8
Reference Manual
00809-0100-4021, Rev JA
Installation
April 2017
Installation
2.2 Installation considerations
2.2.1 General
Electrical temperature sensors, such as resistance temperature detectors (RTDs) and thermocouples
(T/Cs), produce low-level signals proportional to temperature. The Rosemount
™
3144P Temperature
Transmitter converts low-level signals to HART
®
or FOUNDATION
™
Fieldbus and then transmits the signals
to the control system via two power/signal wires.
2.2.2 Electrical
Proper electrical installation is essential to prevent errors due to sensor lead resistance and electrical
noise. For HART communications, the current loop must have between 250 and 1100 ohms resistance.
Refer to Figure 2-13 on page 22 for sensor and current loop connections. F
OUNDATION Fieldbus devices
must have proper termination and power conditioning for reliable operation. Shielded cables must be
used for F
OUNDATION Fieldbus and may only be grounded in one place.
2.2.3 Environmental
Temperature effects
The transmitter will operate within specifications for ambient temperatures between –40 and 185 °F
(–40 and 85 °C). Since heat from the process is transferred from the thermowell to the transmitter
housing, if the expected process temperature is near or beyond specification limits, consider using
additional thermowell lagging, an extension nipple, or a remote mounting configuration to isolate the
transmitter from the process. Figure 2-1 details the relationship between housing temperature rise and
extension length.
Figure 2-1. Transmitter Housing Temperature Rise versus Extension Length for a Test Installation
(1,500 °F)
temperature
Oven
(1,000 °F)
temperature
Oven
(482 °F)
temperature
Oven
Housing Temperature
Rise Above
Ambient °C (°F)
60 (108)
50 (90)
40 (72)
0
30 (54)
20 (36)
10 (18)
3
4
56
789
Extension length (in.)
815 °C
250 °C
540 °C
22
3.6
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