Order Tracking with SKF @ptitude Analyst

If you are going to collect vibration measurements on a variable speed machine that has no stable speed (fig. 1), you will probably end up with spectra that are not sufficient. If a normal FFT is taken during a speed variation, the peaks in the spectrum will smear out; they will either be smaller and wider or completely disappear (fig. 2).

This is because the number of samples per time unit will always be the same independent of the speed. For example, it will be difficult to find peaks from bearing frequencies in the normal spectrum collected during a speed variation.

When measuring vibrations on a variable speed machine, there is a need to constantly follow the speed and adjust the number of samples to the speed. This is done with order tracking in the SKF Multilog On-line System IMx and SKF @ptitude Analyst on-line systems.