VEGA VEGAFLEX 81 4 … 20 mA_HART - four-wire Coax probe - Manual (Page 61)

61
9 Diagnostics and service
VEGAFLEX 81 • 4 … 20 mA/HART - four-wire
42280-EN-130314
Fault description Error pattern Cause Rectification
2. Measured value
jumps towards 100 % Level
time 0
– Due to the process, the ampli-
tude of the product echo sinks
– A false signal suppression was
not carried out
– Carry out false signal suppres-
sion
– 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
Measurement error during filling
Fault description Error pattern Cause Rectification
3. Measured value re-
mains in the area of the
bottom during filling
Level
time 0
– Echo from the probe end larger
than the product echo, for
example, with products with
ε
r
< 2.5 oil-based, solvents, etc.
– Check application parameter
"Medium" and "Vessel height",
adapt if necessary
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 application parameters,
change if necessary, e.g. in
dosing vessel, reactor
5. Measured value
jumps sporadically to
100 % during filling
Level
time 0
– Varying condensation or con-
tamination on the probe
– Carry out false signal suppres-
sion
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