Vega VEGAPULS 68 Operating Instructions Manual - page 22
Apart from the medium, the vessel shape can also influence the
measurement. To adapt the sensor to these measuring conditions, this
menu item offers different options depending on whether liquid or solid
is selected. With "Solid" these are "Silo" or "Bunker", with "Liquid",
"Storage tank", "Stilling tube", "Open vessel" or "Stirred vessel".
Vessel form
Silo
Enter the requested parameter via the appropriate keys, save your
settings and jump to the next menu item with the [->] key.
A linearization is necessary for all vessels in which the vessel volume
does not increase linearly with the level - e. g. with a cylindrical or
spherical tank - and the indication or output of the volume is required.
Corresponding linearization curves are preprogrammed for these
vessels. They represent the correlation between the level percentage
and vessel volume. By activating the appropriate curve, the volume
percentage of the vessel is displayed correctly. If the volume should
not be displayed in percent but e.g. in l or kg, a scaling can be also set
in the menu item "Display".
Linearisation curve
linear
Enter the requested parameter via the appropriate keys, save your
settings and jump to the next menu item with the [->] key.
False reflections by vessel installation can impair the measurement as
described in chapter "Mounting". A false echo storage detects and
marks these false echoes, so that they are no longer taken into
account for the level measurement. To detect these interfering
reflections over the complete measuring range, the gating out of false
echoes should be carried out with empty vessel.
Information:
However, the measuring signals are not damped by the product in
completely empty, closed metal vessels. Due to this, considerable
multiple reflections can be caused by which the noise level can
increase. In such vessels, it is recommended to carry out the gating
out of false echoes with part filling.
Gating out of false signals
Change now?
Vessel form
Linearisation curve
Gating out of false sig-
nals
VEGAPULS 68 • 4 … 20 mA/HART two-wire
41
6 Set up with the indicating and adjustment module PLICSCOM
29261
-EN
-090305
Proceed as follows:
1 Move from the measured value display to the main menu by
pushing [OK].
2 Select the menu item "Service" with [->] and confirm with [OK].
Now the menu item "False signal suppression" is displayed.
3 Confirm "False signal suppression - Change now" with [OK] and
select in the below menu "Create new". Enter the actual distance
from the sensor to the product surface. All false signals in this area
are detected by the sensor and saved after confirming with [OK].
Note:
Check the distance to the product surface, because if an incorrect (too
large) value is entered, the existing level will be saved as false signal.
The filling level would then no longer be detectable in this area.
The menu item "Extended setting" offers the possibility to optimise
VEGAPULS 68 for applications in which the level changes very
quickly. For this reason, select the function "Quick level change > 1 m/
min.".
Extended setting
quick level change > 1 m/min.
Note:
Since with the function "Quick level change > 1 m/min." the generation
of an average value of the signal processing is considerably reduced,
false reflections by agitators or vessel installations can cause
measured value fluctuations. A false echo memory is thus recom-
mended.
This function enables reading out parameter adjustment data as well
as writing parameter adjustment data into the sensor via the indicating
and adjustment module. A description of the function is available in the
operating instructions manual "Indicating and adjustment module".
The following data are read out or written with this function:
l
Measured value presentation
l
Adjustment
l
Medium
l
Inner diameter of the standpipe (with standpipe versions)
l
Vessel form
l
Damping
l
Linearisation curve
l
Sensor-TAG
l
Displayed value
l
Display unit
Extended setting/Quick
level change
Copy sensor data
42
VEGAPULS 68 • 4 … 20 mA/HART two-wire
6 Set up with the indicating and adjustment module PLICSCOM
29261
-EN
-090305