Functional Safety; Range Of Applications For Functional Safety; Safety Function - Siemens SIPART PS2 Operating Instructions Manual

Functional safety

8.1

Range of applications for functional safety

The positioner is suitable for use on valves that satisfy the special requirements in terms of
functional safety up to SIL 2 in accordance with IEC 61508 or IEC 61511. The 6DR5.1.-0....-....-
Z C20 versions are available for this.
These are single-acting positioners for mounting on pneumatic actuators with spring return.
The positioner automatically depressurizes the valve actuator on demand or in case of faults,
which thus switches the valve to the specified safety position.
This positioner meets the following requirement:
● Functional safety up to SIL 2 in accordance with IEC 61508 or IEC 61511 for safe venting
See also
Functional safety in process instrumentation (http://www.siemens.com/SIL)
8.2

Safety function

Safety function on positioner
Depressurizing of the connected actuator is the safety function for the positioner. The built-in
spring brings the valve to the required safety position. Depending on the direction of action of
this spring, the valve is completely opened or closed.
This safety function can be triggered by:
● The signal at the input for the safety shutdown (terminals 81 and 82) is < 4.5 V.
● Failure of the auxiliary power supply via the bus connection.
The safety function is not affected by other device functions, particularly the microcontroller,
software and communication interface. With respect to this safety function, the positioner must
therefore be considered as a type A subsystem in accordance with EN 61508-2.
SIPART PS2 with PROFIBUS PA
Operating Instructions, 02/2016, A5E00127926-AB
This function is also referred to as "safety shutdown" in the device documentation.
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