Siemens SITRANS LG270 Operating Instructions Manual page 64

Measurement error during filling
Fault description
Measured value
jumps towards 0 %
during filling
0
time
Measured value
fluctuates around
10 ... 20 %
0 time
Measured value
jumps sporadically to
100 % during filling
0
time
Measurement error during emptying
Fault description
Measured value re-
mains unchanged in
the close range dur-
ing emptying
0
time
Measured value
jumps sporadically
towards 100 % dur-
ing emptying
0
time
64
Cause
Amplitude of a multiple echo (vessel top
- product surface) is larger than the lev-
el echo
The level echo cannot be distinguished from
the false signal at a false signal position
(jumps to multiple echo)
Transverse reflection from an extraction fun-
nel, amplitude of the transverse reflection
larger than the level echo
Various echoes from an uneven product
surface, e.g. a material cone
Reflections from the product surface via the
vessel wall (deflection)
Varying condensation or contamination on
the antenna
Cause
False signal larger than the level echo
Level echo too small
Varying condensation or contamination on
the antenna
SITRANS LG270 - Operating Instructions
Rectification
Check parameter "Application", especially
vessel top, type of medium, dished bottom,
high dielectric constant, and adapt if nec-
essary
In case of interferences due to installations
in the close range: Change polarisation di-
rection
Chose a more suitable installation position
Direct sensor to the opposite funnel wall,
avoid crossing with the filling stream
Check parameter "Material Type" and
adapt, if necessary
Optimize installation position and sensor
orientation
Select a more suitable installation position,
optimize sensor orientation, e.g. with a swiv-
elling holder
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 sensor with purg-
ing air connection or flexible antenna cover
Rectification
Eliminate false signals in the close range.
Check: Antenna must protrude out of the
socket
Remove contamination on the antenna
In case of interferences due to installations
in the close range: Change polarisation di-
rection
After eliminating the false signals, the false
signal suppression must be deleted. Carry
out a new false signal suppression
Carry out false signal suppression or in-
crease false signal suppression in the close
range by editing
With bulk solids use radar sensor with purg-
ing air connection or flexible antenna cover
PBD-51041506