Vibration Meter
About Measurements
19
Crest Factor+ (High Frequency Measurement)
Crest Factor is the ratio of the peak value / RMS value of a
time domain vibration signal. Vibration analysts 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 Meter 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.
Table 5. Crest Factor+
CF+ Severity
0 to 5 Good
6 to 10 Satisfactory
11 to 15 Unsatisfactory
above 15 Unacceptable
The CF+ value shows for each measurement in the
Bearing field on the Meter display. Push and to toggle
between the CF+ value and the high frequency vibration
level in units of acceleration.
Quick Measurement
A quick measurement is a measurement without setup
steps to get a fast measurement for bearing vibration,
overall vibration, and temperature measurement.
To make a quick measurement:
1. Push to turn on the Meter.
The default screen appears without any machine
ID or Machine Category.
2. Push .
3. Apply compression force between the sensor tip
and test surface until the green LED turns on.
4. Wait until the green LED turns off and shows the
test result.
The overall vibration and temperature
measurements show on the display.
gqi48.bmp
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