VEGA VEGASON 51V…53V - Manual (Page 12)

12 VEGASON 51 V … 53 V
2.2 Configuration of measuring sys-
tems
A measuring system consists of a sensor
and a processing unit. The processing unit
(signal conditioning instrument VEGAMET or
processing system VEGALOG) processes
the level proportional digital meas. signals
and evaluates these in a number of process-
ing routines.
The levels can then be provided as current,
voltage or switching signals and further proc-
essed, e.g. in a weir control.
On the following pages you see the different
instrument configurations called measuring
systems which are shown in the following
partly with a signal processing.
Types and versions - Configuration of measuring systems
Meas. systems in two-wire technology:
• 2 sensors on one two-wire line
(page 13)
• 2 sensors in Ex on one two-wire line
(page 14)
• 15 sensors on one two-wire line
(page 15)
• 3 sensors in Ex on one two-wire line
(page 16)
Ex
Series 50 sensors require for operation in Ex-
areas the Ex-separator VEGATRENN 548 V
Ex, providing intrinsically safe Ex-circuits.
Note to page 14 and 16:
2) Sensor lines should be looped in screened cables.
It is suitable to earth the cable screens on both
ends. However it must be noted that no earth
compensation currents flow via the screens.
Earth compensation currents can be avoided with
earthing on both ends by connecting the cable
screen on one earth end (e.g. in the switching
cabinet) via a capacitor (e.g. 1
µ
F, 100 V) to the
earth potential.
Sensor lines leading to the same separator card,
can be looped together in one screened multiple
wire cable.
Sensor lines leading to other separator cards, must
be looped in separate, screened cables.