59
9 Diagnostics and service
VEGAFLEX 83 • 4 … 20 mA/HART - two-wire
41834-EN-120726
9.4 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
– Wrong 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 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
9.4 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 end
– 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.
– Remove false signals in the
close range
– Check installation conditions
– If possible, switch off the func-
tion "Overfill protection"