Vega MINITRAC 31 Operating Instructions Manual page 33

Application
Background radiation
Units
Adjustment
Linearisation
MINITRAC 31 • Foundation Fieldbus
Enter here, the respective application.
This menu item enables adaptation of the sensor to the requested ap-
plication. You can choose between the following applications: " Level",
" Density", " Limit level", " X-ray alarm" or " Real value correction".
The natural radiation on earth influences the accuracy of the meas-
urement.
With this menu item the natural background radiation can be faded
out.
For this purpose, the MINITRAC 31 measures the natural background
radiation and sets the pulse rate to zero.
In the future, the pulse rate from this background radiation will be
automatically deducted from the total pulse rate. This means: only
the component of the pulse rate originating from the source will be
displayed.
The source container must be closed for this setting.
In this menu item you can select the units of the process value and
the temperature.
In this menu item you can enter the measuring range (min. and max.
process value) of the sensor.
These settings influence the signal output of the sensor.
Enter in the menu window " Max. process value" the max. level (full),
e.g. in " m".
Enter in the menu window " Min. process value" the min. level
(empty), e.g. in " m".
In this menu item you can carry out the adjustment of the sensor.
Due to the measuring principle itself, there is no linear relationship
between pulse rate and level. Hence, this adjustment (i.e. linearisa-
tion) must in any case be carried out.
Note:
If you cannot fill the vessel with the original medium, it is also possible
to carry out the adjustment with water.
Prerequisites:
Radiation is switched on - Source container is set to "ON"
The vessel is either completely filled (100 %) or completely emptied
(0 %).
Depending on whether the vessel is full or empty, you can first carry
out the full or the empty adjustment. The MINITRAC 31 sorts the
points automatically according to their level.
Select " Show table" to display and edit the linearisation points.
Select " Linearisation - New" to enter the first point.
Select " Determine count rate" to enter the first point.
The determination of the actual count rate lasts 2 minutes. After the
count rate has been determined, you can accept the value (ct/s).
6 Set up with the display and adjustment module
33