Section 2
Page 2 - 8
MODEL 346 INSTALLATION AND OPERATION MANUAL
HA243821
Issue 5 Mar 98
2.3.2 SIGNAL WIRING (Cont.)
CURRENT INPUTS (RECORDER SUPPLY)
The 24 V dc to operate a transducer can be provided by a recorder-mounted supply which is connected at the
terminal board to the shunt (normally 250
Ω
, converting the 4 to 20 mA signal to 1 to 5 V) (see figure 2.3.2d).
Figure 2.3.2d Current input connections (recorder supply)
CURRENT INPUTS (EXTERNAL SUPPLY)
The connection of a 4 to 20 mA device with a separate, external power supply requires only the use of a shunt
resistor to convert the current signal into a voltage input (1 to 5 V with a 250
Ω
shunt).
Figure 2.3.2e Current input connections (external supply)
Transmitter
Transmitter
power supply
+
–
–
+
Current loop
external wiring
Shunt
Recorder
+
–
Black
Black
Black
Red
Red
Red
+
Transmitter
+
-
Other transmitters
+
Channel input
+
+
Only one channel
shown, for clarity.
Long terminal cover
Recorder rear
terminal panel
User terminal block
Shunt
Transmitter Power Supply
PCB
-
