Vega VEGAPULS 64 Operating Instructions Manual page 63

Measurement error with constant level
Fault description
1. Measured value
shows a too low or too
high level
2. Measured value
jumps towards 0 %
3. Measured value
jumps towards 100 %
VEGAPULS 64 • 4 ... 20 mA/HART - two-wire
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"
•
If the level indication is too low, the reason could be a line resist-
ance that is too high
Error pattern Cause
– Min./max. adjustment not
correct
– Incorrect linearization curve
0
time
– Installation in a bypass tube or
standpipe, hence running time
error (small measurement error
close to 100 %/large error close
to 0 %)
– Multiple echo (vessel top,
product surface) with amplitude
higher than the level echo
0
time
– Due to the process, the ampli-
tude of the level echo sinks
– A false signal suppression was
not carried out
0
time
– Amplitude or position of a false
signal has changed (e.g. con-
densation, buildup); false signal
suppression no longer matches
actual conditions
9 Diagnosis, asset management and service
0
Rectification
– Adapt min./max. adjustment
– Adapt linearization curve
– Check parameter "Application"
– Check parameter "Application",
– Carry out a false signal sup-
– Determine the reason for the
1
2
time
with respect to vessel form,
adapt if necessary (bypass,
standpipe, diameter)
especially vessel top, type of
medium, dished bottom, high
dielectric constant, and adapt if
necessary
pression
changed false signals, carry out
false signal suppression, e.g.
with condensation
63