X20 system modules • Other functions • X20CM4810
X20 system User's Manual 3.10
2105
RmsVelEnvelope
The RMS value formed from the envelope signal of the oscillation acceleration from the configured minimum fre-
quency ("MinFrequencyEnvelope01") to the maximum frequency ("MaxFrequencyEnvelope01") of the channel.
This characteristic value is only calculated if the EnableVelocityCalculation bit (configured in the "SensorConfig01"
register) of the respective channel is set; otherwise, 0 is output.
Example:
Loose components in gears
RmsVelRaw
The RMS value formed from the raw signal of the oscillation velocity from the configured minimum frequency
("MinFrequencyRaw01") to the maximum frequency ("MaxFrequencyRaw01") of the respective channel.
This characteristic value is only calculated if the EnableVelocityCalculation bit (configured in the "SensorConfig01"
register) of the respective channel is set; otherwise, 0 is output.
Example:
Late stage bearing damage to fans
Crest factor
The crest factor is defined as a the quotient derived from the peak value and the RMS value. In a sinusoidal
oscillation, this factor amounts to
√
2. This value is also known in electrical engineering as the crest factor.
In a bearing that is operating normally, the factor is also approximately the sum of
√
2 of the crest factor. If the
condition of the bearing deteriorates, individual impacts affect the peak value and consequently raise the crest
factor. If pronounced defects are then compounded by overall wear, the RMS value in increased further. In the
worst case, the crest factor can remained unchanged or even sink again, even despite increasing damage.
1.4
Crest factor
RMS value
Peak value
C
re
st
fa
ct
or
Progressing damage/time
Figure 676: Relationship between the RMS value and peak value
Information:
When a recording of the crest factor is made, the peak and RMS values should also be recorded
CrestFactorHighFrequency
This crest factor is the ratio of the maximum amount to the RMS value formed from the high-frequency portions of
the input signal ("PeakHighFrequency" and "RmsHighFrequency") of the oscillation acceleration in the frequency
range between "HighFrequencyConfig01" (500 Hz – 2 kHz) and 10 kHz.
Example:
Early stage bearing damage to pumps
CrestFactorRaw
This crest factor is the ratio of the maximum amount to the RMS value formed from the raw signal of the oscillation
acceleration to the configured maximum frequency ("MaxFrequencyRaw01") of the respective channel.
Example:
Notification of suboptimal lubrication of gears