ABB LWT300 series, Руководство пользователя

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52
User Guide
To set a median filter:
1
Select
Device Setup
>
Filtering
>
Median Filter
.
2
Press
Edit
.
3 Set the number of measurements that you want kept in the filter buffer (between 1 and 50) and
press
OK .
Setting up a damping period
The instrument damping filter is designed to smooth out measurement noise in applications with slow
dynamics (e.g., liquids with slow waves).
The damping value corresponds to the time constant (ranging from 1.0 to 99.9 s) applied to the
measurement returned by the median filter. The default value is
0.0 s
(no damping is applied).
To set a damping period:
1 Select Device Setup > Filtering > Damping .
2
Press
Edit
.
3
Set the damping period and press
OK
.
Setting amplitude threshold
The amplitude threshold is a threshold at which the instrument considers measured amplitudes as
valid. A classic use of this threshold value is when, for any reason, you have a very noisy signal and you
do not want that noise to be measured. You can achieve this by setting the amplitude threshold above
that noise level.
To set the amplitude threshold:
1
Select
Device Setup
>
Filtering
>
Amplitude Threshold
.
2
Press
Edit
.
3 Set the amplitude threshold and press OK .
Setting process parameters
Certain parameters linked to the process itself need to be configured, chiefly process safety
parameters. The following pages explain how to set these parameters.
Setting process safety parameters
Safety parameters can be configured to determine LWT behavior in cases where level measurements
become uncertain or impossible (e.g., levels getting exceedingly high or loss of signal (echoes).
Process safety parameters (as illustrated in Figure 40) are set from the Device Setup menu.
—
Figure 39
The Device Setup menu