VEGA Capacitive electrodes EK Profibus PA - Manual (Page 31)

Capacitive electrodes EK - Profibus PA 31
Arrow keys (5)
With the keys > and <, you can move within
the menu level from one menu item to the
other.
Digital indication (1)
On the digital indication, the actual measured
value is displayed during operation. When
you adjust the instrument, the clear text
indication displays the appropriate function.
Branching point from which you can
change to a lower menu.
This symbol informs you about an ensuing
safety enquiry.
Adjustment steps
On the following pages, you will find the menu
schematic of the adjustment module
MINICOM.
Set up the sensor in the following sequence.
The numbers correspond to the setup
sequence. You will find the numbers near the
appropriate menu items in the menu
schematic on the following pages.
1. Sensor optimisation
2. Adjustment
3. Conditioning
4. Outputs
1. Sensor optimisation
With this function, you can set the sensor
optimisation suitable for your application. With
it, the phase angle of the phase selective
admittance processing (PSA) is modified.
"Mode 1" is preset.
Setup
Mode 1 = Standard (90°)
The standard setting is recommended for
unproblematic applications such as e.g.
liquids with small DK values or with
electrodes in conjunction with a concentric
tube.
The standard setting is also recommended
for non-conductive vessels with an exterior
grounding surface.
Mode 1 is a pure capacitance measurement,
the ohmic conductance is not taken into
account in the measuring result.
Application:
- standard setting
- non-conductive liquids up to approx. 50 µS
- compensation of conductance changes in
liquids
- generally with partly insulated electrodes in
liquids
- non-conductive solids without moisture
content
- with insufficient product grounding
- with electrodes in conjunction with a
concentric tube
- in non-conductive vessels with exterior
grounding surface.
Mode 2 = PSA (45°)
For buildup, varying product moisture
content.
With this mode, the patented phase selective
admittance processing (PSA) is set. This
setting is recommended for problematic
applications in solids, mainly if fluctuations of
the moisture content occur, and in conductive
liquids that stick to the electrode.
The capacitance and the ohmic conductance
are measured separately, the capacitance
value is corrected by calculating it with the
ohmic conductance, so that the measurement
errors caused by conductive buildup or
varying product moisture content are
compensated.
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