2. Measurements and analysis of diagnostic signals.
What is the necessary stability of the bearing rotation speed
for qualitative diagnostics?
The question was asked by a post graduate student of the Alabama University.
The question is answered by
Alexej V. Barkov:
There are four main requirements for the rotation speed
stability to make its qualitative diagnostics:
The stability of rotation frequency during one
The stability of rotation frequency during 5-10 revolutions.
The stability of rotation frequency during the whole period of
measurement (50-100 revolutions).
The reproducibility of the rotation frequency from one measurement to
The optimal requirement - the stability 1% during all the measurements
(according to item 3) and the reproducibility - 20% (item 4).
Some special techniques we use when the stability during 5-10 revolutions is
1-2% (item 2) and the stability according to item 3 - 20%.
We can also make the diagnostics when the stability is 1-2% during 5-10
revolutions doing the interruptions after each envelope spectrum. The periods
between the measurements can be unlimited.
Potentially it is possible to make the diagnostics when the stability for one
revolution is 1-2%, the stability during the whole measurement - 50% and the
reproducibility (item 4) about 2 times. But we do not have such methods yet.