Table 5: Lower limit of the frequency range for Speed signal type [Hz]
Block length [ms]
Lower limit of the frequency range for Speed
signal type [Hz]
20
320
40
160
80
80
160
40
320
20
640
10
1280
10
Bandpass filter (Index 4478)
Which frequency ranges are to be considered can be selected using a bandpass filter.
Restricting the frequency range can, depending on the application and the component
to be monitored, provide a more precise indication of an error.
If no bandpass filter is applied, the frequency range from 0 to 3,200 Hz is taken into
account. When using the “ISO10816 limit values" (
see "Limit values based on ISO
10816 (Index 4534-4536)", page 33
), the monitored frequency range is limited to
10 ... 1,000 Hz according to the specifications of the standard.
4.3.3
Trigger (Index 4474-4475)
Condition monitoring
requires repeatable conditions and corresponding data quality. Only
with these two prerequisites can changes in condition over time and deviation over the
course of time be detected. In applications with continuous uniform speeds, such as
pumps or fans driven by asynchronous motors, this is usually the case. The vibration
should always remain the same, no matter at what point in time it is measured during
operation. This is not the case with dynamic, non-uniform movements such as punches,
presses or motors with changing loads. Here, the data must be recorded at a specific
point in time at which a constant vibration pattern is expected (e.g. always the same
point in time in the punching process).
NOTE
When using the trigger, the number of blocks for averaging (Index 4477 Subindex 4)
should be considered and set to 1 if necessary. With a block number of 4, for example,
the trigger must fire 4 times before the values are output.
Trigger settings (Index 4474)
Recording starts with an automatic trigger immediately after the boot process. The
data blocks and the evaluations then line up seamlessly and the indication values are
updated according to the total block length (
). This is the factory
setting, which is suitable for uniform, permanent movements.
If, on the other hand, recording of data is to be started at an exactly defined time, it
can be triggered via an index or via pin 2. The selection of the trigger source (automatic,
index or pin 2) is done in Index 4474, Subindex 1. If required, this trigger can be
delayed by an adjustable time (Index 4474, Subindex 3).
Trigger via an ISDU
Index 4475 can be used to trigger by writing a 1 if trigger source ISDU is selected in
Index 4474, Subindex 1.
PRODUCT DESCRIPTION
4
8028041/2022-08-16 | SICK
O P E R A T I N G I N S T R U C T I O N S | MPB10
15
Subject to change without notice
