Siemens SITRANS LUT400, Operating Instructions Manual

Page: 558 / 601

A5E33329501 SITRANS LUT400 (HART) – OPERATING INSTRUCTIONS Page 245
m
mmmm
Tr
oub
leshoot
in
g
Increase Fail-safe Timer Value
Increase the
2.4.2. LOE Timer
value, if fail-safe operation will not be compromised by the
larger value.
Try this only if LOE exists for short periods of time.
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
2.1.6. Transducer
model, and (if necessary) optimize aiming and frequency again.
Always contact Siemens service personnel before selecting a transducer to solve this
type of problem.
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.
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
under
Echo Profile Utilities
in
LUT400 Communications manual
1
.
)
Nozzle Mountings
If the transducer is mounted on or in a nozzle, grind smooth any burrs or welds on the
inside or open end (the end that opens into the vessel). If the problem persists, install a
larger diameter or shorter length nozzle, bevel the inside of the bottom end, or cut the
open end of the nozzle at a 45° angle.
See the transducer manual for complete mounting instructions.
If the mounting hardware is over tightened, loosen it. Over tightening changes the
resonance characteristics of the transducer and can cause problems.
1.
Communications for SITRANS LUT400 (HART) Manual (7ML19985NE01)