Vega VEGAPULS 11 - Treatment of Measurement Errors

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10 Diagnostics and servicing
VEGAPULS 11 • Two-wire 4 … 20 mA
58350-EN-200806
Liquids: Measurement error at constant level
Fault description Cause Rectication
Measured value shows a too
low or too high level
Level
time
0
Min./max. adjustment not correct Adapt min./max. adjustment
Incorrect linearization curve Adapt linearization curve
Measured value jumps to-
wards 100 %
Level
time
0
Due to the process, the amplitude of the
level echo sinks
A false signal suppression was not car-
ried out
Carry out a false signal suppression
Amplitude or position of a false signal
has changed (e.g. condensation, build-
up); false signal suppression no longer
matches actual conditions
Determine the reason for the changed
false signals, carry out false signal sup-
pression, e.g. with condensation.
Liquids:Measurementerrorduringlling
Fault description Cause Rectication
Measured value remains un-
changedduringlling
Level
time
0
False signals in the close range too big
or level echo too small
Strong foam or vortex generation
Max. adjustment not correct
Eliminate false signals in the close
range
Check measuring point: Antenna should
protrude out of the threaded mounting
socket, possible false echoes through
angesocket?
Remove contamination on the antenna
In case of interferences due to instal-
lations in the close range, change
polarisation direction
Create a new false signal suppression
Adapt max. adjustment
Measured value jumps to-
wards0%duringlling
Level
time
0
The level echo cannot be distinguished
from the false signal at a false signal po-
sition (jumps to multiple echo)
In case of interferences due to instal-
lations in the close range: Change
polarisation direction
Chose a more suitable installation po-
sition
Measured value jumps to-
wards100%duringlling
Level
time
0
Due to strong turbulence and foam gen-
erationduringlling,theamplitudeof
the level echo sinks. Measured value
jumps to false signal
Carry out a false signal suppression