VEGA VEGAPULS 45 VBUS - Manual (Page 35)

VEGAPULS 42, 44 and 45 – VBUS 35
Electrical connection
4.4 Configuration of measuring
systems
A measuring system consists of one sensor
and one processing unit. The processing unit
(VEGAMET signal conditioning instrument or
VEGALOG processing system) evaluates the
level-proportional, digital measuring signals
in a number of processing routines and out-
puts the levels as individual current, voltage
or switching signals.
Two sensors can be connected via one two-
wire cable to VEGAMET signal conditioning
instrument. Up to 255 sensors can be con-
nected to the VEGALOG 571 processing
system. 15 sensors (loop powered) can be
connected on one two-wire cable.
Beside the output of the level in percent,
cubic meter or other physical units, as cur-
rent, voltage or switching signal (relay or
transistor), the levels can also be processed
by linked processing algorithms. Scaling,
linearisation, calculation of linearisation
curves, differential generation, addition or
tendency processing are an integral part of
the VEGALOG processing systems and
VEGAMET and are easy to implement via the
menu selection.
On the following page you will see the various
instrument configurations (measuring sys-
tems) consisting of sensor(s) and process-
ing unit.
Ex
Series 40 sensors with VBUS signal require
for operation in Ex areas the Ex separator
VEGATRENN 548V Ex, providing intrinsically
safe Ex circuits to the sensors. Up to nine
sensors (in groups of three sensors) can be
connected to the Ex separator VEGATRENN
548V Ex.
Connection cable
Sensor wiring should be looped in screened
cables. Ground the cable screens on the
processing system, or better, on the sensor.
We recommend grounding the cable screens
on both ends. However, make sure that no
earth compensation currents flow via the
screens. When earthing on both ends, it is
possible to connect the cable shield on one
earth side (e.g. in the switching cabinet) via a
capacitor (e.g. 10 nF; 1500 V).