Siemens SITRANS L Operating Instructions Manual page 43

Diagnostics and troubleshooting
9.5 Treatment of measurement errors
The images in column ""Error description" show the actual level as a dashed line and
the output level as a solid line.
1
2
Note
If the output level is constant, the cause could also be the fault setting of the current
output to ""Hold value".
If the level is too low, the reason could be a line resistance that is too high
Fault description
Measured value shows a
too low or too high level
Measured value jumps
towards 100 %
Fault description
Measured value remains
unchanged during filling
36
Real level
Level displayed by the transmitter
Cause
Min./max. adjustment not correct
Incorrect linearization curve
Due to the process, the amplitude
of the level echo sinks
A auto false echo suppression was
not carried out
Amplitude or position of a
false signal has changed (e.g.
condensation, buildup); auto
false echo suppression no longer
matches actual conditions
Cause
False signals in the close range too
big or level echo too small
Strong foam or vortex generation
Max. adjustment not correct
Rectification
Adapt min./max. adjustment
Adapt linearization curve
Carry out a auto false echo
suppression
Determine the reason for the
changed false signals, carry out
auto false echo suppression, e.g.
with condensation.
Rectification
Eliminate false signals in the close
range
Check measuring point: Antenna
should protrude out of the threaded
mounting nozzle, possible false
echoes through flange nozzle?
Remove contamination on the
antenna
In case of interferences due to
installations in the close range,
change polarisation direction
Operating Instructions, 10/2021, 62705-76-01
SITRANS LR100