Balluff BCM R15E-00 DI00 S4 Serie Betriebsanleitung Seite 59

BCM R15E-00 _ -DI00-_ _ , _-S4
Condition Monitoring Sensor
3
Construction and function (continued)
Time window
20 ms
100 ms
250 ms
500 ms
1000 ms
Tab. 3-3: Minimum permitted frequency in the signal for a specified
time window
Vibration velocity
The sensor calculates the vibration velocity of the three
axes from the measured acceleration values.
The following values for all three axes as well as the
magnitude are determined by the vibration velocity signal:
– RMS value
– Peak-to-peak value
The calculation and evaluation take place within the
configured vibration module time window.
For the X, Y and Z axes, the sensor also stores the
following statistical values that are calculated over the time
window:
– Mean
– Standard deviation
– Crest factor
– Skewness
– Kurtosis
In addition, the sensor can detect when pre-alarm and
main-alarm thresholds are exceeded. To increase the
stability of events, a time interval (EVENT RESPONSE
DELAY) can be defined. This time interval defines how long
a threshold must be exceeded for in order to trigger an
alarm (see Fig. 3-5).
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Minimum frequency
100 Hz
20 Hz
8 Hz
4 Hz
2 Hz
v-RMS
Main alarm
threshold
a
I II III
a
EVENT RESPONSE DELAY
I Pre-alarm threshold exceeded
II Pre-alarm triggered
III Pre-alarm threshold underrun (pre-alarm remains active,
because the duration of the underrun is too short)
IV Main alarm threshold exceeded (main-alarm remains
deactived, because the duration of the exccedance is too
short)
V Main alarm threshold exceeded
VI Main alarm triggered
Fig. 3-5: Pre-alarm and main-alarm thresholds of vibration velocity
detection
The sensor also supports classification of vibration
amplitudes. This takes place according to levels of severity
(SEVERITY ZONE) based on the largest v-RMS value of
the three axes and the magnitude (see Fig. 3-6).
v-RMS
I
D Risk of machine damage
C Restricted further operation
B Continuous operation without restrictions possible
A Newly commissioned machine
I Zone limit A/B exceeded
II Zone limit B/C exceeded
III Zone limit C/D exceeded
Fig. 3-6: Vibration velocity – classification of vibration amplitudes
Current
a
vibration value
a
a
Pre-alarm
threshold
t
IV V VI
Current vibration value
D
C
B
A
II III t
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