Siemens SITRANS LUT400 - Page 224

SITRANS LUT400
222 Operating Instructions, 07/2019, A5E33329501-AC
Auto False Echo Suppression (2.12.3.1.)
Used together with Shaper Mode and Auto False Echo Suppression (Page 293) to screen
out false echoes in a vessel with known obstructions. A ’learned TVT’ (time varying
threshold) replaces the default TVT over a specified range. See Shaper Mode and Auto
False Echo Suppression (Page 293) for a more detailed explanation.
Note
•
Make sure material level is below all known obstructions when Auto False Echo
Suppression is used to learn the echo profile. (An empty or almost empty vessel is
recommended.)
•
Note the distance to material level when Auto False Echo learns the environment. Set
Auto False Echo Suppression Range to a shorter distance to avoid the material echo
being screened out.
•
Set Auto False Echo Suppression and Auto False Echo Suppression Range during
startup, if possible.
•
All other tuning and filter adjustments (such as Narrow Echo Filter (2.12.2.4.) (Page 221
),
Reform Echo (2.12.2.3.) (Page 221), Hover Level (2.12.3.3.) (Page 223), and so on.)
should be completed prior to using Auto False Echo Suppression to ensure that the
learned profile is representative.
1. Determine Auto False Echo Suppression Range. Measure the actual distance from the
sensor reference point to the material surface using a rope or tape measure.
2. Subtract 0.5 m (20") from this distance, and use the resulting value.
To set Auto False Echo Suppression via SIMATIC PDM:
Open the menu Device – Echo Profile Utilities and click on the tab Auto False Echo
Suppression. (For more detailed instructions see Auto False Echo Suppression in
LUT400 Communications manual
1
.)
To set Auto False Echo Suppression via the local push buttons:
Options
OFF
Default TVT will be used.
*
ON
'Learned’ TVT will be used.
LEARN
'Learn’ the TVT.
3. Navigate to Setup (2.) (Page 168) > Signal Processing (2.12.) (Page 218) > TVT Setup
(2.12.3.) (Page 221) > Auto False Echo Suppression Range (2.12.3.2.) (Page 223), and
enter the value calculated in step 2).
4. Navigate to Setup (2.) (Page 168) > Signal Processing (2.12.) (Page 218) > TVT Setup
(2.12.3.) (Page 221
) > Auto False Echo Suppression (2.12.3.1.), and press RIGHT arrow
to open Edit Mode.
5. Select Learn. The device will automatically revert to On (Use Learned TVT) after a few
seconds.
1.
Communications for SITRANS LUT400 (HART) Manual (7ML19985NE01)