Emerson Rosemount 648 Reference Manual page 12

Configuration
May 2020
Table 2-1: Examples of Approximate Basic Error
Sensor input
3-wire RTD
2-wire RTD
(1) Independent of lead wire resistance up to 5Ω per lead.
(2) Unbalanced lead wire resistance is the maximum resistance differences between any of two
leads.
Figure 2-1: Sensor Wiring
Figure 2-2: Sensor Connections
1 2 3 4
2-wire
RTD and Ω
Note
Emerson provides 4-wire sensors for all single element RTDs. Use these RTDs in 3-wire
configurations by leaving the unneeded leads disconnected and insulated with electrical
tape.
12
Approximate basic error
Error in reading is equivalent to unbalanced lead wire resistance
Error in reading equivalent total lead wire resistance
Thermocouple/mV
3-Wire RTD and Ω
1 2 3 4
3-wire
RTD and Ω
(continued)
4-Wire RTD and Ω
2-Wire RTD and Ω
1 2 3 4
1 2 3 4
4-wire T/C and mV
RTD and Ω
Reference Manual
00809-0200-4648
(2)
Rosemount 648 Wireless