Emerson Rosemount MCL-220 Reference Manual page 82

Troubleshoot
May 2019
Figure 9-2: Three-Wire RTD Configuration
A. Resistance temperature device
B. Resistance temperature device in
C. Resistance temperature device sense
D. Resistance temperature device return
Although only two wires are required to connect the resistance temperature device to the
transmitter, using a third (and sometimes fourth) wire allows the transmitter to correct for
the resistance of the lead wires and for changes in the lead wire resistance with
temperature.
9.8.2 Simulate temperature
To simulate the temperature input, wire a decade box to the transmitter or junction box as
shown in
Figure 9-3: Simulating Resistance Temperature Device Inputs
A. Resistance temperature device return
B. Resistance temperature device sense
C. Resistance temperature device in
D. Resistance temperature device shield
82
Figure 9-3.
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