VEGA VEGAPULS 68 (≥ 2.0.0 - ≥ 4.0.0) Profibus PA - Manual (Page 60)

60
9 Diagnosis, Asset Management and service
VEGAPULS 68 • Profibus PA
36537-EN-130205
Measurement error during filling
Fault description Error pattern Cause Rectification
3rd measured value
jumps towards 0 % du-
ring filling
Level
time 0
– Amplitude of a multiple echo
(vessel top - product surface) is
larger than the level echo
– Check parameter "Application",
especially vessel top, product
type, dished end, high dielectric
figure, adapt if necessary
– The level echo cannot be distin-
guished from the false echo at
a false echo position (jumps to
multiple echo)
– Remove/reduce false echo:
minimize interfering installati-
ons by changing the polariza-
tion direction
– Chose a more suitable installa-
tion position
– Transverse reflection from an
extraction funnel, amplitude of
the transverse reflection larger
than the level echo
– Direct sensor to the opposite
funnel wall, avoid crossing with
the filling stream
4th measured va-
lue fluctuates around
10 … 20 %
Level
time 0
– Various echoes from an uneven
product surface, e.g. a material
cone
– Check application parameter
"Medium type" and adapt, if
necessary
– Optimize installation position
and sensor orientation
– Reflections from the product
surface via the vessel wall
(deflection)
– Select a more suitable
installation position, optimize
sensor orientation, e.g. with a
swivelling holder
5. measured value
jumps sporadically to
100 % during filling
Level
time 0
– Varying condensation or conta-
mination on the antenna
– Carry out a false signal
suppression or increase false
signal suppression with con-
densation/contamination in the
close range by editing
– With bulk solids use radar sen-
sor with purging air connection
or flexible antenna cover
Measurement error during emptying
Fault description Error pattern Cause Rectification
6th 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
– Remove false echoes in the
close range. Check: Antenna
must protrude out of the socket
– Remove contamination on the
antenna
– Minimize interfering installati-
ons in the close range by chan-
ging the polarization direction
– After removing the false
echoes, the false signal
suppression must be deleted.
Carry out a new false signal
suppression