Setting Up A Damping Period; Setting Amplitude Threshold; Setting Process Parameters; Setting Process Safety Parameters - ABB LWT300 Series User Manual

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.
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Figure 39 The Device Setup menu
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User Guide