Emerson Rosemount, Reference Manual

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182
Reference Manual
00809-0100-4021, Rev GC
Section 6: Certified Safety Instrumented System (Safety-Certified)
April 2014
Certified safety instrumented system (safety-certified)
Damping and alarm levels
User-adjustable damping affects the transmitters ability to respond to changes in the applied
process. The
damping value + response time should not exceed the loop requirements.
Notes
1. Transmitter output is not safety-rated during: configuration changes, multidrop, fixed
current mode, simulation mode, active calibrator mode, and loop test. Alternative
means should be used to ensure process safety during transmitter configuration and
maintenance activities. Loop test, simulation, and active calibrator modes are normally
disabled automatically through the user interface. However, cycling power or
performing a Processor Reset is recommended to ensure these functions are disabled.
This action is effective regardless of the Security switch setting.
2. DCS, or safety logic solver, should be configured to match transmitter configuration.
Figure 6-1 identifies the Emerson standard alarm and saturation levels. Alarm and
saturation values are user-configurable.
Setting the alarm values is a two step process:
a. With a field communicator, select the alarm and saturation levels using the following
Device Dashboard Fast Key sequence: 2, 2, 5, 6.
b. Position the alarm switch to the required HI or LO position.
Figure 6-1. Rosemount Standard Alarm Levels
Security switch
Position the security switch to the “ON” position to prevent accidental or deliberate change of
configuration data during normal operation. Be sure to take transmitter out of fixed current
(loop test) and simulation before setting security switch to “ON”. Alternatively, the Processor
Reset function may be used to restore normal operation while security switch is “ON”.
6.12 Operation and maintenance
6.12.1 Proof test
The following proof tests are recommended. In the event that an error is found in the safety
functionality, proof test results and corrective actions taken must be documented at www.rose-
mount.com/safety.
Use "Table 3-1: Fast Key Sequences" to perform Loop Test, Review – Device Variables, and view
Status.
The required proof test intervals depends upon the transmitter configuration and the
temperature sensor(s) in use. Guidance is available in
Table 6-1 on page 6-183 . Refer to the
FMEDA report for further information.
(1) Transmitter Failure, hardware alarm in LO position.
(2) Transmitter Failure, hardware alarm in HI position.
Normal operation
4 mA
20 mA
20.5 mA
high saturation
21.75
(2)
3.9 mA
low saturation
3.75 mA
(1)