42
6 Set up with the display and adjustment module
WIKA Operating Instructions - Process pressure transmitter CPT-2x
4. Enter the value for the full vessel (e.g. 10 m) corresponding to the
percentage value.
5. Save settings with
[OK]
The max. adjustment is finished.
For an adjustment with filling, simply enter the actual measured value
indicated at the bottom of the display.
A linearization is necessary for all applications in which the measured
process variable does not increase linearly with the measured value.
This applies for example to the flow measured via the differential
pressure or the vessel volume measured via the level. Correspond-
ing linearization curves are preprogrammed for such cases. They
represent the correlation between the measured value percentage
and process variable. The linearization applies to the measured value
indication and the current output.
With flow measurement and selection "
Linear
" display and output
(percentage/current) are linear to "
Differential pressure
". This can
be used, for example, to feed a flow computer.
With flow measurement and selection "
Extraction by root
"display and
output (percentage/current) are linear to "Flow".
4)
With flow in two directions (bidirectional) a negative differential pres-
sure is also possible. This must already be taken into account in menu
item "
Min. adjustment flow
".
Caution:
Note the following, if the respective sensor is used as part of an over-
fill protection system according to WHG:
If a linearisation curve is selected, the measuring signal is no longer
necessarily linear to the filling height. This must be considered by the
user especially when setting the switching point on the limit signal
transmitter.
Since the parameter adjustment of the Function Block 1 (FB1) is very
comprehensive, it was divided into various submenu items.
In menu item "
Channel
" you determine the input signal for further
processing in AI FB 1.
As input signals, the output values of Transducer Block (TB) can be
selected.
Linearisation
AI FB1
AI FB1 - Channel
4)
The device assumes an approximately constant temperature and static
pressure and calculates the flow rate from the measured differential pressure
using the characteristic curve extracted by root.