Rtd Or Ohm Inputs; Thermocouple Or Millivolt Inputs - Emerson Rosemount 3144P Reference Manual

Model 3144P
Figure 2-12. Sensor Wiring
Diagram.
2-wire RTD
and Ohms
***
**
Average. Temp./DT/Hot
Backup/Dual-sensor with
2 RTDs
* Transmitter must be configured for a 3-wire RTD in order to recognize an RTD with a compensation loop.
** Rosemount provides 4-wire sensors for all single-element RTDs. You can use these RTDs in 3-wire configurations by leaving the unneeded leads
disconnected and insulated with electrical tape.
*** Typical wiring configuration of a Rosemount dual-element RTD is shown (R=Red, W=White, G=Green, B=Black)
2-16

RTD or Ohm Inputs

If the transmitter is mounted remotely from a 3- or 4-wire RTD, it will operate
within specifications, without recalibration, for lead wire resistances of up to
10 ohms per lead (equivalent to 1,000 feet of 20 AWG wire). In this case, the
leads between the RTD and transmitter should be shielded. If using only two
leads (or a compensation loop lead wire configuration), both RTD leads are in
series with the sensor element, so significant errors can occur if the lead
lengths exceed one foot of 20 AWG wire. For longer runs, attach a third or
fourth lead as described above. To eliminate 2-wire lead resistance error, the
2-wire offset command can be used. This allows the user to input the
measured lead wire resistance, resulting in the transmitter adjusting the
temperature to correct the error.

Thermocouple or Millivolt Inputs

For direct-mount applications, connect the thermocouple directly to the
transmitter. If mounting the transmitter remotely from the sensor, use
appropriate thermocouple extension wire. Make connections for millivolt
inputs with copper wire. Use shielding for long runs of wire.
NOTE
The use of two grounded thermocouples with a dual option Model 3144P
transmitter is not recommended. For applications in which the use of two
thermocouples is desired, connect either two ungrounded thermocouples,
one grounded and one ungrounded thermocouple, or one dual element
thermocouple.
Model 3144P Single Sensor Connections Diagram
3-wire RTD
and Ohms**
Model 3144P Dual-Sensor Connections Diagram
W
W & G
R
G
B
Average.
Temp./DT/Hot
Backup/Dual-sens
or with 2
Thermocouples
4-wire RTD T/Cs and
and Ohms Millivolts
** **
Average. Average.
Temp./DT/Hot Temp./DT/
Backup/Dual Hot Backup/Dual
Sensor with Sensor with
RTDs/ RTDs/
Thermocouples Thermocouples
Reference Manual
00809-0100-4021, Rev AA
RTD with
Compensation Loop*
**
Average. Temp./DT/
Hot Backup/Dual
Sensor with 2 RTDs
with Compensation
Loop
March 2002