Question: 

What is Crest Factor + (High Frequency Measurement) 

Answer:

Crest Factor is the ratio of the peak value / RMS value of a time domain vibration signal. Vibration analyzers use this ratio to find bearing faults.

However, the Crest Factor method has a key limitation. The Crest Factor increases during initial bearing degradation when the peak value increases. It then decreases as the bearing damage worsens and the RMS value increases.

A low Crest Factor value could show a healthy bearing or a significantly degraded bearing.
The problem is to know the difference between the two.

The Fluke 805 and 805FC operates with a proprietary algorithm, Crest Factor+ (CF+), to overcome this limitation!

To make interpretation easy for the user, the CF+ value shows a severity range. The higher the CF+ value is, the more the bearing damage.
Table 5 shows the relationship of the values of CF+ to vibration severity.