Siemens SITRANS LG250 Operating Instructions Manual page 61

Treatment of measure-
ment errors with bulk
solids
Measurement error with constant level
Fault description Cause
Measured value Min./max. adjustment not correct
shows a too low or
Incorrect linearisation curve
too high level
0 time
Measured val- Due to the process, the amplitude of the
ue jumps towards product echo decreases
100 %
A false signal suppression was not car-
ried out
Amplitude or position of a false signal has
changed (e.g. condensation, buildup); false
signal suppression no longer matches ac-
0 time
tual conditions
PBD-51041053
The below tables show typical examples of application-related
measurement errors with bulk solids. A distinction is made between
measurement errors during:
•
Constant level
•
Filling
•
Emptying
The images in column "Error pattern" show the real level as a broken
line and the level displayed by the sensor as a continuous line.
1 Real level
2 Level displayed by the sensor
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
SITRANS LG250 - Operating Instructions
0
Rectification
Adapt min./max. adjustment
Adapt linearisation curve
Carry out a false signal suppression
Determine the reason for the changed false
signals, carry out false signal suppression,
e.g. condensation
1
2
time
61