Siemens SITRANS LUT400, Руководство по эксплуатации

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Page 184 SITRANS LUT400 (HART) – OPERATING INSTRUCTIONS A5E33329501
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The submergence condition remains in effect until the transducer is no
longer submerged. A valid echo must then be detected before the LOE
Timer expires or the device will enter fail-safe condition (see
2.4. Fail-
Safe
).
2.12.3. TVT Setup
2.12.3.1. Auto False Echo Suppression
Used together with Auto False Echo Suppression Range (2.12.3.2.) 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 on page 260
for a more detailed explanation.
a) 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.
b) 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
.)
Note: Default settings in the parameter tables are indicated with an asterisk (*)
unless explicitly stated.
Notes:
• 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
2.12.2.4. Narrow Echo
Filter
,
2.12.2.3. Reform Echo
,
2.12.3.3. Hover Level
, etc.) should be
completed prior to using Auto False Echo Suppression to ensure that
the learned profile is representative.
1.
Communications for SITRANS LUT400 (HART) Manual (7ML19985NE01)