Safety Manual
Operating Instructions, 06/2012, A5E03433511-05
9
General description of functional safety
2
2.1 Safety-instrumented system
This chapter describes the functional safety in general and not specific to a device. The
devices in the examples are selected as representative examples.
System description
The sensor (analyzer), logic unit/control system and final controlling element combine to
form a safety-instrumented system, which executes a safety function.
Transmitter
(Analyzer, sensor)
Automation system
Measured value
Final controlling element
Shutdown signal
Figure 2-1 Safety-related system
Functional principle
The transmitter generates a process-related measured value that is transferred to the
automation system. The automation system monitors this measured value. If the measured
value exceeds the range of the high or low limit, the automation system generates a
shutdown signal for the connected final controlling element, which switches the associated
valve to the specified safety position.
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