VEGA VEGAFLEX 81 Foundation Fieldbus - Manual (Page 67)

67
9 Diagnostics and service
VEGAFLEX 81 • Foundation Fieldbus
44218-EN-130910
Fault description Error pattern Cause Rectification
4. Measured value re-
mains momentarily
unchanged during fill-
ing and then jumps to
the correct level
Level
time 0
– Turbulence on the product
surface, quick filling
– Check parameters, change if
necessary, e.g. in dosing ves-
sel, reactor
5. Measured value
jumps sporadically to
100 % during filling
Leve
l
time 0
– Changing condensation or
contamination on the probe
– Carry out a false signal sup-
pression
6. Measured value
jumps to ≥ 100 % or
0 m distance
Leve
l
time 0
– Level echo is no longer
detected in the close range
due to false signals in the close
range. The sensor goes into
overfill protection mode. The
max. level (0 m distance) as
well as the status message
"Overfill protection" are output-
ted.
– Eliminate false signals in the
close range
– Check installation conditions
– If possible, switch off the func-
tion "Overfill protection"
Measurement error during emptying
Fault description Error pattern Cause Rectification
7. Measured value re-
mains unchanged in
the close range during
emptying
Level
time 0
– False echo larger than the level
echo
– Level echo too small
– Eliminate false signals in the
close range
– Remove contamination on the
probe. After having removed
the source of the false signals,
the false signal suppression
must be deleted.
– Carry out a new false signal
suppression
8. Measured value re-
mains reproducible
in one position during
emptying
Level
time 0
– Stored false signals in this
position are larger than the
level echo
– Delete false signal memory
– Carry out a new false signal
suppression
The below tables show typical examples for application-relevant
measurement errors with bulk solids. 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.
Treatment of measure-
ment errors with bulk
solids