SITRANS LUT400
280 Operating Instructions, 07/2019, A5E33329501-AC
11.6.3 Increase Fail-safe Timer Value
Increase the LOE Timer (2.4.2.) (Page 175) value, if fail-safe operation will not be
compromised by the larger value.
Try this only if LOE exists for short periods of time.
11.6.4 Install a Transducer with a Narrower Beam
A consistent, incorrect level reading may result due to interference echoes from the sides of
a vessel. If this occurs, try installing a longer range (narrower beam) transducer, enter the
new Transducer (2.1.6.) (Page 170) model, and (if necessary) optimize aiming and
frequency again.
Always contact Siemens service personnel before selecting a transducer to solve this type of
problem.
11.7 Fixed Reading
If the Reading is a fixed value, regardless of the transducer to material surface distance,
ensure the:
1. Transducer acoustic beam is free from obstruction.
2. Transducer is properly aimed
3. Transducer is not in contact with any metal object.
4. Material mixer (if used) is operating while the SITRANS LUT400 is operating. If it is
stopped, ensure that the mixer blade is not stopped under the transducer.
11.7.1 Obstructions in the Sound Beam
Check for (and remove if present) any acoustic beam obstruction, or relocate the transducer.
If an obstruction cannot be removed or avoided, adjust the Time Varying Threshold (TVT)
curve to reduce the Echo Confidence derived from the sound reflected by the obstruction.
Use SIMATIC PDM to adjust the TVT curve. (See TVT Shaper (2.12.4.) (Page 223) under
Echo Profile Utilities in LUT400 Communications manual
1
.)
1)
Communications for SITRANS LUT400 (HART) Manual (7ML19985NE01)
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