Siemens SITRANS LUT400, Operating Instructions Manual

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Page 246 SITRANS LUT400 (HART) – OPERATING INSTRUCTIONS A5E33329501
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Set the SITRANS LUT400 to Ignore the Bad Echo
If the preceding remedies have not fixed the problem, the false echo has to be ignored.
If the Echo is Close to the Transducer
If there is a static, incorrect, high level reading from the SITRANS LUT400 there is
probably something reflecting a strong echo back to the transducer. If the material level
never reaches that point extend the
2.2.4. Near Range
to a distance to just past the
obstruction.
Adjust the TVT to Ignore the Echo
Use
2.12.3.1. Auto False Echo Suppression
. If this does not correct the problem, use
2.12.4.
TVT Shaper
to manually shape around false echoes.
Wrong Reading
If the Reading is erratic, or jumps to some incorrect value periodically, ensure the:
1. Surface monitored is not beyond the SITRANS LUT400’s programmed range or the
transducer’s maximum range.
2. Material is not falling into the transducer’s acoustic beam.
3. Material is not inside the blanking distance (near range) of the transducer.
Types of Wrong Readings
If a periodic wrong Reading is always the same value, see “Fixed Reading” on page 245
.
If the wrong Reading is random, ensure the distance from the transducer to the material
surface is less than
2.2.5. Far Range
value plus one meter (i.e. ensure you are still within
the measurement range programmed in the device). If the material/object monitored is
outside this range, increase
2.2.5. Far Range
as required. This error is most common in
OCM applications using weirs.
Liquid Splashing
If the material monitored is a liquid, check for splashing in the vessel. Enter a lower
Response Rate
value (see page 42) to stabilize the Reading, or install a stilling well.
(Contact Siemens representative.)
Adjust the Echo Algorithm
Use SIMATIC PDM to view echo profiles and make adjustments to the
Algorithm
parameter. See
2.12.2.1. Algorithm
on page 182 for details.
If the "TRACKER” algorithm is used and narrow noise spikes are evident on the Echo
Profile, widen the
2.12.2.4. Narrow Echo Filter
. Also, if the true echo has jagged peaks, use
2.12.2.3. Reform Echo
.
If multiple echoes appear on the Echo Profile, typical of a flat material profile (especially if
the vessel top is domed), use the “TF ” (True First) algorithm.
Should a stable measurement still not be attainable, contact Siemens representative.