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Reference Manual
00809-0100-4021, Rev FB
August 2011
Rosemount 3144P
7-2
Pr
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s
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SI
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SAFE FAILURE
FRACTION
The Safe Failure Fraction calculation for the combination of the 3144P and
the process sensor must consider the effects of the transmitter’s process
sensor diagnostics. The 3144P FMEDA report should be consulted for
calculated transmitter failure rates. Sensor failure data may be found in
various references, or may be based on the user’s experience history. A copy
of the FMEDA can be found at
http://www.emersonprocess.com/rosemount/safety/safetyCertTemp.htm
INSTALLATION
No special installation practices are necessary with the 3144P in a PU Safety
Instrumented System. However, a full review of the Failure Mode and Security
switches is required. Follow the standard installation requirements (see
Section 2: Installation).
Switches
Failure Mode Switch
The transmitter monitors itself during normal operation using an automatic
diagnostic routine. If the diagnostic routine detects a sensor failure or an
electronics failure, the transmitter goes into high or low alarm, depending on
the position of the failure mode switch.
The analog alarm and saturation values used by the transmitter depends on
whether it is configured to standard (set by the factory) or NAMUR-compliant
operation. These values are also custom-configurable in both the factory and
the field using the Field Communicator. The limits are:
• 21.0
I
23 for high alarm
• 3.5
I
3.75 for low alarm
The values for standard and NAMUR operation are as follows:
Transmitter Security Switch
The transmitter is equipped with a write-protect switch that can be positioned
to prevent accidental and deliberate change of configuration data.
Changing Switch
Position
The Failure Mode and Security switches are located on the top center of the
electronics module (see Figure 7-1 on page 7-3) which is on the electronics
side of the transmitter housing. For transmitters with an LCD display, the
electronics module is located behind the LCD display faceplate.
Without a LCD display
1. If the transmitter is installed, set the loop to manual.
2. Remove the housing cover on the electronics side of the transmitter. Do
not remove the transmitter cover in explosive atmospheres with a live
circuit.
3. Set the switches to the desired position (see Figure 7-1).
4. Replace the transmitter cover. Both covers must be fully engaged to
meet explosion-proof requirements.
5. Set the loop to automatic control.
Characteristics
Standard Operation
NAMUR-Compliant Operation
Fail High
21.75 mA
I
23.0 mA
21.0 mA
I
23.0 mA
High Saturation
I
20.5 mA
I
20.5 mA
Low Saturation
I
3.90 mA
I
3.8 mA
Fail Low
I
3.75 mA
I
3.6 mA
Aotewell Ltd
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Industry Automation
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