VEGA MINITRAC 31 4 … 20 mA_HART - four-wire - Manual (Page 42)

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6 Set up with the display and adjustment module
MINITRAC 31 • 4 … 20 mA/HART - four-wire
40447-EN-131119
In this menu item you can define the characteristics of the sensor and
its behaviour in case of a fault.
In this menu item you can define the behaviour of the current output.
You can specify the current at minimum and maximum density sepa-
rately.
Radiation from external sources can influence the measuring result of
the sensor.
Possible external radiation sources can be, for example, a weld joint
test on a neighbouring facility or other radiation-based instruments.
An X-ray alarm is triggered if the impulses (ct/s) are more than 25 %
above the max. value from the linearization table.
This fault message is only outputted for the period of the increased
X-ray radiation. Then the fault message is automatically reset.
In this menu item you can determine the behaviour of the sensor
when external radiation sources appear.
You can choose whether the sensor should output modulated current
(dithering) or the set fault current in case external radiation appears.
In the case of modulated measuring current (dithering), the last
valid current value is maintained and the current output modulates a
square-wave voltage ±1 mA around this value.
In this menu item you can activate the relay output and determine its
function as well as the switching points.
When the output of the process values is set, you can choose be-
tween overfill and dry run protection.
The relay outputs of the sensor react accordingly.
The following reference values can be selected:
•
None - Relay operates as fail safe relay
•
Electronics temperature
Setup/Current output
mode
Setup/Current output
Min./Max.
Setup/External radiation
alarm
Setup/Relay