VEGA VEGAFLEX 86 Foundation Fieldbus - Manual (Page 69)

69
9 Diagnostics and service
VEGAFLEX 86 • Foundation Fieldbus
44233-EN-130910
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.
1
2
Level
time 0
1 Real level
2 Level displayed by the sensor
Notes:
•
Wherever the sensor displays a constant value, the reason could
also be the fault setting of the current output to "Hold value"
•
In case of a too low level indication, the reason could be a line
resistance that is too high
Treatment of measure-
ment errors with bulk
solids