Crest Factor?
Crest Factor?
(OP)
Hello everyone.
I have a problem with analysing vibration data with regard to "Crest Factor". All other measurements (Overall vibration, velocity and acceleration) seem to be well below the alarm limits. BUT when looking at the Crest Factor, its above the limits. These measurements were taken from a Soda-Ash compactor (20-tons) bearings. Its driven through a gearbox with a 400KW motor.
With all the foregoing, the Compactor was disassembled for repairs (but for a failed oil seal) and it was discovered that the DE bearing had colapsed (cracked inner and outter race as well as the bearing sleeve).
I have a problem with analysing vibration data with regard to "Crest Factor". All other measurements (Overall vibration, velocity and acceleration) seem to be well below the alarm limits. BUT when looking at the Crest Factor, its above the limits. These measurements were taken from a Soda-Ash compactor (20-tons) bearings. Its driven through a gearbox with a 400KW motor.
With all the foregoing, the Compactor was disassembled for repairs (but for a failed oil seal) and it was discovered that the DE bearing had colapsed (cracked inner and outter race as well as the bearing sleeve).





RE: Crest Factor?
If so be very careful. High crest factor signals cause fatigue out of all proportion to the RMS level.
I havee never seen a crest factor of 8 before.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Crest Factor?
So, really what does the Crest Factor tell someone?
Thanks for your help though.
By the way we are using CSI 2120. I am a graduate and have been placed with the condition monitoring team. Your help will be most appreciated.
RE: Crest Factor?
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Crest Factor?
RE: Crest Factor?
Bearings (Manufacturer and Model)
Operating Speed
Fmax for TWF collection
# Lines of resolution
Where are you making the physical vibration measurements? How often?
What kind of mount (magnet, stud, etc.)?
RE: Crest Factor?
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Crest Factor?
That doesn't explain the crest factor problem though. It does look like the crest factor calculation is about right in the bottom plot (with the "noise" contributing to the peaks).
RE: Crest Factor?
Although, not knowing much about the bearings this may not even be noise?.
Fe