Functional safety for SIPART PS2 FF
20
A5E00489774-02, 10/2013
1.2
Scope of this document
This document deals with the SIPART PS2 FF positioner exclusively as part of a safety function.
This document only applies in conjunction with the following
No.
Name
Order no.
/1/
SIPART PS2 FF Device Manual 6DR56..
A5E00214569
1.3
Notes on warranty
The contents of this manual shall not become part of or modify any prior or existing agreement, commitment or legal
relationship. The sales contract contains all obligations on the part of Siemens as well as the complete and solely applicable
warranty conditions. Any statements regarding device versions described in the manual do not create new warranties or
modify the existing warranty.
The content reflects the technical status at the time of publishing. Siemens reserves the right to make technical changes in
the course of further development.
2
Functional safety
2.1
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
)
2.2
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.
This function is also referred to as "safety shutdown" in the device documentation.
●
Failure of the auxiliary power supply via the bus connection.
The safety function is not effected 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.
Situations in which it is not possible to depressurize the actuator on demand or in the case of a fault represent a dangerous
failure.
