Siemens sitrans LU10 - Page 104

Page 100 SITRANS LU10 – INSTRUCTION MANUAL 7ML19985AN02
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Troubleshooting Guide
If increasing Near Blanking is unacceptable (the transducer cannot be mounted higher)
see Auxiliary Transducer (P725). Otherwise, the TVT Curve must be raised in the area of
the false echo.
Connect an oscilloscope to the SITRANS LU10, (see
Enhancement Parameters Scope
Displays, P810). Adjust the TVT Start Min (P833), TVT Start Duration (P834), and TVT Slope
Min (P835) slightly.
Continue making minor TVT Curve adjustments and taking new measurements while
observing the Echo Marker position until the Echo Lock Window repeatedly locks onto
the true echo. Verify the false echo is still ignored, regardless of the vessel material level,
or empty / fill activity.
Wrong Reading
If the Reading is erratic, or jumps to some incorrect value periodically, ensure the
following:
1. Material (object) surface monitored is not beyond the transducers maximum
range.
2. Material is not falling in the transducer sound beam.
3. Material ( P002 ) value matches the material monitored.
4. Measurement Response ( P003 ) is not set too fast.
5. Transducer ( P004 ) type entered matches the transducer used.
If the periodic incorrect value is always the same, see Fixed Reading. If the incorrect
value seems to be random, ensure the material surface to transducer distance is less
than the Empty value entered plus 20%. If the material / object monitored is outside this
distance, increase Range Extension (P801) as required.
If the material monitored is a liquid, check for splashing in the vessel. Increase
Measurement Response as required to stabilize the Reading, or install a stilling well
(contact Siemens Milltronics or your local distributor).
Access the Noise (P807) parameter. If the peak value jumps wildly, verify the transducer
cables are run in grounded metal conduit; separate from other wiring, and transducer
cable shields are connected to the SITRANS LU10 shield terminals and not to ground
elsewhere.
If the SITRANS LU10 is mounted in close proximity to (or transducer cables run near
those of) another ultrasonic level monitor, see Level System Sync (P726).
Temporarily disable nearby SCR control drives, high voltage or current contactors. If the
condition disappears, move the SITRANS LU10 to another location.
Set Echo Lock (P711) to "max verification" (response to material level changes may be
slowed somewhat).
Increase the Confidence Threshold (small amounts at a time) while observing the results.
If performance is not improved return the Confidence Threshold to the preset value.
Connect an oscilloscope to the SITRANS LU10, (see
Enhancement Parameters Scope
Displays, P810). While monitoring the Echo Marker, select the Algorithm (P820) best
suited to the material / conditions.