ABB RET 54 Series Technical Reference Manual, General page 58

RET 54_
58
Transformer Terminal
Technical Reference Manual, General
Resistance sensors
The resistance sensors may be connected to the RTD/analog input according to
either the three-wire or the two-wire connection principle. With the three-wire
measuring principle, the wire resistance is automatically compensated. The resistor,
or RTD sensor, is connected across the IN+ and IN- inputs, and the - side of the
resistor/RTD sensor is connected to the GND input. The leads connected to the IN+
and GND inputs must be of the same type.
Resistor sensor
Fig. 5.1.9.6.-4 Principle diagram of the three-wire connection
With the two-wire connection principle, the IN- and GND terminals are linked
together. The resistor is connected across the IN+ and IN- inputs.
Resistor sensor
Fig. 5.1.9.6.-5 Principle diagram of the two-wire connection
SHUNT
IN +
IN -
GND
SHUNT
IN +
IN -
GND
1MRS755225
G
mA
+
-
DIFF
resist3w_b
G
mA
+
-
DIFF
resist2w_b