current signatures, but not included are the kilo-Watt and torsional spectra used to determine severity. Following are the initial spectra and findings.
Figure 1: low frequency defects including some gearbox and alignment issues.
Figure 2: High frequency spectra indicating bearing defects. The severity is determined with kilo-Watt analysis of losses across the bearing.
6330M bearing defects detected and the drive end bearing were replaced up-tower, saving well over $100k by not having to remove a severely damaged generator.
Figure 3: The low frequency spectra indicates that the gearbox issue is similar to the original which includes some high speed thrust-related problems.
Figure 4: No bearing peaks identified for the generator.
The EMPATH software automatically detected the bearing condition and it is noted that the peaks related to bearings are gone. The detection was for inner and outer race as well as a larger set of peaks associated with the bearing balls and cage.
The bearing was removed and inspected as follows:
Above – bearing shipped without cage
Inner Race Brinnelling and the ball path is off-center. Appearance shows potential thrust issues.
Outer race – false brinelling and ball tracking indicating thrust, as well. Bearing operating for a short period of time.
One of the balls extensively damaged and appears to have ‘dragged’ with balls on either side having similar but lesser damage.
Most were in excellent shape with little to no surface blemishes.
The EMPATH system was able to detect the false brinelling in the inner and outer race as well as the condition of the damaged balls. We suspect the cage was damaged, but were unable to observe.
The EMPATH data also allowed us to determine that there were conditions in both the planetary gear set and the high speed gear that led to thrusting conditions that most likely damaged the cage, trapping one or more bearing balls.
For more information on the EMPATH system contact us at info@motordoc.com