Trending and Alarm

Trending is the storage of vibration signatures recorded at specific time intervals and plotting the changes in vibration levels at the forcing frequencies vs. time. An upward trend in level at a forcing frequency indicates a developing problem.

The simplest way to utilize the concept of vibration trending is to establish a representative vibration spectrum of a normally operating machine as a reference or baseline, and compare this reference to spectra measured at later times on the same machine.

In trending analysis, the key is maintaining the consistency across the history of measurement. By consistency we mean the same measurement location and parameter setup, the same analysis method and the same algorithms of signal extraction. Without maintaining the consistency, the comparison will make little sense.

When taking vibration data with an FFT analyzer, or data collector, it is important to average several instantaneous spectra together to reduce random variations and the effects of extraneous noise in the measured signal.

The EDM and CoCo products provide many ways of trending analysis. All Readings can be trended, including:

1.        Acceleration rms, peak and peak-peak

2.        Velocity rms, peak and peak-peak

3.        Displacement rms, peak and peak-peak

A more advanced function is that the user can define any number of the frequency bands and the trending analysis will be applied to RMS measurement of these bands.