Balluff BCM R15E-00 Series, User Manual

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Time window Minimum frequency
20 ms 100 Hz
100 ms 20 Hz
250 ms 8 Hz
500 ms 4 Hz
1000 ms 2 Hz
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).
t
v-RMS
a
a
a
a
Current
vibration value
Main alarm
threshold
Pre-alarm
threshold
I II III IV VI V
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).
t
v-RMS
Current vibration value
I
A
B
C
D
II III
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
3
Construction and function (continued)
BCM R15E-00 _ -DI00-_ _ , _-S4
Condition Monitoring Sensor