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11 Applications and functions
VEGAMET 861 • 4 … 20 mA/HART
58866-EN-200401
11 Applications and functions
The controller contains already preset applications and functions,
which can be easily adjusted by means of an application assistant via
PACTware/DTM or the VEGA Tools app. The following applications/
functions are described here as examples.
•
Level measurement in storage tanks with overfill protection/dry run
protection
•
Pump station with pump control function
•
Flow measurement flume/weir
11.1 Level measurement in storage tanks with
overfill protection/dry run protection
The level is detected by a sensor and transmitted to the controller
by means of a 4 … 20 mA signal. Here, an adjustment is carried out,
converting the input value delivered by the sensor into a percentage
value.
Depending on the geometrical form of the tank, the vessel volume
does not increase linearly with the level, e.g. with an horizontal cylin-
drical tank. This can be compensated by selecting the linearisation
curve integrated in the instrument. This curve states the relationship
between percentage level and vessel volume. If the level is to be
displayed in litres, a scaling must also be carried out. For this pur-
pose, the linearised percentage value is converted into a volume, for
example with the unit litre.
Filling and emptying are controlled via relay 1 and 2 which are inte-
grated in the controller. During filling, relay mode "
Overfill protection
"
is set. The relay is thus switched off (safe currentless state) when the
max. level is exceeded, and switched on again when the min. level is
underrun (switch-on point < switch-off point). During emptying, mode
"
Dry run protection
" is used. This relay is thus switched off when the
min. level is underrun (safe currentless condition), and switched on
again when the max. level is exceeded (switch-on point > switch-off
point).
Application
