Managing Lost Echoes - ABB LWT300 series User Manual

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Figure 35 Blocking and safety distances
Sensor reference
point
Setting a safety distance
The safety distance is a distance where you can take measurements, at levels preceding the blocking
distance. Essentially, this is the distance between the sensor reference point and the 100 % full/span
value, in case you might want to be informed when such levels are reached.
To set a safety distance:
1 Select Device Setup > Safety Setting > Safety distance.
2 Press Edit.
3 Set the necessary safety distance and press OK.
Activating a safety distance related alarm
You can raise an alarm when the safety distance threshold is reached.
To to so:
1 Select Device Setup > Safety Setting > Safety Dist. Reaction.
2 Press Edit.
3 Highlight Alarm and press OK.

Managing lost echoes

A lost echo happens when your instrument loses the signal returning to the sensor. You can set the
parameters that help your instrument manage such situations.
Period
The lost echo period is the time period during which the instrument waits before reacting.
To set a lost echo period:
1 Select Device Setup > Safety Setting > Echo Lost Period.
2 Press Edit.
3 Set the period of time for lost echoes and press OK.
Nozzle length
Blocking distance
Safety distance
Configuring the instrument
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