67
PBD-51041388
SITRANS LG250 - Operating Instructions
46201-EN-150424
Error
Cause
Rectification
Current sig-
nal greater than
22 mA or less
than 3.6 mA
Electronics mod-
ule in the sensor
defective
Exchange the instrument or send it in
for repair
The below tables show typical examples for application-relevant
measurement errors. There are two measurement errors:
•
Constant level
•
Filling
•
Emptying
The images in column "
Error pattern
" show the real level with a bro-
ken line and the level displayed by the sensor as a continuous line.
1
2
Level
time
0
Fig. 27: The broken line 1 shows the real level, the continuous line 2 shows the
level displayed by the sensor
Note:
•
Wherever the sensor displays a constant value, the reason could
also be the fault setting of the current output to "
Hold value
"
•
If the level indication is too low, the reason could be a line resist-
ance that is too high
Measurement error with constant level
Fault description
Error pattern
Cause
Rectification
1. Measured value
shows a too low or too
high level
Level
time
0
–
Min./max. adjustment not
correct
– Adapt min./max. adjustment
– Incorrect linearization curve
– Adapt linearization curve
– Running time error (small
measurement error close to
100 %/serious error close to
0 %)
– Repeat setup
2. Measured value
jumps towards 100 %
Level
time
0
– Due to the process, the
amplitude of the product echo
decreases
– A false signal suppression was
not carried out
– Carry out a false signal sup-
pression
– Amplitude or position of a
false signal has changed (e.g.
buildup); false signal suppres-
sion no longer matches
– Determine the reason for the
changed false signals, carry out
false signal suppression, e.g.
with buildup
Treatment of measure-
ment errors