Just wondering if anyone has came across an issue in which is shown a different fault frequency on each end of a motor. I am using an UP10000, and the standard UE Systems software. I have attached 2 sound wave files. One end shows a 245Hz fault and the other end shows a 295 Hz fault. There is an electrical quality to the sound wave files also. The fault frequencies present are nowhere near any possible RPM. Any thoughts? RPM is 3570 on the motor tag.
VFD on motor?
Open frame air cooled motor?
What is spectrum resolution?
60-Hz line frequency?
Motor is AC on a soft start, open air cooled 60 Hz.
I have worked on high voltage 3600-rpm open frame motors on boiler feed water pumps that were in a dusty environment. The high ultrasound was caused by arcing of the dust in the stator frame. These were not TEFC motors. Did you also measure vibrations and do spectrum analysis. Try not to relay on one technology before making an important diagnosis.
Have you lubricated the bearings while using the ultrasound meter?
The bearings were lubricated using the UP 10000 so as not to over lubricate. The most recent vibe report from Nov. of last year indicated no issues with motor. If the dust you had was arcing, would that not have shown up as a 60 Hz repeating fault on your motor? I can see a slight 60 Hz fault in the MOB, but why the strange "spikes"? I can get the bearing fault calculator in the software to line up an inner race fault on the MIB at a believable RPM. However, if I try to use the same RPM on the other end of the motor to try to determine the fault using the bearing fault calculator the RPM would have to go up to an impossible number, well above tag RPM. This is my dilemma. The infrared proves inconclusive also.
Vibrations have not been measured for about 5-months. What are you waiting for? How long ago was lubrication done? I am not familiar with UE-System software, but perhaps there is a match to a harmonic of a fault frequency. Another problem is the bearing may not be what you think it is. Another problem is that the bearing may be loose on shaft or in housing, so fault frequencies are not correct do to spinning races.
Regarding the 60-Hz from your diagnostic chart -- arcing produces a lot of frequencies, and may not be as simple as indicated on chart.
Thanks for your input Walt, I appreciate it.
Again I don't know your software or analysis settings, but I suggest taking several spectrum averages to detect periodic bearing frequencies from all of the random noise that is present from impacting and friction.
Is it possible there are two different bearings in this motor? Causing two separate fault frequencies? I agree, where are the vibration spectra?
Bearings are same on each end of this motor. Vibe analysis will be performed at the end of this month. The inspections I do are with ultrasound and infrared only. To get the bearing faults to align with the correct Hz in the software, the motor would have to running at TWO different RPM's. THUS my question.
Tom, why don’t we just wait until we see the vibration signatures.