Operation And Maintenance; Safety Messages; Maintenance - Emerson Rosemount 3144P Reference Manual

Reference Manual
00809-0100-4021
5

Operation and maintenance

5.1

Safety messages

Instructions and procedures in this section may require special precautions to ensure the
safety of the personnel performing the operations. Information that raises potential safety
issues is indicated by a warning symbol ( ). Refer to the following safety messages before
performing an operation preceded by this symbol.
5.2

Maintenance

The transmitter has no moving parts and requires a minimum amount of scheduled
maintenance and features a modular design for easy maintenance. If a malfunction is
suspected, check for an external cause before performing the diagnostics discussed in this
section.
5.2.1 Test terminal (HART
The test terminal, marked as TEST or ("T") on the terminal block, and the negative (–)
terminal accept MINIGRABBER
2-14). The test and the negative terminals are connected across a diode through the loop
signal current. The current measuring equipment shunts the diode when connected
across the test (T) and negative (–) terminals; so as long as the voltage across the
terminals is kept below the diode threshold voltage, no current passes through the diode.
To ensure there is no leakage current through the diode while making a test reading, or
while an indicating meter is connected, the resistance of the test connection or meter
should not exceed 10 ohms. A resistance value of 30 ohms will cause an error of
approximately 1.0 percent of reading.
5.2.2 Sensor checkout
If the sensor is installed in a high-voltage environment and a fault condition or installation
error occurs, the sensor leads and transmitter terminals could carry lethal voltages. Use
extreme caution when making contact with the leads and terminals.
To determine whether the sensor is at fault, replace it with another sensor or connect a
test sensor locally at the transmitter to test remote sensor wiring. Transmitters with
option code C7 (trim to special sensor), are matched to a specific sensor. Select a
standard, off-the-shelf sensor for use with the transmitter, or consult the factory for a
replacement special sensor/transmitter combination.
5.2.3 Electronics housing
The transmitter is designed with a dual-compartment housing. One compartment
contains the electronics module, and the other contains all wiring terminals and
communication receptacles.
Reference Manual
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/4–20 mA only)
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, or alligator clips, facilitate in-process checks (see
Operation and maintenance
December 2019
Figure
193