9
5 Connecting to power supply
NCR-21 4 … 20 mA
54408-01-190131
4.3 Mounting instructions
Polarisation
The emitted radar impulses of the radar sensor
are electromagnetic waves. The polarisation is
the direction of the electrical wave component.
By turning the instrument in the mounting strap,
the polarisation can be used to reduce the
effects of false echoes.
The position of the polarisation is in the middle
of the type label on the instrument.
1
Abb. 24: Position of the polarisation
1 Middle of the type label
Inflowing medium
Do not mount the instrument in or above the
filling stream. Make sure that you detect the
product surface, not the inflowing product.
Abb. 25: Mounting of the radar sensor with inflowing
medium
5 Connecting to power
supply
5.1 Preparing the connection
Safety instructions
Always keep in mind the following safety
instructions:
•
Carry out electrical connection by trained,
qualified personnel authorised by the plant
operator
•
If overvoltage surges are expected, overvol-
tage arresters should be installed
Warning:
Connect only in the complete absence
of line voltage.
Voltage supply
Power supply and current signal are carried on
the same two-wire cable. The operating voltage
can differ depending on the instrument version.
The data for power supply are specified in chap-
ter "
Technical data
".
Provide a reliable separation between the
supply circuit and the mains circuits according
to DIN EN 61140 VDE 0140-1.
Power the instrument via an energy-limited cir-
cuit acc. to IEC 61010-1, e.g. via Class 2 power
supply unit.
Keep in mind the following additional factors
that influence the operating voltage:
•
Lower output voltage of the power supply
unit under nominal load (e.g. with a sensor
current of 20.5 mA or 22 mA in case of fault)
•
Influence of additional instruments in the
circuit (see load values in chapter "
Technical
data
")
Connection cable
The instrument is connected with standard
two-wire cable without screen. If electromagne-
tic interference is expected which is above the
test values of EN 61326-1 for industrial areas,
screened cable should be used.
Make sure that the cable used has the required
temperature resistance for the max. occurring
ambient temperature
5.2 Wiring plan
Wire assignment, connection cable
1
2
Abb. 26: Wire assignment in permanently connected
connection cable
1 Brown (+) and blue (-) to power supply or to the
processing system
2 Shielding
925-0374
