Kurtosis - ITT i-ALERT2 Application Manual

KURTOSIS

Kurtosis is a measure of how "peaky" a data set is. (i.e. The many vibration data points recorded by the i-ALERT2 monitor
for a given sensor axis would constitute a data set) Higher values of kurtosis generally indicate increased crest factor of the
vibration signal. The crest factor is the ratio of the peak to standard deviation. Kurtosis is used for fault detection in
machinery, although it does not indicate the specific cause. Higher values indicate progressive states of fault progression.
ITT suggests utilizing Kurtosis to gauge machine condition in the same way the overall vibration amplitudes are used. As the
value trends up, it means that the machinery is spending more time vibrating at higher peak amplitudes, even though the
RMS (overall) value remains unchanged. This allows for earlier detection of faults.
To access the Kurtosis Trend, tap the small grey dot just below the trend graph. See figure 36. The Kurtosis value of the
temperature trend is likely to be very low and will skew the graph. Remove the temperature trend and zoom in to better
view the Kurtosis Trend values of each vibration axis sensor. To return to the Overall Vibration Trend, tap the small grey
button under the graph.
DEVICE NAME DEVICE NAME
Figure36: Tap the small grey button under the Trend to display Kurtosis, Kurtosis Trend with Temperature removed on right
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