7 Connection
FLUXUS F60*
7.1 FLUXUS *601
55
UMFLUXUS_F60xV5-0EN, 2017-10-16
If the polarity of the current source is inversed, only the sign of the measured current will
change.
An external voltage source U
ext
is necessary. It has to provide a current of min. 20 mA
and
• supply sufficient power for the requirements of the passive current source and
• cover the voltage drop at the input resistor (1 V at 20 mA) and
• cover all other voltage drops (e.g., cable resistance) in the circuit.
If the transmitter has an active output, the output can be used as power supply by means
of an adapter, see section 7.1.4.4.
Tab. 7.3:
Connection of a passive current source
input
transmitter
external circuit
remark
internal circuit
connection
passive
current input
short circuit current:
max. 40 mA
Example
A passive current source with an external power supply (e.g., a pressure sensor) is to
be connected to a passive current input.
Technical data of the pressure sensor:
U
S
= 11...30 V DC
I
a
= 4...20 mA (I
a max
= 22 mA)
U
ext
required for the operation of the passive pressure sensor is:
U
ext min
= U
S min
+ I
a max
· R
i
+ I
a max
· R
c
U
ext min
= 11 V + 22 mA · 50
Ω
+ 22 mA · 2
Ω
U
ext min
= 12.14 V
U
ext max
= U
S max
U
ext max
= 30 V
U
s
– operating voltage of the pressure sensor
I
a
– output current
R
i
– input resistance
R
c
– cable resistance
+
-
+
-
-
+