Siemens SITRANS LR120 Modbus Operating Instructions Manual page 45

Diagnostics and troubleshooting
9.4 Treatment of measurement errors
Fault description
Fault description
Measured value shows a
too low or too high level
Measured value jumps
towards 100 %
Fault description
Measured value jumps
towards 0 % during filling
Measured value fluctuates
around 10 ... 20 %
38
Cause
Cause
Min./max. adjustment not correct
Incorrect linearization curve
Due to the process, the amplitude
of the product echo decreases
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
The level echo cannot be
distinguished from the false signal
at a false signal position (jumps to
multiple echo)
Transverse reflection from an
extraction funnel, amplitude of the
transverse reflection larger than the
level echo
Various echoes from an uneven
medium surface, e.g. a material
cone
Reflections from the medium
surface via the vessel wall
(deflection)
Rectification
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
Remove/reduce false signal:
minimize interfering installations by
changing the polarization direction
Chose a more suitable installation
position
Direct transmitter to the opposite
funnel wall, avoid crossing with the
filling stream
Check parameter "Material Type"
and adapt, if necessary
Optimize installation position and
transmitter orientation
Select a more suitable installation
position, optimize transmitter
orientation, e.g. with a swivelling
holder
Operating Instructions, 10/2022, 62709-76-01, A5E49829030
SITRANS LR120 Modbus