Reference Manual
00809-0100-4021, Rev FB
August 2011
Rosemount 3144P
5-2
MAINTENANCE
The 3144P 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.
Test Terminal
(HART / 4–20 mA only)
The test terminal, marked as TEST or (“T”) on the terminal block, and the
negative (-) terminal accept MINIGRABBER
™
, or alligator clips, and facilitate
in-process checks (see Figure 2-8 on page 2-11). 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.
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.
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.
Removing the Electronics Module
NOTE
The electronics are sealed in a moisture-resistant plastic enclosure referred to
as the electronics module. This module is a non-repairable unit and the entire
unit must be replaced if a malfunction occurs.
The 3144P electronics module is located in the compartment opposite the
wiring terminals.
Use the following procedure to remove the electronics module:
1. Disconnect the power to the transmitter.
2. Remove the cover from the electronics side of the transmitter housing
(see “Transmitter Exploded View” on page A-11). Do not remove the
covers in explosive atmospheres with a live circuit. Remove the LCD
display, if applicable.
Aotewell Ltd
www.aotewell.com
Industry Automation
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